Treatment of traveler's diarrhea in subjects having hepatic encephalopathy using rifaximin is disclosed.

Description of the Invention

Hepatic encephalopathy, also known as hepatic coma or portal-systemic encephalopathy (PSE), is a serious, rare, complex, episodic, neuropsychiatric syndrome associated with advanced liver disease. Hepatic encephalopathy is a formidable burden on the patient, his/her family, and the healthcare system; and the current standard of care is inadequate. Overt, episodic HE is common among patients with liver cirrhosis. The condition is rare among individuals in the overall, general population. Overt HE episodes are debilitating, can present without warning, render the patient incapable of self-care, and frequently result in hospitalization. The frequency of hospitalizations due to HE increased since 1993 to over 40,000 patients in 2003; and in 2004, 50,962 patients were hospitalized with a principal diagnosis of HE. HE, as used herein, comprises, for example, episodic, persistent and minimal HE.

The main pathogenesis of HE is related to nitrogenous substances derived from the gut adversely affecting brain function. The most influential of these compounds is thought to be ammonia, a byproduct of protein digestion that is normally detoxified by the liver. Correlation of blood levels with mental state in cirrhosis, however, is inaccurate, in part, because the blood-brain barrier permeability to ammonia is increased in patients with HE. Other gut-derived toxins have also been proposed as being responsible for HE.

In patients with chronic liver disease, the occurrence of hepatic encephalopathy is associated with a low quality of life compared to age-matched patients without HE. Overt HE episodes are debilitating, can present without warning, render the patient incapable of self-care, and frequently result in hospitalization. Patients with HE experience symptoms including fatigue, daytime sleepiness, and lack of awareness (Conn score 1); and confusion and disorientation (Conn score 2) that significantly interfere with day-to-day function and decreased ability for self care. Often, this lack of self care leads to improper nutrition and non-adherence to therapy and further escalates into more severe symptoms such as increased somnolence, gross disorientation and stupor (Conn score 3) or coma (Conn score 4).

A history of overt HE episodes and the severity of HE episodes were also found to be predictive of decreased survival in patients with chronic liver disease. In patients with liver cirrhosis and a history of overt HE episodes, survival probability was 42% at 1 year and 23% at 3 years after experiencing an HE episode. In another analysis, the occurrence of an HE episode of Conn score 2 in patients with cirrhosis was associated with a 4-fold increase in the risk of death.

The inventors of the instant application have determined that there is a correlation between CFF and venous ammonia concentration and the occurrence of breakthrough HE events. Moreover, the inventors have determined that time weighted average CFF or venous ammonia concentration is an accurate predictor of breakthrough HE events and prognosis of subjects with HE. In another embodiment, the inventors have determined that subjects who continue taking Rifaximin for a long duration of time, e.g., greater than 1.5 years, continue to see beneficial results, e.g., decreased incidence of breakthrough HE events.

In certain embodiments, provided herein are methods for determining if a subject has a neurological disease or HE. The methods presented herein rely on determining the critical flicker frequency or the venous ammonia level.

Critical flicker frequency, also called CFF, can be determined, for example, by standard methods known in the art. Moreover, commercial instruments are available to measure CFF, which are known by those skilled in the art.

Critical flicker frequency tests utilize, for example, the correlation between cerebral processing of oscillatory visual stimuli and CNS impairment due to increased HE severity. This test identifies a frequency at which a flickering light is perceived by a subject as a steady light. A decline in this frequency has been associated with increasing severity of HE. In one example, circular light pulses with a 1:1 ratio between the visual impulse and the interval were used with decreasing frequency in gradual steps of 0.5 to 0.1 Hz/second. The frequency of the white light, which is initially generated as a high-frequency pulse (50 Hz) and which gives the patient the impression of a steady light, can be reduced gradually until the subject had the impression that the steady light had changed to a flicker. The subject registered this change by pressing a hand-held switch. The flicker frequencies can be measured multiple times and the mean values for each subject can be calculated.

In some embodiments, CFF values are tracked over time for each subject. From these values the area under the CFF versus time curve (AUC) could be calculated using calculations that are standard in the art. For example, AUC can be calculated using the trapezoidal rule. To use the trapezoidal rule, data points are connected by straight line segments, perpendiculars are erected from the abscissa to each data point, and the sum of the areas of the triangles and trapezoids so constructed is computed and equals the AUC.

To accurately describe the variation in the CFF over time for each subject the time-weighted average (twa) can be computed. To calculated the twa, the results of the CFF test over time or the venous ammonia levels are expressed as (see Original Patent).

The correlation between twa and the presence or absence of breakthrough HE episode can be analyzed with analysis of variance and Spearman rank correlation coefficient. Additionally, a ROC curve analysis can be performed to evaluate the accuracy of the twa to discriminate between the presence or absence of breakthrough episodes. A ROC analysis for the data collected in the Examples demonstrated that the methodology is a highly accurate predictor of HE.

These toxic compounds gain access to the systemic circulation as a result of decreased hepatic function or portal-systemic shunts. Once in brain tissue, the compounds produce alterations of neurotransmission that affect consciousness and behavior. HE is attributed to global central nervous system depression from nitrogenous compounds that result in excitation of gamma-aminobutyric acid (GABA) and decreased neurotransmission of glutamate.

Precipitating factors include azotemia (29%), sedatives, tranquilizers, analgesics (24%), gastrointestinal bleeding (18%), excess dietary protein (9%), metabolic alkalosis (11%), infection (3%), constipation (3%). Surgery, particularly transjugular intrahepatic portal-systemic shunt (TIPS) procedures, also may precipitate HE. HE due to unknown causes accounts for only 2% of cases.

Initial manifestations are subclinical and require psychometric testing for diagnosis. There are 4 progressive stages of impairment known as the West Haven criteria (or Conn score) which range from Stage 0 (Lack of detectable changes in personality) to Stage 4 (Coma, decerebrate posturing, dilated pupils) as discussed in more detail below.

HE is manifested as a continuum of psychomotor dysfunction, impaired memory, increased reaction time, sensory abnormalities, poor concentration and in severe forms, as coma. Changes may be observed in personality, consciousness, behavior and neuromuscular function. Neurologic signs may include hyperreflexia, rigidity, myoclonus and asterixis (coarse "flapping" muscle tremor). Cognitive tasks such as connecting numbers with lines can be abnormal. Fetor hepaticus (sweet breath odor) may be present. Electroencephalogram (EEG) tracings show nonspecific slow, triphasic wave activity mainly over the frontal areas. Prothrombin time may be prolonged and not correctable with Vitamin K. A computed tomography scan of the head may be normal or show general atrophy. Finally, signs of liver disease such as jaundice and ascites may be noted.

Diagnosis of HE is made on the basis of medical history, and physical and mental status examinations with the required clinical elements being knowledge of existent liver disease, precipitating factor(s), and/or prior history of HE. An EEG may show slow-wave activity, even in mild cases. An elevated serum ammonia level is characteristic but not essential, and correlates poorly with the level of encephalopathy

Management of patients with chronic HE includes 1) provision of supportive care, 2) identification and removal of precipitating factors, 3) reduction of nitrogenous load from the gut, and 4) assessment of the need for long term therapy. The nitrogenous load from the gut is typically reduced using non-absorbable disaccharide (lactulose) and/or antibiotics.

Lactulose is considered a first-line treatment in the United States. Lactulose is metabolized by the intestinal bacteria of the colon, which leads to reduced fecal pH, then to a laxative effect, and finally to fecal elimination. The reduced fecal pH ionizes ammonia (NH.sub.3) to the ammonium ion (NH.sub.4.sup.+) which is used by the bacteria for amino acid and protein synthesis. This lowers the serum ammonia levels and improves mental function.

Conventional therapy aims to lower the production and absorption of ammonia. Lactulose is typically used in doses of 30-60 g daily. However, the dose can be titrated up to 20-40 g TID-QID to affect 2-3 semi-formed bowel movements per day. If lactulose cannot be administered orally or per nasogastric tube, for example to patients with stage 3 and 4 HE, it may be given as a 300 cc (200 g) retention enema.

For acute encephalopathy, lactulose can be administered either orally, by mouth or through a nasogastric tube, or via retention enemas. The usual oral dose is 30 g followed by dosing every 1 to 2 hours until evacuation occurs. At that point, dosing is adjusted to attain two or three soft bowel movements daily.

Lactulose for is readily available over-the-counter. A convenient and relatively tasteless formulation, often referred to in the trade as "lactulose powder for oral solution" can be obtained, for example, from Bertek Pharmaceuticals, Sugarland, Tex. as Kristalose.RTM. in 10 and 20 gm packets. The lactulose syrups commonly sold as laxatives include Cephulac.RTM., Chronulac.RTM., Cholac.RTM., and Enulose.RTM.. These syrups can be substituted for lactulose powder by using sufficient syrup to provide the desired dosage of lactulose; typically, the named syrups contain about 10 gm lactulose in 15 ml of syrup.

Broad-spectrum, GI-active antibiotics including neomycin, metronidazole, vancomycin and paromomycin have been used with or without lactulose. Current guidelines recommend neomycin at 1 to 2 g/day by mouth with periodic renal and annual auditory monitoring or metronidazole at 250. Lactulose can induce diarrhea leading to dehydration, a precipitating factor of HE. Additionally, compliance with lactulose is limited by patient dislike of its overly sweet taste. In addition, a dosing schedule that is linked to bowel habits and side effects of flatulence, bloating, diarrhea (which leads to dehydration), and acidosis make lactulose difficult to use long-term.

Antibiotic use in treatment of HE is hampered by toxicity associated with long-term use. Specifically, systemic absorption of neomycin, metronidazole and ampicillin has led to rare cases of nephrotoxicity, ototoxicity, S. enterocolitis, and/or development of resistant bacterial strains. Additionally, neomycin inhibits only aerobic bacteria. Metronidazole is metabolized slowly in patients with hepatic dysfunction, has a potential for alcohol interactions (disulfuram-like effect), and high blood levels may result in seizures.

One gastrointestinal specific antibiotic is rifaximin. Rifaximin is a nonaminoglycoside, semisynthetic antibiotic derived from rifamycin O. It is a non-systemic, non-absorbed, broad-spectrum, oral antibiotic specific for enteric pathogens of the GI tract. Rifaximin was found to be advantageous in treatment of HE relative to previously used antibiotics; e.g., negligible systemic absorption (<0.4%) regardless of food intake or presence of GI disease and exhibits no plasma accumulation with high or repeat doses. The lack of systemic absorption makes rifaximin safe and well tolerated, thus improving patient compliance and reducing side effects associated with currently known treatments.

Rifaximin (INN; see The Merck Index, XIII Ed., 8304) is an antibiotic belonging to the rifamycin class of antibiotics, e.g., a pyrido-imidazo rifamycin. Rifaximin exerts its broad antibacterial activity, for example, in the gastrointestinal tract against localized gastrointestinal bacteria that cause infectious diarrhea, irritable bowel syndrome, small intestinal bacterial overgrowth, Crohn's disease, and/or pancreatic insufficiency. It has been reported that rifaximin is characterized by a negligible systemic absorption, due to its chemical and physical characteristics (Descombe J. J. et al. Pharmacokinetic study of rifaximin after oral administration in healthy volunteers. Int J Clin Pharmacol Res, 14 (2), 51-56, (1994)).

Rifaximin is described in Italian Patent IT 1154655 and EP 0161534. EP patent 0161534 discloses a process for rifaximin production using rifamycin 0 as the starting material (The Merck Index, XIII Ed., 8301). U.S. Pat. No. 7,045,620 B1 discloses polymorphic forms of rifaximin The applications and patents referred to here are incorporated herein by reference in their entirety for all purposes

A rifamycin class antibiotic is, for example, a compound having the structure of Formula I -- see Original Patent.

Rifaximin is a compound having the structure of formula II -- see Original Patent.

In certain embodiments, the antibiotic comprises one or more of a rifamycin, aminoglycoside, amphenicol, ansamycin, .beta.-Lactam, carbapenem, cephalosporin, cephamycin, monobactam, oxacephem, lincosamide, macrolide, polypeptide, tetracycline, or a 2,4-diaminopyrimidine class antibiotic. Exemplary antibiotics of these classes are listed below.

