The invention relates to a solid oral dosage form comprising a pharmaceutically active ingredient in combination with an enhancer which enhances the bioavailability and/or the absorption of the active ingredient. Accordingly, a solid oral dosage form comprises a drug and an enhancer wherein the enhancer is a medium chain fatty acid ester, ether or salt or a derivative of a medium chain fatty acid, which is, preferably, solid at room temperature and which has a carbon chain length of from 6 to 20 carbon atoms. Preferably, the solid oral dosage form is controlled release dosage form such as a delayed release dosage form.

Description of the Invention

FIELD OF THE INVENTION

The present invention relates to a solid oral dosage form containing enhancers. In particular the invention relates to a solid oral dosage form comprising a pharmaceutically active ingredient in combination with an enhancer which enhances the bioavailability and/or the absorption of the active ingredient and which is a controlled release dosage form such as a delayed release dosage form.

BACKGROUND OF THE INVENTION

The epithelial cells lining the lumenal side of the GIT are a major barrier to drug delivery following oral administration. However, there are four recognised transport pathways which can be exploited to facilitate drug delivery and transport: the transcellular, paracellular, carrier-mediated and transcytotic transport pathways. The ability of a drug, such as a conventional drug, a peptide, a protein, a macromolecule or a nano- or microparticulate system, to "interact" with one or more of these transport pathways may result in increased delivery of that drug from the GIT to the underlying circulation.

Certain drugs utilise transport systems for nutrients which are located in the apical cell membranes (carrier mediated route). Macromolecules may also be transported across the cells in endocytosed vesicles (transcytosis route). However, many drugs are transported across the intestinal epithelium by passive diffusion either through cells (transcellular route) or between cells (paracellular). Most orally administered drugs are absorbed by passive transport. Drugs which are lipophilic permeate the epithelium by the transcellular route whereas drugs that are hydrophilic are restricted to the paracellular route.

Paracellular pathways occupy less than 0.1% of the total surface area of the intestinal epithelium. Further, tight junctions, which form a continuous belt around the apical part of the cells, restrict permeation between the cells by creating a seal between adjacent cells. Thus, oral absorption of hydrophilic drugs such as peptides can be severely restricted. Other barriers to absorption of drugs may include hydrolysing enzymes in the lumen brush border or in the intestinal epithelial cells, the existence of the aqueous boundary layer on the surface of the epithelial membrane which may provide an additional diffusion barrier, the mucus layer associated with the aqueous boundary layer and the acid microclimate which creates a proton gradient across the apical membrane. Absorption, and ultimately bioavailability, of a drug may also be reduced by other processes such as P-glycoprotein regulated transport of the drug back into the gut lumen and cytochrome P450 metabolism.

Therefore, new strategies for delivering drugs across the GIT cell layers are needed, particularly for hydrophilic drugs including peptides, proteins and macromolecular drugs.

Numerous potential absorption enhancers have been identified. For instance, medium chain glycerides have demonstrated the ability to enhance the absorption of hydrophilic drugs across the intestinal mucosa (Pharm. Res. (1994), 11, 1148-54). However, the importance of chain length and/or composition is unclear and therefore their mechanism of action remains largely unknown. Sodium caprate has been reported to enhance intestinal and colonic drug absorption by the paracellular route (Pharm. Res. (1993) 10, 857-864; Pharm. Res. (1988), 5, 341-346). U.S. Pat. No. 4,656,161 (BASF AG) discloses a process for increasing the enteral absorbability of heparin and heparinoids by adding non-ionic surfactants such as those that can be prepared by reacting ethylene oxide with a fatty acid, a fatty alcohol, an alkylphenol or a sorbitan or glycerol fatty acid ester. U.S. Pat. No. 5,229,130 (Cygnus Therapeutics Systems) discloses a composition which increases the permeability of skin to a transdermally administered pharmacologically active agent formulated with one or more vegetable oils as skin permeation enhancers. Dermal penetration is also known to be enhanced by a range of sodium carboxylates [Int. J. of Pharmaceutics (1994), 108, 141-148]. Additionally, the use of essential oils to enhance bioavailability is known (U.S. Pat. No. 5,66,386 AvMax Inc. and others). It is taught that the essential oils act to reduce either, or both, cytochrome P450 metabolism and P-glycoprotein regulated transport of the drug out of the blood stream back into the gut.

