Title:  Opioid analgesic

United States Patent:  6,806,294

Issued:  October 19, 2004

Inventors:  Wimmer; Walter (Limburg, DE); Brogmann; Bianca (Limburg-Eschhofen, DE); Hahn; Udo (Nentershausen, DE); Spitzley; Christof (Elbtal-Heuchelheim, DE)

Assignee:  Euro-Celtique S.A. (Luxembourg, LU)

Appl. No.:  128632

Filed:  April 23, 2002

Abstract

The invention is relative to a pharmaceutical preparation, especially for oral administration, with at least one active substance and with formulation components influencing the release of active substance, which preparation comprises at least one opiod analgesic as active substance that is formulated proportionally on the one hand for rapid release and on the other hand for delayed release in such a manner that the in vitro release rate from the preparation according to the Ph. Eur. paddle test shows a mean value of above 40% by weight after one hour and that the in vitro release rate shows a mean value that is still below 80% by weight after four hours.

Description of the Invention

The invention is relative to a pharmaceutical preparation, especially for oral administration, with at least one active substance and with formulation components influencing the release of active substance, which preparation comprises at least one opiod analgesic as active substance that is formulated proportionally on the one hand for rapid release and on the other hand for delayed release. The invention is especially relative to pharmaceutical preparations containing tramadol or a pharmaceutically compatible salt of tramadol, especially tramadol hydrochloride, as active substance.

So-called "multiphase" pharmaceutical preparations in which the active-substance content is formulated on the one hand for a rapid release and on the other hand for a delayed (retarded) release have long been known. Such preparations have also already been frequently described for analgesics.

EP-A 0,243,366 teaches a sustained-[controlled-]release formulation for tramadol that is suitable for a uniform and long-lasting release of the active substance over twenty-four hours or longer.

EP-A 1 0,642,788 teaches pharmaceutical preparations in tablet form containing a tramadol salt as active substance that is present in a matrix for the delayed release of active substance. Cellulose ether[s] and/or cellulose ester[s] are an essential component of this matrix and exhibit a viscosity between 300 and 150,000 mPas in a 2% by wt. aqueous solution at 20^oC. It is pointed out in the specification that the tablet core, that contains the matrix containing the active substance, can be encased with additional active substance that is not delayed and is therefore rapidly released. Multi-layer tablets and laminated tablets are cited as examples.

Multiphase tramadol preparations art commercially available. The product "Tramadolor ID 100" of Hexal AG, that contains tramadol on the one hand in sustained-release formulation and on the other hand in a rapid-release formulation is an example thereof. However, the in vitro release data as well as the blood plasma level development in time correspond to a relatively slow initial flooding, so that the start of the desired analgesic action after administration of the preparation does not always take place as rapidly as would be desired.

EP-A2 0,864,325 recently disclosed another two-phase preparation containing an opiod analgesic, e.g., tramadol hydrochloride, in sustained-release and rapid release formulation. According to this publication the in vitro release rate (determined according to the paddle test described in Ph. Eur.) is extremely high; at least 50% by wt. of the active substance is released from the preparation within one hour in vitro. The examples of EP-A2 0,864,325 even correspond in part to much greater release rates: After two hours approximately 70% by wt. and after four hours approximately 90% by wt. of the active substance has been released and after six hours the release of active substance is practically concluded.

This corresponds to an extremely rapid buildup of a high plasma level of the active substance and to a correspondingly very rapidly beginning analgesic action.

However, it is indicated on the other hand in EP-A2 0,864,325 that after a one-time application under fasting conditions blood plasma levels of 90 to 200 ng/ml and in the preferred range blood plasma levels of far above 100 ng/ml were still found after five hours.

The active-substance dosage applied in a one-time manner to which this blood plasma level development corresponds is not indicated in the application. However, it can be deduced from a consideration of the magnitude [size], that such high plasma level values after five hours are only possible, in view of the extremely rapid total release of the active substance from the preparation, if the dosing of the active substance in the unit [standard] dosage is very high. The data in EP-A2 0,864,325 probably corresponds to a unit dose of 200 mg active substance. Since a twice daily application is provided, the maximum daily dose of 400 mg given in the tramadol monograph of the Federal Health Office dated 1994 is not exceeded (but is reached) at such a high amount of active substance in the unit dose; however, this also means that the patient is exposed for hours to a very high concentration of active substance in the time between the first attainment of the analgetically active concentration on the one hand and the dropping of the plasma level below the analgetically active concentration on the other hand, which very high concentration of active substance is far above that necessary for analgetic action.