Rifaximin exerts a broad antibacterial activity in the gastrointestinal tract against localized gastrointestinal bacteria that cause infectious diarrhea, including anaerobic strains. It has been reported that rifaximin is characterized by a negligible systemic absorption, due to its chemical and physical characteristics (Descombe J. J. et al. Pharmacokinetic study of rifaximin after oral administration in healthy volunteers. Int J Clin Pharmacol Res, 14 (2), 51-56, (1994)).

Without wishing to be bound by any particular scientific theories, rifaximin acts by binding to the beta-subunit of the bacterial deoxyribonucleic acid-dependent ribonucleic acid (RNA) polymerase, resulting in inhibition of bacterial RNA synthesis. It is active against numerous gram (+) and (-) bacteria, both aerobic and anaerobic. In vitro data indicate rifaximin is active against species of Staphylococcus, Streptococcus, Enterococcus, and Enterobacteriaceae. Bacterial reduction or an increase in antimicrobial resistance in the colonic flora does not frequently occur and does not have a clinical importance. Rifaximin is currently approved in 17 countries outside the US and was licensed by the Food and Drug Administration (FDA) for the US in May 2004.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. In this application, the use of the singular includes the plural unless specifically stated otherwise. In this application, the use of "or" means "and/or" unless stated otherwise. Furthermore, the use of the term "including", as well as other forms, such as "includes" and "included", is not limiting. Also, terms such as "element" or "component" encompass both elements and components comprising one unit and elements and components that comprise more than one subunit unless specifically stated otherwise. Also, the use of the term "portion" can include part of a moiety or the entire moiety.

All documents, or portions of documents, cited in this application, including but not limited to patents, patent applications, articles, books, and treatises, are hereby expressly incorporated by reference in their entirety for any purpose.

One embodiment is a method of treating or preventing hepatic encephalopathy (HE) by administering a therapeutically effective amount of a gastrointestinal (GI) specific antibiotic to a subject. Examples of gastrointestinal antibiotics as used herein include rifamycin class antibiotics, such as rifaximin.

Embodiments presented herein relate to the discovery of the efficacy of gastrointestinal (GI) specific antibiotics for the treatment and prevention of Hepatic Encephalopathy. Embodiments relate to the use of GI specific antibiotics to prevent the onset of HE symptoms and also to lengthen the time to a first breakthrough HE episode. In one embodiment, the time to a first breakthrough HE episode was measured by an increase of the Conn score to Grade .gtoreq.2 (e.g., 0 or 1 to .gtoreq.2) or a Conn and asterixis score increase of one grade each for those subjects that have a baseline Conn Score of 0. In another embodiment, the time to breakthrough HE episode was measured by the time to any increase from baseline in either the Conn score (mental state grade) or asterixis grade, with Kaplan-Meier estimates of cumulative proportions of subjects with any increase at Days 28, 56, 84, 112, 140, and 168.

Another embodiment was a measurement of the time to a first HE-related hospitalization or the time to development of spontaneous bacterial peritonitis (SBP). Another embodiment was a mean change from baseline in blood ammonia concentration over time or a mean change from baseline in critical flicker frequency values over time. An additional embodiment was indicated by a mean daily lactulose consumption over time, shifts from baseline in Conn scores over time; or shifts from baseline in asterixis grades over time. Unless otherwise specified, a shift of a value is the change of that value from a baseline value.

Other measures of efficacy of the treatments described herein included mean change from baseline in Chronic Liver Disease Questionnaire (CLDQ) scores over time; mean change from baseline in Epworth Sleepiness Scale scores over time; and proportion of subjects who have an Epworth Sleepiness Scale score >10. The evaluation of severity of persistent hepatic encephalopathy may also be based, for example, on Conn scores.

In another embodiment, a subject suffering from, susceptible to or in remission from hepatic encephalopathy (HE) can be administered a rifamycin class antibiotic for between about 24 weeks and 24 months. In treating HE, the rifamycin class antibiotic may be administered to the subject for 12 months and longer, for example for a subject's entire life span. In one embodiment, the antibiotic is administered daily until the death of the subject.

One embodiment, relates to a method of decreasing a subject's risk of having a breakthrough event by administering to the subject a GI specific antibiotic. In one embodiment, the for subjects having a last HE episode equal to or greater than 90 days prior to starting on treatment, the risk of failure occurrence was reduced by 58%. In another embodiment, the risk of failure occurrence was reduced by between about 30-70%. In another embodiment, the risk was reduced by about 40% to 70%. One embodiment relates to decreasing the risk for episodes of overt hepatic encephalopathy in patients suffering from HE. In one embodiment, the patients are over 18 years of age.

In one embodiment, for subjects having a last HE episode more than 90 days prior to administration of a GI specific antibiotic, the risk of failure occurrence was decreased by between about 60%. In another embodiment, the risk of failure occurrence was decreased by between about 2%-80%.

In another embodiment, for subjects having two or fewer HE episodes in the six months prior to starting on treatment, the risk of a breakthrough HE episode was decreased by about a 56%. In one embodiment, the risk of a breakthrough HE episode was decreased by between about a 20%-70%.

In another embodiment, for subjects having greater than two HE episodes in the six months prior to starting on treatment, the risk of a breakthrough HE episode was reduced by about 63%. In another embodiment, the risk was reduced by about 30%-80%.

In one embodiment, the therapeutically effective amount of a gastrointestinal (GI) specific antibiotic comprises from between about 1000 mg to about 1200 mg/day.

In one embodiment, the therapeutically effective amount of a GI specific antibiotic comprises from between about 1100 mg to about 1200 mg/day.

According to one embodiment, the therapeutically effective amount of a GI specific antibiotic comprises about 1150 mg/day.

In another embodiment, the therapeutically effective amount is a dosage regimen of one capsule or tablet of the formulation two times each day, wherein each tablet comprises about 550 mg of the GI specific antibiotic, such as rifaximin.

In one embodiment, the therapeutically effective amount is a dosage regimen of two capsules or tablets three times each day, wherein each capsule comprises about 200 mg of the GI specific antibiotic.

In one embodiment, the therapeutically effective amount is a dosage of 275 mg of a GI specific antibiotic administered four times per day. In another embodiment, 275 mg of a GI specific antibiotic is administered as two dosage forms two times per day.

Another embodiment is a method of maintaining remission of HE in a subject by administering a GI specific antibiotic to the subject.

Another embodiment is a method of increasing time to hospitalization for treatment of HE by administering to the subject a GI specific antibiotic. In one embodiment, the administration of a GI specific antibiotic reduces hospitalization frequency by about 48%.

In another embodiment, a GI specific antibiotic reduces hospitalization frequency by from between about 13% to about 69%.

In one embodiment, treatment with the GI specific antibiotic maintains remission of HE in the subject.

In one embodiment, the GI specific antibiotic is administered to the subject for six months, one year, two to three years or daily until the subject's death.

In one embodiment, a Conn score for the subject is improved over baseline following administration of a GI specific antibiotic.

In one embodiment, a quality of life (QoL) measurement is improved from baseline with administration of a GI specific antibiotic over a course of treatment with rifaximin In one embodiment, the improvised quality is an improvement in the AUC or TWA of the Chronic Liver Disease Questionnaire (CLDQ).

In one embodiment, the GI specific antibiotic is administered to the subject with lactulose, prior to treatment with lactulose, or following treatment with lactulose. In one embodiment the subject or a health care worker is advised to administer the GI specific antibiotic with lactulose. In one embodiment the subject or a health care worker is advised by a pharmaceutical label or insert to administer the GI specific antibiotic with lactulose in order to maintain remission of HE, or to decrease the risk for episodes of overt HE. In one embodiment, the subject or health care worker is advised to administer two 550 mg tablets of rifaximin twice daily with lactulose. Lactulose use may be titrated over time so that the subject maintains 2-3 soft stool bowel movements per day. In one embodiment the lactulose is administered in 15 ml dosages, wherein each 15 ml dosage contains 10 mg of lactulose. In a typical titration, the subject may start on one dosage, or a partial dosage, per day and then move up in 15 ml dosages over time until they reach an end point of 2-3 soft stool bowel movements per day.

In one embodiment, subjects in need of treatment for HE and having a Child-Pugh grade of A or B are treated with a GI specific antibiotic. In another embodiment, subjects in need of treatment for HE having a Child-Pugh grade of A or B are treated with a GI specific antibiotic in combination with lactulose. In another embodiment, subjects having a Child-Pugh grade of A or B, or their health care worker, are advised that they should be treated with a GI specific antibiotic. The advice can be oral or written advice, such as on a pharmaceutical label or package insert. In another embodiment, subjects having a Child-Pugh grade of A or B, or their health care worker, are advised that they should be treated with a GI specific antibiotic in combination with lactulose. In one embodiment, a subject in need of treatment for HE and having a Child-Pugh grade of less than C is treated with a GI specific antibiotic. In one embodiment, a subject in need of treatment for HE and having a Child-Pugh grade of less than C is treated with a GI specific antibiotic and lactulose.

In another embodiment, a subject in need of treatment for HE, or their health care worker is advised of the risk for anaphylaxis prior to treatment with a GI specific antibiotic.

In one embodiment, the GI specific antibiotic is administered with one or more of align, alinia, Lactulose, pentasa, cholestyramine, sandostatin, vancomycin, lactose, amitiza, flagyl, zegerid, prevacid, or miralax.

In one embodiment, following treatment with GI specific antibiotic, a Conn score (mental state grade) of a subject decreases.

In one embodiment, following treatment with a GI specific antibiotic, a Conn score increase from baseline is increased.

In one embodiment, following treatment with a GI specific antibiotic, a delay in time to an increase in Conn score is about 54%. For example, the percentage delay in time to increase in Conn score may be between about 30% to about 70%.

In another embodiment, administration of the GI specific antibiotic prevents an increase in Conn score. For example, administration of the GI specific antibiotic increases the time to an increase from baseline in a Conn score.

In one embodiment, administration of the GI specific antibiotic results in an increase of time to an increase from baseline in an asterixis grade.

In another embodiment, administration of the GI specific antibiotic results in a delay in the time to increase in asterixis grade.

In another embodiment, administration of the GI specific antibiotic results in an increase in time to first HE-related hospitalization.

In another embodiment, administration of the GI specific antibiotic results in an increase in the time to development of spontaneous bacterial peritonitis (SBP).

In another embodiment, administration of the GI specific antibiotic results in a decrease in blood ammonia concentration from baseline after administration of rifaximin For example, the decrease in blood ammonia concentration may be from baseline to 170 days of about 6 .mu.g/dL.

In another embodiment, administration of the GI specific antibiotic results in an increase in critical flicker frequency values from baseline after administration of rifaximin.

In another embodiment, administration of the GI specific antibiotic results in a decrease in daily lactulose consumption from baseline over time after administration with rifaximin.

In another embodiment, administration of the GI specific antibiotic results in a decrease in daily lactulose consumption is from between about 7 doses of lactulose to about 2 doses of lactulose.

In another embodiment, administration of the GI specific antibiotic results in a lactulose use that initially increases from baseline. For example, the lactulose use may be from between about 1 and about 30 days.

In another embodiment, administration of the GI specific antibiotic results in a shift in baseline in Conn scores over time after administration of rifaximin For example, the shift in baseline in Conn scores may be from between about 1 to about 2.

In another embodiment, administration of the GI specific antibiotic results in a shift from baseline in asterixis grades over time.

In another embodiment, administration of the GI specific antibiotic results in a change from baseline in Chronic Liver Disease Questionnaire (CLDQ) scores over time.

In another embodiment, administration of the GI specific antibiotic results in a change from baseline in Epworth Sleepiness Scale scores over time after administration of rifaximin.

As is known, the Model for End-Stage Liver Disease (MELD) score can be utilized to predict liver disease severity based on serum creatinine, serum total bilirubin, and the international normalized ratio for prothrombin time INR. The MELD score and has been shown to be useful in predicting mortality in patients with compensated and decompensated cirrhosis. The maximum score given for MELD is 40. All values higher than 40 are given a score of 40.