Often, however, the enhancement of drug absorption correlates with damage to the intestinal wall. Consequently, limitations to the widespread use of GIT enhancers is frequently determined by their potential toxicities and side effects. Additionally and especially with respect to peptide, protein or macromolecular drugs, the "interaction" of the GIT enhancer with one of the transport pathways should be transient or reversible, such as a transient interaction with or opening of tight junctions so as to enhance transport via the para-cellular route.

As mentioned above, numerous potential enhancers are known. However, this has not led to a corresponding number of products incorporating enhancers. One such product currently approved for use in Sweden and Japan is the Doktacillin.TM. suppository [Lindmark et al. Pharmaceutical Research (1997), 14, 930-935]. The suppository comprises ampicillin and the medium chain fatty acid, sodium caprate (C10).

Provision of a solid oral dosage form which would facilitate the administration of a drug together with an enhancer is desirable. The advantages of solid oral dosage forms over other dosage forms include ease of manufacture, the ability to formulate different controlled release and extended release formulations and ease of administration. Administration of drugs in solution form does not readily facilitate control of the profile of drug concentration in the bloodstream. Solid oral dosage forms, on the other hand, are versatile and may be modified, for example, to maximise the extent and duration of drug release and to release a drug according to a therapeutically desirable release profile. There may also be advantages relating to convenience of administration increasing patient compliance and to cost of manufacture associated with solid oral dosage forms.

SUMMARY OF THE INVENTION

According to the present invention, a solid oral dosage form comprises a drug and an enhancer wherein the enhancer is a medium chain fatty acid salt, ester, ether or a derivative of a medium chain fatty acid which is, preferably, solid at room temperature and which has a carbon chain length of from 6 to 20 carbon atoms; with the provisos that (i) where the enhancer is an ester of a medium chain fatty acid, said chain length of from 6 to 20 carbon atoms relates to the chain length of the carboxylate moiety, and (ii) where the enhancer is an ether of a medium chain fatty acid, at least one alkoxy group has a carbon chain length of from 6 to 20 carbon atoms.

Preferably, the enhancer is a medium chain fatty acid salt, ester, ether or a derivative of a medium chain fatty acid which is, preferably, solid at room temperature and which has a carbon chain length of from 8 to 14 carbon atoms; with the provisos that (i) where the enhancer is an ester of a medium chain fatty acid, said chain length of from 8 to 14 carbon atoms relates to the chain length of the carboxylate moiety, and (ii) where the enhancer is an ether of a medium chain fatty acid, at least one alkoxy group has a carbon chain length of from 8 to 14 carbon atoms. More preferably, the enhancer is a sodium salt of a medium chain fatty acid, the medium chain fatty acid having a carbon chain length of from 8 to 14 carbon atoms; the sodium salt being solid at room temperature. Most preferably, the enhancer is sodium caprylate, sodium caprate or sodium laurate. The drug and enhancer can be present in a ratio of from 1:100000 to 10:1 (drug:enhancer) preferably, from 1:1000 to 10:1.

In a preferred embodiment of the invention the drug is a macromolecule such as a peptide, protein, oligosaccharide or polysaccharide including TRH, unfractionated heparin, low molecular weight heparin, insulin, luteinising hormone-releasing hormone (LHRH), leuprolide acetate, goserelin, naferelin, buserelin, cyclosporin, calcitonin, vasopressin, desmopressin,an antisense oligonucleotide, alendronate, etidronate or salts thereof.