In another embodiment, subjects having a MELD level of between about 1 to 24 responded to treatment for HE using administration of the GI specific. In another embodiment, subjects having a MELD level less than or equal to 10 responded to treatment with GI specific antibiotics. In another embodiment, subjects having a MELD level between 11 and 18 respond to treatment with GI specific antibiotics. In another embodiment, subjects having a MELD level between 19 and 24 respond to treatment with GI specific antibiotics. In one embodiment, subjects in need of treatment for HE and having a MELD score of 25 or less are treated with a GI specific antibiotic. In another embodiment, subjects in need of treatment for HE having a MELD score of 25 or less are treated with a GI specific antibiotic in combination with lactulose. In another embodiment, subjects having a MELD score of 25 or less are advised that they should be treated with a GI specific antibiotic. The advice can be oral or written advise, such as on a pharmaceutical label or package insert. In another embodiment, subjects having a MELD score of 25 or less are advised that they should be treated with a GI specific antibiotic in combination with lactulose.

One embodiment presented herein is a method of treating or preventing HE by administering 1100 mg of rifaximin per day to a patient for more than 28 days.

Another embodiment is a method of decreasing lactulose use in a subject. This method includes: administering rifaximin to a subject daily that is being treated with lactulose, and tapering lactulose consumption. For example, the lactulose consumption may be reduced by 1, 2, 3, 4, 5, 6 or more unit dose cups of lactulose from a baseline level. Alternatively, the lactulose use may be reduced by 5, 10, 15, 20, 25, 30, 34, 40, 45, 50, 55, 60, 65, or 70 g lactulose from a baseline level. In one embodiment, the baseline use of lactulose is no use.

One embodiment presented herein is a method of maintaining remission of HE in a subject comprising administering 550 mg of rifaximin twice a day (BID) to the subject.

Another embodiment is a method of increasing time to hospitalization for treatment of HE comprising, administering to a subject 550 mg of rifaximin two times per day (BID).

The term "administration" or "administering" includes routes of introducing a GI specific antibiotic to a subject to perform their intended function. Examples of routes of administration that may be used include injection (subcutaneous, intravenous, parenterally, intraperitoneally, intrathecal), oral, inhalation, rectal and transdermal. The pharmaceutical preparations may be given by forms suitable for each administration route. For example, these preparations are administered in tablets or capsule form, by injection, inhalation, eye lotion, eye drops, ointment, suppository, etc. administration by injection, infusion or inhalation; topical by lotion or ointment; and rectal by suppositories. Oral administration is preferred. The injection can be bolus or can be continuous infusion. Depending on the route of administration, a GI specific antibiotic can be coated with or disposed in a selected material to protect it from natural conditions that may detrimentally affect its ability to perform its intended function. A GI specific antibiotic can be administered alone, or in conjunction with either another agent or agents as described above or with a pharmaceutically-acceptable carrier, or both. A GI specific antibiotic can be administered prior to the administration of the other agent, simultaneously with the agent, or after the administration of the agent. Furthermore, a GI specific antibiotic can also be administered in a proform, which is converted into its active metabolite, or more active metabolite in vivo.

Administration "in combination with" one or more further therapeutic agents includes simultaneous (concurrent) and consecutive administration in any order.

As will be readily apparent to one skilled in the art, the useful in vivo dosage to be administered and the particular mode of administration will vary depending upon the age, weight and mammalian species treated, the particular compounds employed, and the specific use for which these compounds are employed. The determination of effective dosage levels, that is the dosage levels necessary to achieve the desired result, can be accomplished by one skilled in the art using routine pharmacological methods. Typically, human clinical applications of products are commenced at lower dosage levels, with dosage level being increased until the desired effect is achieved.

As used herein, an "increase" or "decrease" in a measurement, unless otherwise specified, is typically in comparison to a baseline value. For example, an increase in time to hospitalization for subjects undergoing treatment may be in comparison to a baseline value of time to hospitalization for subjects that are not undergoing such treatment. In some instances an increase or decrease in a measurement can be evaluated based on the context in which the term is used.

"Carriers" as used herein include pharmaceutically acceptable carriers, excipients, or stabilizers which are nontoxic to the cell or mammal being exposed thereto at the dosages and concentrations employed. Often the physiologically acceptable carrier is an aqueous pH buffered solution. Examples of physiologically acceptable carriers include buffers such as phosphate, citrate, and other organic acids; antioxidants including ascorbic acid; low molecular weight (less than about 10 residues) polypeptide; proteins, such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, arginine or lysine; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrins; chelating agents such as EDTA; sugar alcohols such as mannitol or sorbitol; salt-forming counterions such as sodium; and/or nonionic surfactants such as TWEEN, polyethylene glycol (PEG).

The term "effective amount" includes an amount effective, at dosages and for periods of time necessary, to achieve the desired result, e.g., sufficient to treat or prevent HE in a patient or subject. An effective amount of a GI specific antibiotic may vary according to factors such as the disease state, age, and weight of the subject, and the ability of a GI specific antibiotic to elicit a desired response in the subject. Dosage regimens may be adjusted to provide the optimum therapeutic response. An effective amount is also one in which any toxic or detrimental effects (e.g., side effects) of a GI specific antibiotic are outweighed by the therapeutically beneficial effects.

"Ameliorate," "amelioration," "improvement" or the like refers to, for example, a detectable improvement or a detectable change consistent with improvement that occurs in a subject or in at least a minority of subjects, e.g., in at least about 2%, 5%, 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, 100% or in a range between about any two of these values. Such improvement or change may be observed in treated subjects as compared to subjects not treated with rifaximin, where the untreated subjects have, or are subject to developing, the same or similar disease, condition, symptom or the like. Amelioration of a disease, condition, symptom or assay parameter may be determined subjectively or objectively, e.g., self assessment by a subject(s), by a clinician's assessment or by conducting an appropriate assay or measurement, including, e.g., a quality of life assessment such as a Chronic Liver Disease Questionnaire (CLDQ), a slowed progression of a disease(s) or condition(s), a reduced severity of a disease(s) or condition(s), or a suitable assay(s) for the level or activity(ies) of a biomolecule(s), cell(s) or by detection of HE episodes in a subject. Amelioration may be transient, prolonged or permanent or it may be variable at relevant times during or after a GI specific antibiotic is administered to a subject or is used in an assay or other method described herein or a cited reference, e.g., within timeframes described infra, or about 1 hour after the administration or use of a GI specific antibiotic to about 28 days, or 1, 3, 6, 9 months or more after a subject(s) has received such treatment.

The "modulation" of, e.g., a symptom, level or biological activity of a molecule, or the like, refers, for example, that the symptom or activity, or the like is detectably increased or decreased. Such increase or decrease may be observed in treated subjects as compared to subjects not treated with a GI specific antibiotic, where the untreated subjects have, or are subject to developing, the same or similar disease, condition, symptom or the like. Such increases or decreases may be at least about 2%, 5%, 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, 100%, 150%, 200%, 250%, 300%, 400%, 500%, 1000% or more or within any range between any two of these values. Modulation may be determined subjectively or objectively, e.g., by the subject's self assessment, by a clinician's assessment or by conducting an appropriate assay or measurement, including, e.g., quality of life assessments or suitable assays for the level or activity of molecules, cells or cell migration within a subject. Modulation may be transient, prolonged or permanent or it may be variable at relevant times during or after a GI specific antibiotic is administered to a subject or is used in an assay or other method described herein or a cited reference, e.g., within times descried infra, or about 1 hour of the administration or use of a GI specific antibiotic to about 3, 6, 9 months or more after a subject(s) has received a GI specific antibiotic.

The term "modulate" may also refer to increases or decreases in the activity of a cell in response to exposure to a GI specific antibiotic, e.g., the inhibition of proliferation and/or induction of differentiation of at least a sub-population of cells in an animal such that a desired end result is achieved, e.g., a therapeutic result of GI specific antibiotic used for treatment may increase or decrease over the course of a particular treatment.

The term "obtaining" as in "obtaining a GI specific antibiotic" is intended to include purchasing, synthesizing or otherwise acquiring a GI specific antibiotic.

The phrases "parenteral administration" and "administered parenterally" as used herein includes, for example, modes of administration other than enteral and topical administration, usually by injection, and includes, without limitation, intravenous, intramuscular, intraarterial, intrathecal, intracapsular, intraorbital, intracardiac, intradermal, intraperitoneal, transtracheal, subcutaneous, subcuticular, intraarticulare, subcapsular, subarachnoid, intraspinal and intrasternal injection and infusion.

Pharmaceutical Preparations

Embodiments also provide pharmaceutical compositions, comprising an effective amount of a rifaximin described herein and a pharmaceutically acceptable carrier. In a further embodiment, the effective amount is effective to treat a bacterial infection, Crohn's disease, hepatic encephalopathy, antibiotic associated colitis, and/or diverticular disease in a subject further suffering from hepatic insufficiency.

Embodiments also provide pharmaceutical compositions comprising rifaximin and a pharmaceutically acceptable carrier. Doses may be selected, for example on the basis of desired amounts of systemic adsorption, elimination half-life, serum concentration and the like. Embodiments of the pharmaceutical composition further comprise excipients, for example, one or more of a diluting agent, binding agent, lubricating agent, disintegrating agent, coloring agent, flavoring agent or sweetening agent. One composition may be formulated for selected coated and uncoated tablets, hard and soft gelatin capsules, sugar-coated pills, lozenges, wafer sheets, pellets and powders in sealed packet. For example, compositions may be formulated for topical use, for example, ointments, pomades, creams, gels and lotions.

In an embodiment, rifaximin is administered to the subject using a pharmaceutically-acceptable formulation, e.g., a pharmaceutically-acceptable formulation that provides sustained delivery of the rifaximin to a subject for at least 12 hours, 24 hours, 36 hours, 48 hours, one week, two weeks, three weeks, or four weeks after the pharmaceutically-acceptable formulation is administered to the subject.

In certain embodiments, these pharmaceutical compositions are suitable for topical or oral administration to a subject. In other embodiments, as described in detail below, the pharmaceutical compositions presented herein may be specially formulated for administration in solid or liquid form, including those adapted for the following: (1) oral administration, for example, drenches (aqueous or non-aqueous solutions or suspensions), tablets, boluses, powders, granules, pastes; (2) parenteral administration, for example, by subcutaneous, intramuscular or intravenous injection as, for example, a sterile solution or suspension; (3) topical application, for example, as a cream, ointment or spray applied to the skin; (4) intravaginally or intrarectally, for example, as a pessary, cream or foam; or (5) aerosol, for example, as an aqueous aerosol, liposomal preparation or solid particles containing the compound.

The phrase "pharmaceutically acceptable" refers to rifaximin compositions containing rifaximin and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit/risk ratio.

The phrase "pharmaceutically-acceptable carrier" includes pharmaceutically-acceptable material, composition or vehicle, such as a liquid or solid filler, diluent, excipient, solvent or encapsulating material, involved in carrying or transporting the subject chemical from one organ, or portion of the body, to another organ, or portion of the body. Each carrier is preferably "acceptable" in the sense of being compatible with the other ingredients of the formulation and not injurious to the subject. Some examples of materials which can serve as pharmaceutically-acceptable carriers include: (1) sugars, such as lactose, glucose and sucrose; (2) starches, such as corn starch and potato starch; (3) cellulose, and its derivatives, such as sodium carboxymethyl cellulose, ethyl cellulose and cellulose acetate; (4) powdered tragacanth; (5) malt; (6) gelatin; (7) talc; (8) excipients, such as cocoa butter and suppository waxes; (9) oils, such as peanut oil, cottonseed oil, safflower oil, sesame oil, olive oil, corn oil and soybean oil; (10) glycols, such as propylene glycol; (11) polyols, such as glycerin, sorbitol, mannitol and polyethylene glycol; (12) esters, such as ethyl oleate and ethyl laurate; (13) agar; (14) buffering agents, such as magnesium hydroxide and aluminum hydroxide; (15) alginic acid; (16) pyrogen-free water; (17) isotonic saline; (18) Ringer's solution; (19) ethyl alcohol; (20) phosphate buffer solutions; and (21) other non-toxic compatible substances employed in pharmaceutical formulations.

Wetting agents, emulsifiers and lubricants, such as sodium lauryl sulfate and magnesium stearate, as well as coloring agents, release agents, coating agents, sweetening, flavoring and perfuming agents, preservatives and antioxidants can also be present in the compositions.

Examples of pharmaceutically-acceptable antioxidants include: (1) water soluble antioxidants, such as ascorbic acid, cysteine hydrochloride, sodium bisulfate, sodium metabisulfite, sodium sulfite and the like; (2) oil-soluble antioxidants, such as ascorbyl palmitate, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), lecithin, propyl gallate, alpha-tocopherol, and the like; and (3) metal chelating agents, such as citric acid, ethylenediamine tetraacetic acid (EDTA), sorbitol, tartaric acid, phosphoric acid, and the like.

Compositions containing a rifaximin forms disclosed herein include those suitable for oral, nasal, topical (including buccal and sublingual), rectal, vaginal, aerosol and/or parenteral administration. The compositions may conveniently be presented in unit dosage form and may be prepared by any methods well known in the art of pharmacy. The amount of active ingredient which can be combined with a carrier material to produce a single dosage form will vary depending upon the host being treated, the particular mode of administration. The amount of active ingredient which can be combined with a carrier material to produce a single dosage form will generally be that amount of the compound which produces a therapeutic effect. Generally, out of one hundred %, this amount will range from about 1% to about ninety-nine % of active ingredient, preferably from about 5% to about 70%, most preferably from about 10% to about 30%.

Methods of preparing these compositions include the step of bringing into association a rifaximin with the carrier and, optionally, one or more accessory ingredients. In general, the formulations are prepared by uniformly and intimately bringing into association a rifaximin with liquid carriers, or finely divided solid carriers, or both, and then, if necessary, shaping the product.

Compositions suitable for oral administration may be in the form of capsules, cachets, pills, tablets, lozenges (using a flavored basis, usually sucrose and acacia or tragacanth), powders, granules, or as a solution or a suspension in an aqueous or non-aqueous liquid, or as an oil-in-water or water-in-oil liquid emulsion, or as an elixir or syrup, or as pastilles (using an inert base, such as gelatin and glycerin, or sucrose and acacia) and/or as mouth washes and the like, each containing a predetermined amount of a rifaximin as an active ingredient. A compound may also be administered as a bolus, electuary or paste.

The term "pharmaceutical agent composition" (or agent or drug) as used herein refers to a chemical compound, composition, agent or drug capable of inducing a desired therapeutic effect when properly administered to a patient. It does not necessarily require more than one type of ingredient.

The compositions may be in the form of tablets, capsules, powders, granules, lozenges, liquid or gel preparations. Tablets and capsules for oral administration may be in a form suitable for unit dose presentation and may contain excipients. Examples of these are: binding agents such as syrup, acacia, gelatin, sorbitol, tragacanth, and polyvinylpyrrolidone; fillers such as lactose, sugar, maize-starch, calcium phosphate, sorbitol or glycine; tableting lubricants, such as magnesium stearate, silicon dioxide, talc, polyethylene glycol or silica; disintegrants, such as potato starch; or acceptable wetting agents, such as sodium lauryl sulfate. The tablets may be coated according to methods well known in normal pharmaceutical practice. Oral liquid preparations may be in the form of, for example, aqueous or oily suspensions, solutions, emulsions, syrups or elixirs, or may be presented as a dry product for reconstitution with water or other suitable vehicle before use. Such liquid preparations may contain additives such as suspending agents, e.g., sorbitol, syrup, methyl cellulose, glucose syrup, gelatin, hydrogenated edible fats, emulsifying agents, e.g., lecithin, sorbitan monooleate, or acacia; non-aqueous vehicles (including edible oils), e.g., almond oil, fractionated coconut oil, oily esters such as glycerine, propylene glycol, or ethyl alcohol; preservatives such as methyl or propyl p-hydroxybenzoate or sorbic acid, and, if desired, flavoring or coloring agents.

The phrases "systemic administration," "administered systemically," "peripheral administration," and "administered peripherally," as used herein mean the administration of a GI specific antibiotic, drug or other material, such that it enters the subject's system and, thus, is subject to metabolism and other like processes, for example, subcutaneous administration.

The language "therapeutically effective amount" of a GI specific antibiotic refers to an amount of a GI specific antibiotic which is effective, upon single or multiple dose administration to the subject, in inhibiting the bacterial growth and/or invasion, or in decreasing symptoms, such as HE episodes, relating to bacterial growth in a subject. "Therapeutically effective amount" also refers to the amount of a therapy (e.g., a composition comprising a GI specific antibiotic), which is sufficient to reduce the severity of HE in a subject.

As used herein, the terms "prevent," "preventing," and "prevention" refer to the prevention of the recurrence, onset, or development HE episodes or more symptoms of HE. Preventing includes protecting against the occurrence and severity of HE episodes.

As used herein, the term "prophylactically effective amount" refers to the amount of a therapy (e.g., a composition comprising a GI specific antibiotic) which is sufficient to result in the prevention of the development, recurrence, or onset of HE episodes or to enhance or improve the prophylactic effect(s) of another therapy.

"Rifaximin", as used herein, includes solvates and polymorphous forms of the molecule, including, for example, .alpha., .beta., .gamma., .delta., .epsilon., .eta., .zeta. and amorphous forms of rifaximin These forms are described in more detail, for example, in U.S. Ser. No. 11/873,841; U.S. Ser. No. 11/658,702; EP 05 004 635.2, filed 3 May 2005; U.S. Pat. No. 7,045,620; U.S. 61/031,329; and G. C. Viscomi, et al., Cryst Eng Comm, 2008, 10, 1074-1081 (April 2008). Each of these references is hereby incorporated by reference in entirety.

The forms of rifaximin can be advantageously used in the production of medicinal preparations having antibiotic activity, containing rifaximin, for both oral and topical use. The medicinal preparations for oral use may contain one or more forms of rifaximin together with other excipients, for example diluting agents such as mannitol, lactose and sorbitol; binding agents such as starches, gelatines, sugars, cellulose derivatives, natural gums and polyvinylpyrrolidone; lubricating agents such as talc, stearates, hydrogenated vegetable oils, polyethylenglycol and colloidal silicon dioxide; disintegrating agents such as starches, celluloses, alginates, gums and reticulated polymers; coloring, flavoring and sweetening agents.

Medicinal preparations may contain gastrointestinal specific antibiotics together with usual excipients, such as white petrolatum, white wax, lanoline and derivatives thereof, stearylic alcohol, red iron oxide, propylene glycol, talc, sodium lauryl sulfate, ethers of fatty polyoxyethylene alcohols, disodium edentate, glycerol palmitostearate, esters of fatty polyoxyethylene acids, sorbitan monostearate, glyceryl monostearate, propylene glycol monostearate, hypromellose, polyethylene glycols, sodium starch glycolate, methylcellulose, hydroxymethyl propylcellulose, sodium carboxymethylcellulose, microcrystalline cellulose, colloidal aluminium and magnesium silicate, titanium dioxide, propylene glycol, colloidal silicon dioxide, or sodium alginate.

As used herein, "breakthrough HE," includes, for example, an increase of the Conn score to Grade .gtoreq.2 (e.g., 0 or 1 to .gtoreq.2) or a Conn and Asterixis score increase of 1 grade each for those subjects that have a baseline Conn score of 0.

As used herein, "time to the first breakthrough HE episode," includes, for example, the duration between the date of first administration of rifaximin and the date of first breakthrough HE episode.

As used herein, the term "breakthrough HE event", is intended to include a marked, clinically significant deterioration in neurological function caused by toxic substances accumulating in the blood that cause a deleterious effect on self care, and often leads to hospitalization. Breakthrough HE event is also defined as an increase of a Conn Score to .gtoreq.2 (i.e., 0 or 1 to .gtoreq.2) or a Conn score and asterixis grade increase of 1 each for those subjects that have a baseline Conn score of 0.

Provided herein are methods for determining if a subject has a neurological condition by determining the CFF of a subject at two or more time points. In exemplary embodiments, time points can be 1, 2, 3, 4, 5, 6 or 7 days apart; or 2, 3, or 4 weeks apart; or 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 months apart or any time point in between any two values. In other embodiments, a subject may be monitored at routine intervals for life.

The methods presented herein provide that a decrease in CFF between two or more time points is indicative that the probability of an HE breakthrough event is approaching. Moreover, if a subject has a CFF twa value at a time point that is less than 24 Hz, it is indicative that the subject has an increased probability of an HE event. Therefore, a decrease between CFF in two or more time points or a twa of 24 Hz or less is indicative that the subject has HE, has an increased chance of an HE breakthrough event, and/or should be treated with Rifaximin Accordingly, based on the data collected to date, in one embodiment provided herein are methods of determining if a subject has HE, of predicting the occurrence of a breakthrough HE event, or determining the prognosis of a subject by determining a subject's CFF is below 24 Hz, wherein a CFF below 24 Hz is indicative that the subject has HE, is likely to have a breakthrough HE event, or has a poor prognosis. In certain embodiments, a CFF of less than 24 Hz is indicative that a GI specific antibiotic, e.g., rifaximin, should be administered.

Provided herein are prognostic methods based on determining the CFF or twa CFF wherein a twa CFF of less than 24 is indicative of poor prognosis, or wherein a decrease in CFF or twa CFF between measurements at different time points is indicative of poor prognosis. Poor prognosis includes the survival of the subject for less than 2, 3, 4, 5, 6, 7, 8 or more years or as described herein or in the opinion of a healthcare professional, the subject or a person observing the subject.

In other embodiments, provided herein are method for determining if a subject has HE or has an increased risk of having a HE breakthrough event by measuring the venous ammonia level in a subject at two or more time points, wherein an increase in the venous ammonia level is indicative that the subject has HE, has an increased chance of an HE breakthrough event, and/or should be treated with a GI specific antibiotic, e.g., rifaximin In certain embodiments the venous ammonia level is a time weighted average venous ammonia level.

Venous ammonia concentration can be measured using methods that are known to one of skill in the art. The accuracy of ammonia determination is dependent on sample collection. Whole blood is preferred. In one specific method described herein, blood is collect blood from a stasis-free vein into an EDTA evacuated tube. The sample is placed in ice immediately after collecting and mixing. The sample is placed in a cold environment, e.g., on ice, for approximately ten minutes and then centrifuged. The plasma is separated from the sample within fifteen minutes of collection and frozen. Hemolyzed samples should not be used for further analysis.

The frozen sample is subjected to an enzymatic assay to determine the amount of ammonia present in the sample. The sample containing ammonia is mixed with .alpha.-ketoglutarate and reduced nicotinamide adenine dinucleotide phosphate (NADPH) to form L-glutamate and NADP and water. The reaction is catalyzed by glutamate dehydrogenase. The results are determined spectrophotometrically by monitoring the decrease in absorbance at 340 nm due to the oxidation of NADPH. This decrease is proportional to the ammonia concentration.

In other embodiments, provided herein are methods for determining if a subject has a neurological condition by measuring the CFF between two or more time points. A decrease in the CFF between time points is indicative that a subject has a neurological condition. In certain embodiments, the CFF is the twa of CFF events.

According to one embodiment, provided herein are a database having a data structure which contains a number of CFF or venous ammonia levels from subjects. Similarly, at least one of the databases includes a data structure which maintains a number of relationships between the CFF or venous ammonia levels and the disease state of the subjects and that defines the business rules for performing the methods. These business rules can include defined methods for determining if a subject has HE or is at risk of having a breakthrough HE event. Likewise, the business rules can include defined methods for determining if a subject has a neurological condition. The diagnosis or prognosis can be optionally selected using the novel software of the systems and methods presented herein. In this scenario, the systems and methods, including the novel program configurations, will automatically perform the methods presented herein without additional user input.

Provided herein are methods for determining if a subject has a neurological condition by determining the CFF of a subject at two or more time points.