The solid oral dosage form can be a tablet, a mutiparticulate or a capsule. The multiparticulate can be in the form of a tablet or contained in a capsule. The tablet can be a single or multilayer tablet having compressed multiparticulate in one, all or none of the layers. It is preferably a controlled release dosage form. More preferably, it is a delayed release dosage form. The dosage form can be coated with a polymer, preferably a rate-controlling or a delayed release polymer. The polymer can also be compressed with the enhancer and drug to form a matrix dosage form such as a controlled release matrix dosage form. A polymer coating can then be applied to the matrix dosage form.

Other embodiments of the invention include the process of making the solid oral dosage forms, methods of treating a condition by administering the solid oral dosage forms to a patient and use of a drug and enhancer in the manufacture of a medicament.

DETAILED DESCRIPTION OF THE INVENTION

A number of preferred embodiments of the invention will now be described. In each case the drug may be present in any amount which is sufficient to elicit a therapeutic effect and, where applicable, may be present either substantially in the form of one optically pure enantiomer or as a mixture, racemic or otherwise, of enantiomers. The drug compound is suitably present in any amount sufficient to elicit a therapeutic effect. As will be appreciated by those skilled in the art, the actual amount of drug compound used will depend on the potency of the drug compound in question. The amount of drug compound may suitably be in the range of from about 0.5 .mu.g to about 1000 mg. The enhancer is suitably present in any amount sufficient to allow for uptake of therapeutically effective amounts of the drug via oral administration. Preferably the drug and the enhancer are present in a ratio of from 1:100000 to 10:1 (drug: enhancer), preferably the ratio is from 1:1000 to 10:1. The actual ratio of drug to enhancer used will depend on the potency of the drug compound and the enhancing activity of the enhancer.

In a first embodiment, a solid oral dosage form according to the invention comprises a drug and an enhancer in admixture compressed into a tablet.

In a second embodiment, a solid oral dosage form according to the invention comprises a drug, an enhancer and a rate controlling polymer material in admixture compressed into a tablet. The term "rate controlling polymer material" as used herein includes hydrophilic polymers, hydrophobic polymers and mixtures of hydrophilic and/or hydrophobic polymers that are capable of controlling or retarding the release of the drug compound from a solid oral dosage form of the present invention. Suitable rate controlling polymer materials include those selected from the group consisting of hydroxyalkyl cellulose such as hydroxypropyl cellulose and hydroxypropyl methyl cellulose; poly(ethylene) oxide; alkyl cellulose such as ethyl cellulose and methyl cellulose; carboxymethyl cellulose, hydrophilic cellulose derivatives; polyethylene glycol; polyvinylpyrrolidone; cellulose acetate; cellulose acetate butyrate; cellulose acetate phthalate; cellulose acetate trimellitate; polyvinyl acetate phthalate; hydroxypropylmethyl cellulose phthalate; hydroxypropylmethyl cellulose acetate succinate; polyvinyl acetaldiethylamino acetate; poly(alkylmethacrylate) and poly (vinyl acetate). Other suitable hydrophobic polymers include polymers and/or copolymers derived from acrylic or methacrylic acid and their respective esters, zein, waxes, shellac and hydrogenated vegetable oils. Particularly useful in the practice of the present invention are poly acrylic acid, poly acrylate, poly methacrylic acid and poly methacrylate polymers such as those sold under the Eudragit tradename (Rohm GmbH, Darmstadt, Germany) specifically Eudragit.RTM. L, Eudragit.RTM. S, Eudragit.RTM. RL, Eudragit.RTM. RS coating materials and mixtures thereof. Some of these polymers can be used as delayed release polymers to control the site where the drug is released. They include poly methacrylate polymers such as those sold under the Eudragit tradename (Rohm GmbH, Darmstadt, Germany) specifically Eudragit.RTM. L, Eudragite S, Eudragit.RTM. RL, Eudragit.RTM. RS coating materials and mixtures thereof.