In particular, one such additional method provided herein includes novel software including a number of program modules or components located on a server within the system for creating and populating a database for use in the diagnostic or prognostic methods. In other words, in one embodiment, the systems and methods provide for the creation and management of a particular policy and policy management for a particular client. One of ordinary skill in the art will understand upon reading this disclosure that the various embodiments include novel software including a number of program modules or components located on the computer based system or network, e.g. servers, sending remote clients, and receiving remote clients, for facilitating the methods presented herein.

As used herein, "time to first HE-related hospitalization," includes, for example, the duration between the first dose of rifaximin and the date of first HE-related hospitalization.

As used herein, "time to an increase from baseline in the Conn score" includes, for example, the duration between the first dose of rifaximin and the date of first increase in Conn score.

As used herein, "time to an increase from baseline in the asterixis grade", includes, for example, the duration between the first dose of rifaximin and the date of first increase in asterixis grade.

As used herein, "mean change from baseline in the fatigue domain score of Chronic Liver Disease Questionnaire (CLDQ), at end of treatment (EOT)" is the mean score with a baseline from before the first administration of rifaximin.

As used herein, "mean change from baseline in blood ammonia concentration at EOT," includes the mean score with a baseline from before the first administration of rifaximin.

As used herein, the "time to diagnosis of spontaneous bacterial peritonitis (SBP)," includes, for example, the duration between the first dose of rifaximin and the date of first episode of SBP.

As used herein, the "mean change from baseline at each post-baseline in critical flicker frequency values," is measured, for example, from a baseline established before the first administration of rifaximin.

"GI specific antibiotic," and "GI antibiotic" as used herein include antibiotic known to have an effect on GI disease. For example, a rifamycin class antibiotic (e.g., rifaximin), neomycin, metronidazole, teicoplanin, ciprofloxacin, doxycycline, tetracycline, augmentin, cephalexin, penicillin, ampicillin, kanamycin, rifamycin, vancomycin, rifaximin, and combinations thereof are useful GI specific antibiotics. Even more preferable are GI specific antibiotics with low systemic absorption, for example, rifaximin Low systemic absorption includes, for example, less than 10% absorption, less than 5% absorption, less than 1% absorption and less than 0.5% absorption. Low systemic absorption also includes, for example, from between about 0.01-1% absorption, from between about 0.05-1% absorption, from between about 0.1-1% absorption, from between about 1-10% absorption, or from between about 5-20% absorption.

As used herein, "subject" includes organisms which are capable of suffering from a bowel disorder or other disorder treatable by rifaximin or who could otherwise benefit from the administration of a rifaximin as described herein, such as human and non-human animals. Preferred human animals include human subjects. The term "non-human animals" includes, for example, all vertebrates, e.g., mammals, e.g., rodents, e.g., mice, and non-mammals, such as non-human primates, e.g., sheep, dog, cow, chickens, amphibians, reptiles, etc. Susceptible to a bowel disorder is meant to include subjects at risk of developing a bowel disorder or bowel infection, e.g., subjects suffering from hepatic encephalopothy, hepatic failure or decreased haepatic function, immune suppression, subjects that have been exposed to other subjects with a bacterial infection, physicians, nurses, subjects traveling to remote areas known to harbor bacteria that causes travelers' diarrhea, etc.

A subject "suffering from hepatic insufficiency" as used herein includes subjects diagnosed with a clinical decrease in liver function, for example, due to hepatic encephalopathy, hepatitis, or cirrhosis. Hepatic insufficiency can be quantified using any of a number of scales including a model end stage liver disease (MELD) score, a Child-Pugh score, or a Conn score. A subject's severity of HE may be determined by one or more of a subject's MELD score, a Child-Pugh score, or a Conn score. Said in another way, methods of assessing the amount of or severity of hepatic insufficiency in a subject can include, for example, the use of any of the scoring systems provided above, such as a MELD score, a Child-Pugh score, of a Conn score.

The language "a prophylactically effective amount" of a compound refers to an amount of a compound of formula I, formula II, or otherwise described herein which is effective, upon single or multiple dose administration to the subject, in preventing or treating hepatic encephalopathy.

As used herein, the term "identifying a subject having TD that also has hepatic insufficiency" is intended to mean using clinical data or test results to determine if a subject has TD and hepatic insufficiency. In one embodiment, this identification can be made my a medical professional by using information obtained from the subject, information obtained from the subject's medical records, or information collected from test results. A medical professional having this information available to them and being able to identify subjects having TD and hepatic insufficiency can practice the methods disclosed herein.

As used herein, the term "hepatic insufficiency" includes diseases and disorders in which a subject has defective functional activity of the liver. Clinically, subjects having hepatic insufficiency have decreased, e.g., statistically significantly decreased, liver function. Hepatic insufficiency often leads to liver failure. One exemplary disease which manifests hepatic insufficiency is hepatic encephalopathy.

As used herein, the term "hepatic encephalopathy" refers to a reversible neuropsychiatric abnormality in the setting of chronic or acute liver failure. When a subject has liver impairment, toxic substances that are normally removed by the liver accumulate in the blood, thereby impairing the function of the brain. These toxic substances are often nitrogenous substances, most notably ammonia. Once in brain tissue, the compounds produce alterations of neurotransmission that affect consciousness and behavior. There are 4 progressive stages of impairment associated with HE that are defined by using the West Haven criteria (or Conn score) which range from Stage 0 (lack of detectable changes in personality) to Stage 4 (coma, decerebrate posturing, dilated pupils). Typical symptoms of hepatic encephalopathy can include impaired cognition, a flapping tremor (asterixis), and a decreased level of consciousness including coma (e.g., hepatic coma), cerebral edema, and, possibly, death. Hepatic encephalopathy is commonly called hepatic coma or portal-systemic encephalopathy in the literature.

As used herein, the term "Travelers' diarrhea" refers to gastrointestinal illness common amongst travelers. The majority of cases are caused by bacterial, viral or protozoan infection. The primary source of infection is ingestion of fecally contaminated food or water. The length of treatment for a particular bowel disorder will depend in part on the disorder. For example, HE may be treated every day for the remainder of a subject's life, travelers' diarrhea may only require treatment duration of 12 to about 72 hours, while Crohn's disease may require treatment durations from about 2 days to 3 months. Dosages of rifaximin will also vary depending on the diseases state.

The elimination rate of rifaximin is decreased in a population of subjects with hepatic insufficiency as compared to population of subjects without hepatic insufficiency, systemic exposure to rifaximin is increased in a population of subjects with hepatic insufficiency as compared to population of subjects without hepatic insufficiency, serum level of rifaximin is increased in a population of subjects with hepatic insufficiency as compared to population of subjects without hepatic insufficiency, or clearance rate of rifaximin is decreased in a population of subjects with hepatic insufficiency as compared to population of subjects without hepatic insufficiency.

As used herein, the term "administering rifaximin cautiously" is intended to mean that rifaximin is administered to a subject for the treatment of TD only with consideration of the degree and severity of the subject's hepatic insufficiency. In specific embodiments, the physician or medical professional considers the degree and severity of the subject's hepatic insufficiency, e.g., HE, and may alter the dosage or frequency of the administration, or may decided based on the degree and severity of the subject's hepatic insufficiency, e.g., decide to administer as normal. In other embodiments, the physician or medical professional administers rifaximin and requires additional supervision or medical intervention, i.e., tests to evaluate the level of rifaximin in a subjects blood.

A subject's severity of HE may be determined by one or more of a subject's MELD score, a Child-Pugh score, or a Conn score. Said in another way, methods of assessing the amount of or severity of hepatic insufficiency in a subject can include, for example, the use of any of the scoring systems provided above, such as a MELD score, a Child-Pugh score, of a Conn score.

A Child-Pugh score (sometimes the Child-Turcotte-Pugh score) used to assess the prognosis of chronic liver disease, mainly cirrhosis, is an aggregate score of five clinical measures, billirubin, serum albumin, INR, ascites, and hepatic encephalopathy. Each marker is assigned a value from 1-3, and the total value is used to provide a score categorized as A (5-6 points), B (7-9 points), or C (10-15 points), which can be correlated with one and two year survival rates. Methods for determination and analysis of Child-Pugh scores are well known in the art.

The presence of hepatic insufficiency has been found to have an effect on in vivo bioavailability of rifaximin Thus, making it a criteria for consideration by a healthcare professional (e.g., physician, physician's assistant, nurse practitioner, pharmacist) when prescribing a dose of rifaximin for treatment of a bowel disorder, such as Travelers' diarrhea or IBS. Hepatic insufficiency leads to a clinically statistically significant increase in rifaximin adsorbed by subjects undergoing treatment.

Provided herein are methods of determining a dose of rifaximin for treating, preventing, or alleviating bowel related disorders, particularly Travelers' diarrhea, in a subject further suffering from hepatic insufficiency, e.g. due to hepatic encephalopathy. Bowel related disorders include one or more of hepatic insufficiency, cirrhosis, polycystic liver disease, irritable bowel syndrome, diarrhea, microbe associated diarrhea, Clostridium difficile associated diarrhea, travelers' diarrhea, small intestinal bacterial overgrowth, Crohn's disease, chronic pancreatitis, pancreatic insufficiency, enteritis, colitis, hepatic encephalopathy (or other disease which leads to increases ammonia levels), or pouchitis.

One embodiment is a method of treating Travelers' Diarrhea (TD) in a subject. The method includes: administering rifaximin to a subject suffering from Travelers' Diarrhea; and informing the subject that systemic plasma exposure to rifaximin is increased in subjects suffering from hepatic insufficiency in comparison to subjects not suffering from hepatic insufficiency. In one embodiment, rifaximin is administered cautiously to the subject if they have hepatic insufficiency, e.g., hepatic encephalopathy.

Another embodiment is a method of using rifaximin for treating a patient's condition. The embodiment includes providing a patient with rifaximin and informing the patient or a medical care worker that systemic plasma exposure to rifaximin is increased in patients suffering from hepatic insufficiency, and that administration of rifaximin to a patient with hepatic insufficiency can affect plasma concentration, safety, or efficacy of rifaximin.

Yet another embodiment includes a method of treating a subject suffering from an indication treatable by rifaximin This method includes administering rifaximin to the subject and advising the subject that systemic plasma exposure to rifaximin is increased in subjects suffering from hepatic insufficiency in comparison to subjects not suffering from hepatic insufficiency. In another embodiment, the methods include testing the subject for hepatic insufficiency prior to treatment with rifaximin.

One other embodiment is a method that includes selecting a subject at risk for hepatic insufficiency, and treating the subject with rifaximin, wherein systemic plasma exposure to rifaximin is increased following the treatment in comparison to a subject without hepatic insufficiency.

Another embodiment includes articles of manufacture that comprise, for example, a container holding a pharmaceutical composition suitable for oral administration of rifaximin in combination with printed labeling instructions providing a discussion of when a particular dosage form extends remission of HE or prevents or delays future episodes of HE. The dosage can be modified for administration to a subject suffering from HE, or include labeling for administration to a subject suffering from HE. Exemplary dosage forms and administration protocols are described infra. The composition will be contained in any suitable container capable of holding and dispensing the dosage form and which will not significantly interact with the composition and will further be in physical relation with the appropriate labeling. The labeling instructions may be consistent with the methods of treatment as described hereinbefore. The labeling may be associated with the container by any means that maintain a physical proximity of the two, by way of non-limiting example, they may both be contained in a packaging material such as a box or plastic shrink wrap or may be associated with the instructions being bonded to the container such as with glue that does not obscure the labeling instructions or other bonding or holding means.

In one embodiment, the instructions will inform and/or advise a health care worker, prescribing physician, a pharmacist, or a subject that they should advise a patient suffering from hepatic encephalopathy that administration of rifaximin may induce cytochrome P450. In another embodiment, the instructions will inform the subject and/or the healthcare provider that there is an extended time to remission or relapse of subjects that take rifaximin In another embodiment, the instructions will inform the subject and/or the healthcare worker or provider that rifaximin does not significantly alter the C.sub.max, AUC.sub.0-t, or AUC.sub.0-.infin. of midazolam. In another embodiment, the instructions will inform the subject and/or the healthcare worker or provider that rifaximin does not increase the risk of QT prolongation.

Packaged compositions are also provided, and may comprise a therapeutically effective amount of rifaximin tablets or capsules. Kits are also provided herein, for example, kits for treating HE in a subject. The kits may contain, for example, rifaximin and instructions for use when treating a subject for an HE. The instructions for use may contain prescribing information, dosage information, storage information, and the like.

Kits may include pharmaceutical preparations of the GI specific antibiotics along with pharmaceutically acceptable solutions, carriers and excipients.

Forms of rifaximin can be advantageously used in the production of medicinal preparations having antibiotic activity, containing rifaximin, for both oral and topical use. The medicinal preparations for oral use may contain one or more forms of rifaximin (for example, .alpha. or .beta., .gamma., .delta., .epsilon., .zeta., .eta., .theta., , .kappa., or .lamda.) together with other excipients, for example diluting agents such as mannitol, lactose and sorbitol; binding agents such as starches, gelatines, sugars, cellulose derivatives, natural gums and polyvinylpyrrolidone; lubricating agents such as talc, stearates, hydrogenated vegetable oils, polyethylenglycol and colloidal silicon dioxide; disintegrating agents such as starches, celluloses, alginates, gums and reticulated polymers; coloring, flavoring and sweetening agents.

Solid preparations of gastrointestinal specific antibiotics administrable by the oral route include for instance coated and uncoated tablets, soft and hard gelatin capsules, sugar-coated pills, lozenges, wafer sheets, pellets and powders in sealed packets.

Medicinal preparations may contain gastrointestinal specific antibiotics together with usual excipients, such as white petrolatum, white wax, lanoline and derivatives thereof, stearylic alcohol, red iron oxide, propylene glycol, talc, sodium lauryl sulfate, ethers of fatty polyoxyethylene alcohols, disodium edentate, glycerol palmitostearate, esters of fatty polyoxyethylene acids, sorbitan monostearate, glyceryl monostearate, propylene glycol monostearate, hypromellose, polyethylene glycols, sodium starch glycolate, methylcellulose, hydroxymethyl propylcellulose, sodium carboxymethylcellulose, microcrystalline cellulose, colloidal aluminium and magnesium silicate, titanium dioxide, propylene glycol, colloidal silicon dioxide, or sodium alginate.

West Haven Criteria (Conn Score):

Measurements of change in mental status may be done, for example, by the Conn score (also known as the West Haven score). The Conn score has been widely used as a measure of mental state in HE studies and is based on the criteria of Parsons-Smith as modified by Conn. Asterixis will not be considered when assessing the subject's status using the Conn scoring criteria listed below.

The scale used in the Conn scoring system is provided below. Grade 0=No personality or behavioral abnormality detected Grade 1=Trivial lack of awareness, euphoria or anxiety; shortened attention span; impairment of addition or subtraction Grade 2=Lethargy; disorientation for time; obvious personality change; inappropriate behavior Grade 3=Somnolence to semi-stupor, responsive to stimuli; confused; gross disorientation; bizarre behavior Grade 4=Coma; unable to test mental state

HE is defined as a spectrum of neuropsychiatric abnormalities seen in patients with liver dysfunction, diagnosed after routine exclusion of other known neurologic disease. HE is a major complication of liver cirrhosis, affecting 30-45% patients. In 2006, the CDC listed cirrhosis as the 12th leading cause of death by disease in the U.S. HE affects the patient's consciousness, personality, intellect and neuromuscular function, and may range from a minimal disturbance in cognition, to coma. HE, as used herein, comprises, for example, episodic, persistent and minimal HE.

In the gut, enteric bacteria act on nitrogen-containing substrates to generate ammonia. FIG. 15 (see Original Patent) represents the situation in unaffected HE subjects: ammonia is removed from the blood as it passes through the liver where it is converted to urea, and excreted by the kidneys. In cirrhosis, ammonia from the intestines bypasses the damaged liver as a result of vascular shunts. This increases blood ammonia, which passes into the brain generating glutamine from the amino acid glutamate. The excess glutamine causes many deleterious effects on brain function; it inhibits neurotransmission, interferes with mitochondrial energy metabolism, and causes swelling of astrocytes.

The clinical presentation of HE is classified according to the scheme shown in FIG. 16 (see Original Patent). HE associated with Cirrhosis--the most common by far--is type C. HE Type C is sub-classified into episodic, persistent and minimal categories. Episodic and persistent varieties are clinically readily apparent conditions, and hence are denoted as Overt. Episodic HE presents with impairment in all the neurological functions mentioned above. As the term episodic implies, there are periods between episodes when no distinctive symptoms are seen. Episodes may be precipitated by factors such as constipation, infection, dehydration, GI hemorrhage and certain medications. If the cause is not immediately identified, the episode is referred to as spontaneous.

HE episodes are usually reversible with treatment--but they're often recurring. HE is a clinical diagnosis made by some tools, including the West Haven, or Conn, Score. In use for about 30 years, The HESA scoring algorithm (FIG. 17 (see Original Patent)) is a relatively new tool used for accurate assignment of Conn criteria. Neuromuscular dysfunction can be measured by eliciting asterixis, or flapping tremor. Blood ammonia levels are often measured to support the diagnosis. Neurophysiological tests, such as critical flicker frequency and EEG, are potentially very useful to support the clinical findings. The Conn criteria use an increasing grade to associate with increasing neurological impairment, (ranging from 0=no impairment to 4=coma) Grades 1, 2, and 3 represent an worsening in impairment in: Consciousness--ranging from a trivial lack of awareness to somnolence; impairment in intellectual ability and alterations in personality This assessment can be conducted quickly, requires minimal intervention from the examiner or cooperation from the patient, And we often use information from family or caregivers to help gauge the severity of HE episodes when the patient is confused.

While patients with grade 1 HE can be managed at home by a caregiver, any escalation to grade 2 or higher may require hospitalization and even management in intensive care. The Conn criteria use an increasing grade to associate with increasing neurological impairment, (ranging from 0=no impairment to 4=coma). Grades 1, 2, and 3 represent an worsening in impairment in: consciousness; intellectual ability and alterations in personality. This assessment can be conducted quickly, requires minimal intervention from the examiner or cooperation from the patient, information from family or caregivers is often used to gauge the severity of HE episodes.

While patients with grade 1 HE can be managed at home by a caregiver, any escalation to grade 2 or higher may require hospitalization and even management in intensive care.

There is a similar grading system for asterixis. If an HE patient is asked to hold out their hands just so, a jerky so called asterixis or flapping tremor will be observed. The number of beats is counted and scored from zero for none to four for almost continuous flapping. This is a simple test but requires a cooperative and conscious patient.

HE presents a vicious cycle of dysfunction and disability that has a dramatic effect on patients, their families and the healthcare system. Early on, impairments in behavior, personality, intellect and consciousness affect the patient's social and family life and ability to hold employment. As the condition worsens, it impacts capacity for self care, medication compliance, lack of compliance further intensifies HE symptoms and frequency of episodes. As a result, patients may need in-home assistance and often land in the ER or hospital beds. Severe HE can be a life threatening event, but it more commonly devastates the QOL of patients and their families; some caregivers liken the experience to caring for unpredictably episodic Alzheimer's disease. Impact on caregiver is shown in FIG. 18 (see Original Patent).

In terms of the impact on healthcare, the number of HE discharges more than doubled between 1993 to 2007. See FIG. 19. Costs increased--from about 13 k to 30 k per hospitalization. So, the goals for HE Therapy include, for example, bringing acute episodes to quick resolution, and preventing recurrent episodes. To achieve these goals, we need a safe and effective therapy that is well tolerated for long-term treatment. There are serious limitations to the long-term use of the currently approved therapies. The most common, Lactulose, a non-absorbable disaccharide, targets the gut flora responsible for ammonia production. It exerts its effects mainly by purging, with frequent bowel movements. Lactulose therapy relies on dose self-titration, aim is for 2-3 loose stools a day--unfortunately this goal is often exceeded. At ten unpredictable loose stools per day, leaving home--even for a short walk to the store--may become impossible or embarrassing. Patients go on disability because of Lactulose rather than the HE it was prescribed for. Severe diarrhea can cause dehydration and electrolyte abnormalities that may even precipitate an HE episode. Nausea is not uncommon. Understandably, these factors can lead to poor adherence and limit long term use.

Another approved treatment is neomycin. However, long-term use is severely limited by its damaging side effects which include nephrotoxicity and sensorineural hearing loss--for which patients with advanced liver disease are most susceptible. Not surprisingly, the safety profile of neomycin is not conducive to long-term therapy. Given the limitations with both lactulose and neomycin--there clearly is an unmet medical need for a safe, effective, and well-tolerated long-term therapy. Hepatic encephalopathy is a serious neurological complication of advanced liver disease that disrupts quality of life, ability for self care and compliance, and results in frequent hospitalization

There are limited therapeutic options for HE and there remains an unmet medical need for a safe, effective, and well-tolerated therapy for long-term treatment. There has not been a new treatment for this debilitating disease for 30 years. Physicians have been sufficiently impressed with the efficacy, tolerability and safety data on rifaximin- and their favorable experience with this drug, even prior to the exciting new trial data you will see today--to make rifaximin quite possibly the most widely used antibiotic therapy for HE.

Study 3001 was designed to continuously monitor patients to ensure the validity and completeness of HE breakthrough capture. Following screening, subjects entered a treatment period that included weekly visits and/or phone calls with patients and caregivers. Subjects were followed for the protocol specified 168 days. Complete capture of breakthrough events as well as mortality and provided assurance of the validity of the study outcome. Narratives for each subject experiencing HE breakthrough, AE's resulting in termination, SAEs or death were provided in the NDA. Key entry criteria included: Patients with advanced liver disease, Presenting with at least 2 episodes of HE within 6 months of screening; documented in medical records with a severity equivalent to a Conn score .gtoreq.2; At both screening and baseline, subjects had a Conn score of 0 or 1, a MELD less than or equal to 25 and were required to have a caregiver who assented to the patient's participation; Patients were excluded if they had a condition that could interfere with the protocol assessments, used alcohol within 14 days, sedatives within 7 days or evidence of current drug dependence;

HESA combines both the clinical components of Conn and neuropsychological tests. Administration requires .about.45 minutes. It was used as a tool to establish consistent scoring of Conn across study centers. It provided a continuous reinforcement of standards and definitions

FIG. 17 succinctly covers the clinical assessments and neuropsychological testing of HESA. Rifaximin provided a significant, protective effect as demonstrated by a 58% reduction in the risk of breakthrough HE with a highly significant p-value. The benefit of rifaximin is striking in that 78% of the patients now had zero events over 6 months. This is in contrast to the placebo group where only 54% maintain remission from HE. In a sick population who suffers from frequent adverse events, restricted living and a shortened life span, rifaximin is able to provide a meaningful benefit by preventing deterioration in their mental status and motor skills.

There were a total of 104 events recorded from 299 participating patients. For the components, we are using descriptive statistics using proportion analysis meeting the condition. 86 events, or 83% of the total events, consisted of patients experiencing a Conn Score of >=2, 37% placebo and 20% rifaximin, resulting in a highly significant p-value.

Eighteen (18) events, or 17% of the total events, are included in this next category of patients experiencing a worsening of Conn and asterixis grade of 1 each. 9% of placebo and 2% of rifaximin, also providing a highly significant p-value.

Consistency of effect aids in determining whether the benefit is derived from one or a few subgroups or if the effect is seen generally across all patient subgroups Importantly, we tested for a treatment by subgroup interaction to ascertain homogeneity in response across subgroups. None of the subgroups tested for a significant interaction. Hazard ratios less than 1 indicate that the outcome favors rifaximin and greater than 1 favors placebo. The result seen in all subgroups consistently reflect the clinical benefit in favor of rifaximin This consistency of outcome, coupled with the absence of a subgroup by treatment interaction, support the robustness of the overall treatment effect.

This effect is maintained across subgroups of varying degrees of severity as it relates to MELD and Child-Pugh. Again, there is no subgroup by treatment interaction here and the estimate of the treatment effect is approximately the same across all groups. In total, the subgroup analyses demonstrate the remarkable consistency of the risk reduction seen in the Primary Endpoint analysis across all groups.