In a third embodiment, a solid oral dosage form according to the invention comprises a multilayer table. Typically such a multilayer tablet may comprise a first layer containing a drug and an enhancer in an instant release form and a second layer containing a drug and an enhancer in a sustained, extended, controlled or modified release form. In an alternative embodiment, a multilayer tablet may comprise a first layer containing a drug and a second layer containing an enhancer. Each layer may independently comprise further excipients chosen to modify the release of the drug or the enhancer. Thus the drug and the enhancer may be released from the respective first and second layers at rates which are the same or different. Alternatively, each layer of the multilayer tablet may comprise both drug and enhancer in the same or different amounts.

A fourth embodiment a solid oral dosage form according to the invention comprises a drug and an enhancer in admixture in the form of a multiparticulate. The drug and enhancer may be contained in the same or different populations of particles, pellets or mini-tablets making up the multiparticulate. If the solid oral dosage form is a multiparticulate, sachets and capsules such as hard or soft gelatin capsules can suitably be used to contain the multiparticulate. A multiparticulate solid oral dosage form according to the invention may comprise a blend of two or more populations of particles, pellets or mini-tablets having different in vitro and/or in vivo release characteristics. For example, a multiparticulate oral dosage form may comprise a blend of an immediate release component and a delayed release component contained in a suitable capsule.

In the case of any of the above-mentioned embodiments, a controlled release coating may be applied to the final dosage form (capsule, tablet, multilayer tablet etc.). The controlled release coating may typically comprise a rate controlling polymer material as defined above. The dissolution characteristics of such a coating material may be pH dependent or independent of pH.

The various embodiments of the solid oral dosage forms of the invention may further comprise auxiliary excipients such as for example diluents, lubricants, disintegrants, plasticisers, anti-tack agents, opacifying agents, pigments, flavourings and such like. As will be appreciated by those skilled in the art, the exact choice of excipients and their relative amounts will depend to some extent on the final dosage form.

Suitable diluents include for example pharmaceutically acceptable inert fillers such as microcrystalline cellulose, lactose, dibasic calcium phosphate, saccharides, and/or mixtures of any of the foregoing. Examples of diluents include microcrystalline cellulose such as that sold under the Trademark Avicel (FMC Corp., Philedelphia, Pa.) for example Avicel.TM. pH101, Avicel.TM. pH102 and Avicel.TM. pH112; lactose such as lactose monohydrate, lactose anhydrous and Pharmatose DCL21; dibasic calcium phosphate such as Emcompress; mannitol; starch; sorbitol; sucrose; and glucose.

Suitable lubricants, including agents that act on the flowability of the powder to be compressed are, for example, colloidal silicon dioxide such as Aerosil.TM. 200; talc; stearic acid, magnesium stearate, and calcium stearate.

Suitable disintegrants include for example lightly crosslinked polyvinyl pyrrolidone, corn starch, potato starch, maize starch and modified starches, croscarmellose sodium, cross-povidone, sodium starch glycolate and combinations and mixtures thereof.
 

Claim 1 of 53 Claims

1. A solid oral dosage form which is effective in delivering a drug and an enhancer, each as defined below, to an intestine and which consists of a pharmaceutical composition consisting of: (A) a therapeutically effective amount of a hydrophilic or macromolecular drug; (B) one or more absorption enhancers, each of which: (i) is a solid at room temperature; (ii) is a salt of a medium chain fatty acid having a carbon length of from 8 to 14 carbon atoms; and (iii) is present in the dosage form such that the ratio of the drug to the one or more absorption enhancers is 1:100,000 to 10:1; (C) one or more excipients selected from the group consisting of rate-controlling polymeric materials, diluents, lubricants, disintegrants, plasticizers, anti-tack agents, opacifying agents, pigments, and flavorings; and optionally, a controlled release coating; wherein the solid oral dosage form is a tablet, a multiparticulate compressible to form a tablet, or a capsule containing a multiparticulate compressible to form a tablet.

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