The analysis of the time to HE-related hospitalization results in a 50% reduction in risk with a significant p-value. A large proportion of HE episodes resulted either in direct hospitalization or occurred during the hospitalization. It was shown that time to HE-caused hospitalization (defined as time to hospitalization directly resulting from HE), and time to all-cause hospitalization were reduced with rifaximin, and these analyses show 56% and 30% reductions in risk respectively.

Other endpoints included, for example, the time to first worsening in Conn or Asterixis Scores regardless of whether that change led to a breakthrough HE event; patient reported Quality of life, in particular fatigue, using the CLDQ; changes in blood ammonia, believed to be the primary neurotoxin responsible for the HE; and the Critical flicker frequency. The time to first time worsening in Conn Score reflects a 54% reduction in risk. Time to worsening of asterixis or hand flapping, shows a 35% reduction with a trending p-value. These data represent the changes in each domain throughout the course of the trial. The results demonstrate that rifaximin treated patients feel better. The questionnaire uses a 7-point Likert scale with 1=All the time and 7 being none of the time. Thus, greater values represent better quality of life. The change seen here in each subscale suggests a movement on each scale of 1 category improvement over placebo. The changes we see in ammonia and CFF are statistically significant and reflect improvement in favor of rifaximin These results support the treatment effect of rifaximin.

Analyses were undertaken to assess the sensitivity and specificity of breakthrough HE. Patients with lower CFF and fatigue assessments, and a higher blood ammonia concentration had a greater likelihood of experiencing an HE breakthrough. These data provide further evidence that the primary endpoint is objective and clinically meaningful. For 3002, breakthrough HE data were collected to provide supportive information regarding rifaximin's effect of preventing recurrence of HE.

Three populations were treated in study 3002, including, rifaximin-treated patients from Study 3001; crossover placebo-treated patients from Study 3001; and new HE patients.

Rifaximin subjects who maintained remission throughout 3001 demonstrated continued benefit during their participation in 3002. The incidence of breakthrough HE for rifaximin subjects was lower than the 3001 placebo group demonstrating a 90% reduction in the risk of breakthrough HE. Note that approximately 60% of these patients remain free of breakthrough after almost 3 years. 82 placebo treated subjects from the 3001 study were enrolled in 3002 and were followed for breakthrough. Once in the open-label and receiving rifaximin, we see a 79% risk reduction compared to their experience in the 3001 trial.

The all Rifaximin population demonstrates a 2.6-fold increase risk of all-cause mortality for subjects who achieved a Conn score of at least 2.

The following example will discuss new and novel aspects of rifaximin: In vitro and in vivo pharmacological actions of rifaximin that may contribute to its clinical benefit; Rifaximin's ADME properties, including pharmacokinetics and its excretory and metabolic fate; and Drug-drug interaction studies.

Mechanistically, rifaximin binds to the beta-subunit of bacterial DNA dependent RNA polymerase resulting in inhibition of bacterial RNA synthesis. In vivo, rifaximin ameliorates bacterial diarrheal symptoms and the majority of the dose is not absorbed and it concentrates in the gut, with high gut lumen concentrations, approximately 8000 .mu.g/g of stool. Interestingly, treatment of travelers' diarrhea occurs without significant alteration to the overall intestinal pathogen burden.

In vitro, rifaximin has multiple effects at subinhibitory concentrations, including, for example, increasing plasmid cured, reducing plasmid transfer, and reducing virulence.

It was observed that the effects of rifaximin on mammalian cells, including, for example, detoxification pathways such as P-gp and 3A4 may be upregulated in the gut. Rifaximin renders epithelial cells resistant to bacterial colonization and internalization independent of the effects on bacteria and reduces production and absorption of gut-derived neurotoxins, the primary example being ammonia, which lead to HE in liver-impaired patients.

In this example, 50 patients treated with rifaximin 1200 mg/day showed statistically significant blood ammonia reduction. This reduction was accompanied by significant improvement in overall HE grade and individual measures of HE. While discrete blood ammonia concentrations may be variable, serial measurements in individual patients have been associated with HE severity.

Rifaximin is a member of the rifamycin class of antibiotics. The functional group shown in green differentiates rifaximin from other rifamycins and leads to gut-specific activity.

Rifaximin is categorized as BCS 4; poorly soluble and poorly absorbed. It is also a substrate of P-glycoprotein, an efflux transporter. These properties result in very low oral absorption. The small fraction that is absorbed is cleared by three mechanisms: billiary, metabolic and renal. Rifaximin undergoes first pass elimination via biliary excretion as unchanged rifaximin There is one known metabolite; nearly undetectable in healthy subjects, and very low in HE patients, approximately 2.5% of parent exposure. In both healthy and liver disease subjects, rifaximin renal clearance is <0.4%. Orally administered rifaximin is eliminated almost entirely as unchanged rifaximin in the feces. Steady-state rifaximin pharmacokinetics was examined in healthy subjects and in liver impaired subjects. Exposure is quite low in all populations studied.

In healthy volunteers, mean Cmax is less than 4 ng/mL. See FIG. 20. As liver impairment increases, AUC and Cmax increase correspondingly. Even at their highest, exposures remain low, in the ng/mL range. Increased exposure in liver impaired patients is well described in the literature, and may be attributed to several factors, including, for example, protein binding, reduced liver blood flow and reduced metabolic capability. Limited access to the liver due to blood flow shunting around the liver, and reduced metabolism due to impaired hepatocyte enzyme activity, may reduce hepatic clearance. Either or both of the latter two factors may be responsible for reducing clearance of rifaximin and increasing exposure in liver impaired patients.

To put this exposure into further perspective see FIG. 21, which shows rifaximin data in comparison with other antibiotics, on a log scale because of the wide differences.

Patients with greatest liver impairment and highest plasma exposure have rifaximin levels more than 200-fold lower than those achieved with a systemic antibiotic, like rifampin--shown in blue. It's also more than 10-fold lower than exposures observed with oral neomycin--shown here in pink--which is considered to be non-absorbed. Norfloxacin also is used commonly in this population, for SBP prophylaxis; it's a systemic antibiotic with plasma exposures greater than 35-fold higher than rifaximin The potential for rifaximin to cause drug-drug interactions was explored here. Rifaximin does not significantly inhibit any major P450 drug metabolizing enzyme, P-glycoprotein, or BSEP in subjects with normal liver function. Knowing that other members of this class can cause interactions by upregulating important drug metabolizing enzymes, particularly CYP3A4, we examined the potential for this induction in clinical studies. Rifaximin's effect on midazolam, a classic CYP3A4 substrate, was studied in healthy volunteers. After 16 days of rifaximin 550 mg TID, a dose 50% higher than that used for HE, midazolam's AUC was reduced by 10%. See FIG. 22. In contrast, rifampin reduces midazolam AUC by 95% in similar experiments. This difference reflects not only an in vitro potency difference between rifampin and rifaximin, but an in vivo disposition difference between the two compounds in terms of rifaximin's low liver and systemic exposure. Based on these data we do not anticipate clinically significant drug interactions in subjects with normal liver function. In summary, in vitro and in vivo data indicate that rifaximin has bacteriostatic mechanisms as well as the ability to reduce bacterial adhesion and virulence. It lowers ammonia levels (See FIG. 23), which is linked to improvement in HE patients. The essential distinction between rifaximin and other rifamycins is its extremely low solubility and oral absorption, resulting in gut-targeted therapeutic effects and limited systemic exposure. Although liver disease leads to increased systemic exposure of rifaximin, the highest exposures seen with rifaximin are substantially lower than what's observed with other systemic and unabsorbed oral antibiotics. With this low systemic exposure comes a minimized drug-drug interaction risk.

Embodiments presented herein relate to all of the topical preparations, for instance ointments, pomades, creams, gels and lotions.

In solid dosage forms of rifaximin for oral administration (capsules, tablets, pills, dragees, powders, granules and the like), the active ingredient is typically mixed with one or more pharmaceutically-acceptable carriers, such as sodium citrate or dicalcium phosphate, and/or any of the following: (1) fillers or extenders, such as starches, lactose, sucrose, glucose, mannitol, and/or silicic acid; (2) binders, such as, for example, carboxymethylcellulose, alginates, gelatin, polyvinyl pyrrolidone, sucrose and/or acacia; (3) humectants, such as glycerol; (4) disintegrating agents, such as agar-agar, calcium carbonate, potato or tapioca starch, alginic acid, certain silicates, and sodium carbonate; (5) solution retarding agents, such as paraffin; (6) absorption accelerators, such as quaternary ammonium compounds; (7) wetting agents, such as, for example, acetyl alcohol and glycerol monostearate; (8) absorbents, such as kaolin and bentonite clay; (9) lubricants, such as talc, calcium stearate, magnesium stearate, solid polyethylene glycols, sodium lauryl sulfate, and mixtures thereof; and (10) colouring agents. In the case of capsules, tablets and pills, the pharmaceutical compositions may also comprise buffering agents. Solid compositions of a similar type may also be employed as fillers in soft and hard-filled gelatin capsules using such excipients as lactose or milk sugars, as well as high molecular weight polyethylene glycols and the like.

A tablet may be made by compression or molding, optionally with one or more accessory ingredients. Compressed tablets may be prepared using binder (for example, gelatin or hydroxypropylmethyl cellulose), lubricant, inert diluent, preservative, disintegrant (for example, sodium starch glycolate or cross-linked sodium carboxymethyl cellulose), surface-active or dispersing agent. Molded tablets may be made by molding in a suitable machine a mixture of the powdered active ingredient moistened with an inert liquid diluent.

The tablets, and other solid dosage forms of the pharmaceutical compositions described herein, such as dragees, capsules, pills and granules, may optionally be scored or prepared with coatings and shells, such as enteric coatings and other coatings well known in the pharmaceutical-formulating art. They may also be formulated so as to provide slow or controlled release of the active ingredient therein using, for example, hydroxypropylmethyl cellulose in varying proportions to provide the desired release profile, other polymer matrices, liposomes and/or microspheres. They may be sterilized by, for example, filtration through a bacteria-retaining filter, or by incorporating sterilizing agents in the form of sterile solid compositions which can be dissolved in sterile water, or some other sterile injectable medium immediately before use. These compositions may also optionally contain opacifying agents and may be of a composition that they release the active ingredient(s) only, or preferentially, in a certain portion of the gastrointestinal tract, optionally, in a delayed manner. Examples of embedding compositions which can be used include polymeric substances and waxes. The active ingredient can also be in micro-encapsulated form, if appropriate, with one or more of the above-described excipients.

Liquid dosage forms for oral administration of rifaximin include pharmaceutically-acceptable emulsions, microemulsions, solutions, suspensions, syrups and elixirs. In addition to the active ingredient, the liquid dosage forms may contain inert diluents commonly used in the art, such as, for example, water or other solvents, solubilizing agents and emulsifiers, such as ethyl alcohol, isopropyl alcohol, ethyl carbonate, ethyl acetate, benzyl alcohol, benzyl benzoate, propylene glycol, 1,3-butylene glycol, oils (in particular, cottonseed, groundnut, corn, germ, olive, castor and sesame oils), glycerol, tetrahydrofuryl alcohol, polyethylene glycols and fatty acid esters of sorbitan, and mixtures thereof.

In addition to inert diluents, the oral compositions can include adjuvants such as wetting agents, emulsifying and suspending agents, sweetening, flavoring, coloring, perfuming and preservative agents.

Suspensions, in addition to rifaximin may contain suspending agents as, for example, ethoxylated isostearyl alcohols, polyoxyethylene sorbitol and sorbitan esters, microcrystalline cellulose, aluminum metahydroxide, bentonite, agar-agar and tragacanth, and mixtures thereof.

Pharmaceutical compositions for rectal or vaginal administration may be presented as a suppository, which may be prepared by mixing rifaximin with one or more suitable nonirritating excipients or carriers comprising, for example, cocoa butter, polyethylene glycol, a suppository wax or a salicylate, and which is solid at room temperature, but liquid at body temperature and, therefore, will melt in the rectum or vaginal cavity and release the active agent.

Compositions which are suitable for vaginal administration also include pessaries, tampons, creams, gels, pastes, foams or spray formulations containing such carriers as are known in the art to be appropriate.

Dosage forms for the topical or transdermal administration of rifaximin includes powders, sprays, ointments, pastes, creams, lotions, gels, solutions, patches and inhalants. Rifaximin may be mixed under sterile conditions with a pharmaceutically-acceptable carrier, and with any preservatives, buffers, or propellants which may be required.

Ointments, pastes, creams and gels may contain, in addition to rifaximin, excipients, such as animal and vegetable fats, oils, waxes, paraffins, starch, tragacanth, cellulose derivatives, polyethylene glycols, silicones, bentonites, silicic acid, talc and zinc oxide, or mixtures thereof.

Powders and sprays can contain, in addition to rifaximin, excipients such as lactose, talc, silicic acid, aluminium hydroxide, calcium silicates and polyamide powder, or mixtures of these substances. Sprays can additionally contain customary propellants, such as chlorofluorohydrocarbons and volatile unsubstituted hydrocarbons, such as butane and propane.

Rifaximin can be alternatively administered by aerosol. This is accomplished by preparing an aqueous aerosol, liposomal preparation or solid particles containing the compound. A non-aqueous (e.g., fluorocarbon propellant) suspension could be used. Sonic nebulizers are preferred because they minimize exposing the agent to shear, which can result in degradation of the compound.

An aqueous aerosol is made, for example, by formulating an aqueous solution or suspension of the agent together with pharmaceutically-acceptable carriers and stabilizers. The carriers and stabilizers vary with the requirements of the particular compound, but typically include non-ionic surfactants (Tweens.RTM., Pluronics.RTM., or polyethylene glycol), innocuous proteins like serum albumin, sorbitan esters, oleic acid, lecithin, amino acids such as glycine, buffers, salts, sugars or sugar alcohols. Aerosols generally are prepared from isotonic solutions.

Pharmaceutical compositions suitable for parenteral administration may comprise rifaximin in combination with one or more pharmaceutically-acceptable sterile isotonic aqueous or nonaqueous solutions, dispersions, suspensions or emulsions, or sterile powders which may be reconstituted into sterile injectable solutions or dispersions just prior to use, which may contain antioxidants, buffers, bacteriostats, solutes which render the formulation isotonic with the blood of the intended recipient or suspending or thickening agents.

Examples of suitable aqueous and non-aqueous carriers which may be employed in the pharmaceutical compositions include water, ethanol, polyols (such as glycerol, propylene glycol, polyethylene glycol, and the like), and suitable mixtures thereof, vegetable oils, such as olive oil, and injectable organic esters, such as ethyl oleate. Proper fluidity can be maintained, for example, by the use of coating materials, such as lecithin, by the maintenance of the required particle size in the case of dispersions, and by the use of surfactants.

These compositions may also contain adjuvants such as preservatives, wetting agents, emulsifying agents and dispersing agents. Prevention of the action of microorganisms may be ensured by the inclusion of various antibacterial and antifungal agents, for example, paraben, chlorobutanol, phenol sorbic acid, and the like. It may also be desirable to include isotonic agents, such as sugars, sodium chloride, and the like into the compositions. In addition, prolonged absorption of the injectable pharmaceutical form may be brought about by the inclusion of agents which delay absorption such as aluminum monostearate and gelatin.

In some cases, to prolong the effect of a drug, it is desirable to alter the absorption of the drug. This may be accomplished by the use of a liquid suspension of crystalline, salt or amorphous material having poor water solubility. The rate of absorption of the drug may then depend on its rate of dissolution which, in turn, may depend on crystal size and crystalline form. Alternatively, delayed absorption of a drug form is accomplished by dissolving or suspending the drug in an oil vehicle.

Injectable depot forms are made by forming microencapsule matrices of rifaximin in biodegradable polymers such as polylactide-polyglycolide. Depending on the ratio of drug to polymer, and the nature of the particular polymer employed, the rate of drug release can be controlled. Examples of other biodegradable polymers include poly(orthoesters) and poly(anhydrides). Depot injectable formulations are also prepared by entrapping the drug in liposomes or microemulsions which are compatible with body tissue.

When the rifaximin is administered as a pharmaceutical, to humans and animals, it can be given per se or as a pharmaceutical composition containing, for example, 0.1 to 99.5% (more preferably, 0.5 to 90%) of active ingredient in combination with a pharmaceutically-acceptable carrier.

Regardless of the route of administration selected rifaximin which may be used in a pharmaceutical composition presented herein, is formulated into pharmaceutically-acceptable dosage forms by methods known to those of skill in the art.

Actual dosage levels and time course of administration of the active ingredients in the pharmaceutical compositions may be varied so as to obtain an amount of the active ingredient which is effective to achieve the desired therapeutic response for a particular subject, composition, and mode of administration, without being toxic to the subject. An exemplary dose range is from 25 to 3000 mg per day.

XIFAXAN, a tradename for rifaximin, is approved for the following two uses:

1) Traveler's diarrhea: Rifaximin 200 mg are indicated for the treatment of patients (.gtoreq.12 years of age) with travelers' diarrhea caused by noninvasive strains of Escherichia coli. Rifaximin tablets should not be used in patients with diarrhea complicated by fever or blood in the stool or diarrhea due to pathogens other than Escherichia coli.

2) Hepatic encephalopathy: Rifaximin tablets 550 mg are indicated for the maintenance of remission of hepatic encephalopathy in patients .gtoreq.18 years of age.

To reduce the development of drug-resistant bacteria and maintain the effectiveness of rifaximin, and other antibacterial drugs, rifaximin when used to treat infection should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

XIFAXAN, a tradename for rifaximin, is approved for the following two uses:

1) Travelers' Diarrhea

Rifaximin 200 mg is indicated for the treatment of patients (.gtoreq.12 years of age) with travelers' diarrhea caused by noninvasive strains of Escherichia coli.

Rifaximin should not be used in patients with diarrhea complicated by fever or blood in the stool or diarrhea due to pathogens other than Escherichia coli.

2) Hepatic Encephalopathy

Rifaximin 550 mg is indicated for reduction in risk of overt hepatic encephalopathy (HE) recurrence in patients .gtoreq.18 years of age. In the trials of rifaximin for HE, 91% of the patients were using lactulose concomitantly. Differences in the treatment effect of those patients not using lactulose concomitantly could not be assessed.

Rifaximin has not been studied in patients with MELD (Model for End-Stage Liver Disease) scores >25, and only 8.6% of patients in the controlled trial had MELD scores over 19. There is increased systemic exposure in patients with more severe hepatic dysfunction.

Rifaximin can be administered orally with or without food. For treatment of travelers' diarrhea patients should take one 200 mg tablet three times a day for 3 days. For hepatic encephalopathy patients should take one 550 mg tablet two times a day.

Rifaximin tablets are contraindicated in patients with a hypersensitivity to rifaximin, any of the rifamycin antimicrobial agents, or any of the components in rifaximin tablets. Hypersensitivity reactions have included exfoliative dermatitis, angioneurotic edema, and anaphylaxis.

Rifaximin was not found to be effective in patients with diarrhea complicated by fever and/or blood in the stool or diarrhea due to pathogens other than Escherichia coli.

Discontinue rifaximin use if diarrhea symptoms get worse or persist more than 24-48 hours and alternative antibiotic therapy should be considered.

Rifaximin is not effective in cases of travelers' diarrhea due to Campylobacter jejuni. The effectiveness of rifaximin in travelers' diarrhea caused by Shigella spp. and Salmonella spp. has not been proven. Rifaximin should not be used in patients where Campylobacter jejuni, Shigella spp., or Salmonella spp. may be suspected as causative pathogens.

Clostridium difficile-associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including rifaximin, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon which may lead to overgrowth of C. difficile.

C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibiotic use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents.

If CDAD is suspected or confirmed, ongoing antibiotic use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of C. difficile, and surgical evaluation should be instituted as clinically indicated.

Prescribing rifaximin for travelers' diarrhea in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria.

There is increased systemic exposure in patients with severe hepatic impairment. Animal toxicity studies did not achieve systemic exposures that were seen in patients with severe hepatic impairment. The clinical trials were limited to patients with MELD scores <25. Therefore, caution should be exercised when administering rifaximin to patients with severe hepatic impairment (Child-Pugh C).

The safety of rifaximin 200 mg taken three times a day was evaluated in patients with travelers' diarrhea consisting of 320 patients in two placebo-controlled clinical trials with 95% of patients receiving three or four days of treatment with rifaximin The population studied had a mean age of 31.3 (18-79) years of which approximately 3% were .gtoreq.65 years old, 53% were male and 84% were White, 11% were Hispanic.

Discontinuations due to adverse reactions occurred in 0.4% of patients. The adverse reactions leading to discontinuation were taste loss, dysentery, weight decrease, anorexia, nausea and nasal passage irrigation.

All adverse reactions for rifaximin 200 mg three times daily that occurred at a frequency >2% in the two placebo-controlled trials combined are provided in Table 39 (see Original Patent). (These include adverse reactions that may be attributable to the underlying disease.)

The following adverse reactions, presented by body system, have also been reported in <2% of patients taking rifaximin in the two placebo-controlled clinical trials where the 200 mg tablet was taken three times a day for travelers' diarrhea. The following includes adverse reactions regardless of causal relationship to drug exposure -- see Original Patent.

Blood and Lymphatic System Disorders: Lymphocytosis, monocytosis, neutropenia;

Ear and Labyrinth Disorders: Ear pain, motion sickness, tinnitus;

Gastrointestinal Disorders Abdominal distension, diarrhea NOS, dry throat, fecal abnormality NOS, gingival disorder NOS, inguinal hernia NOS, dry lips, stomach discomfort;

General Disorders and Administration Site Conditions: Chest pain, fatigue, malaise, pain NOS, weakness;

Infections and Infestations: Dysentery NOS, respiratory tract infection NOS, upper respiratory tract infection NOS;

Injury and Poisoning: Sunburn;

Investigations: Aspartate aminotransferase increased, blood in stool, blood in urine, weight decreased;

Metabolic and Nutritional Disorders: Anorexia, dehydration;

Musculoskeletal, Connective Tissue, and Bone Disorders: Arthralgia, muscle spasms, myalgia, neck pain;

Nervous System Disorders: Abnormal dreams, dizziness, migraine NOS, syncope, loss of taste;

Psychiatric Disorders: Insomnia;

Renal and Urinary Disorders: Choluria, dysuria, hematuria, polyuria, proteinuria, urinary frequency;

Respiratory, Thoracic, and Mediastinal Disorders: Dyspnea NOS, nasal passage irritation, nasopharyngitis, pharyngitis, pharyngolaryngeal pain, rhinitis NOS, rhinorrhea;

Skin and Subcutaneous Tissue Disorders: Clamminess, rash NOS, sweating increased; and

Vascular Disorders: Hot flashes.

Hepatic Encephalopathy

The data described below reflect exposure to rifaximin 550 mg in 348 patients, including 265 exposed for 6 months and 202 exposed for more than a year (mean exposure was 364 days). The safety of rifaximin 550 mg taken two times a day for reducing the risk of overt hepatic encephalopathy recurrence in adult patients was evaluated in a 6-month placebo-controlled clinical trial (n=140) and in a long term follow-up study (n=280). The population studied had a mean age of 56.26 (range: 21-82) years; approximately 20% of the patients were .gtoreq.65 years old, 61% were male, 86% were White, and 4% were Black. Ninety-one percent of patients in the trial were taking lactulose concomitantly. All adverse reactions that occurred at an incidence .gtoreq.5% and at a higher incidence in rifaximin 550 mg-treated subjects than in the placebo group in thee 6-month trial are provided in Table 40 (see Original Patent). (These include adverse events that may be attributable to the underlying disease.)
 

Claim 1 of 15 Claims

1. A method of treating a subject having Travelers' Diarrhea (TD) comprising: identifying a subject having TD that also has hepatic insufficiency; determining if the subject's Child-Pugh score is Child-Pugh Class C or if the subject's model end stage liver disease (MELD) score is 25 or greater; administering rifaximin cautiously to the subject if his or her Child-Pugh score is Child-Pugh Class C or if his or her MELD score is 25 or greater.

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