On the other hand, it also follows from the data of this application that the action in the sense of a freedom from pain in the patient can not last twelve hours. The very rapid total release of the active substance also corresponds to a correspondingly short half-life W₅₀. Thus, in the case of a twice-daily administration the patient is supplied with too much active substance for hours and subsequently with too little active substance for several hours.

In view of this state of the art, a significant problem of the invention is to create a pharmaceutical preparation of the initially cited type that combines the most rapid possible start of the analgetic action with the longest possible duration of action while avoiding high plasma concentrations of the active substance in the interim.

The invention has the further significant problem of creating such a preparation of the initially cited type that makes possible a uniform and sufficiently analgetic action over the entire 24-hour period at a dosage of twice to three times daily.

Further problems and advantages of the invention result from the following description.

Preparations preferred in accordance with the invention comprise as active substance at least an opiod analgesic, preferably bupivacaine, buprenorphine, clofenadol, codeine, dextromoramide, diamorphine, dihydrocodeine, dihydromorphine, ethylmorphine, fentanyl, hydrocodone, hydromorphone, levomethadone, meperidine, methadone, morphine, nalbuphine, nefopam, normethadone, oxycodone, oxymorphone, pentazocine, pethidine, phenpyramide, piritramide, propoxyphene, tebacone, tilidine, tramadol and/or their physiologically compatible salts as well as derivatives of the previously cited active substances.

The invention basically solves the problem, according to the features of the independent claims, with the formulation of the pharmaceutical preparation in such a manner that the opioid analgesic contained in the preparation, in particular a tramadol salt such as tramadol hydrochloride, is in part formulated for a rapid release and in part for a delayed release in such a manner that the in vitro release rate from the preparation according to the paddle test in accordance with Ph. Eur. shows a mean value [an average value] of more than 40% by wt. already after one hour but on the other hand 80% by wt. active substance had not yet been achieved after four hours under the same test conditions.

In a preferred embodiment of the invention more than 70% by wt. of the active substance has already been released after four hours in vitro. After seven to ten hours, and especially preferably after approximately eight hours approximately 90% by wt. of the active substance has been released in vitro. However, it is preferable if a complete release has not yet been achieved after fourteen hours, in particular not yet after sixteen hours.

In comparison to EP-A2 0,864,325, the initial course of the release up to approximately one hour is similar. The release after one hour attains 40% by wt. in every instance but must not attain the 50% by wt. prescribed in the state of the art. However, it is possible and is also preferred if the release in vitro has a mean value of approximately 50% by weight or even more according to the mentioned paddle test.

This can be achieved by appropriately adjusting the release rate. To this end, especially the type and amount of the disintegrant worked into the rapid-release component of the preparation is to be used. In principle, the amount of active substance released within the first hour in the agent in the paddle test can be increased by increasing the amount of disintegrant. Disintegrants suitable in accordance with the invention preferably comprise a polymer and especially preferably cross-linked polyvinylpyrrolidone (PVP).

The release curve then differs very clearly from the teaching of EP-A2 0,864,325 especially in the time after two hours after administration. The release takes place, substantially from the sustained-release component of the preparation, very much slower and up to approximately the complete release a preferred preparation in accordance with the invention takes more than twice as long (more than sixteen hours in comparison to approximately eight hours) as according to EP-A2 0,864,325.

The principle of the invention can also be defined via the plasma levels of the active substance, that are measured after a one-time administration of a preparation of the invention in the agent using a plurality of test subjects. The development in time of the plasma level of the active substance for a preparation in accordance with the invention is approximately as follows:

The further development in time then corresponds to the following:

These values refer to the one-time administration of a dose of 100 mg of the analgesic, especially tramadol hydrochloride. The absolute values of the plasma level are naturally dependent on the given dose. However, the development in time of the plasma level corresponds substantially to the above values even in the case of other one-time dosages than 100 mg analgesic as regards their curve shape, taking appropriate account of the different dosing.

Preparations in accordance with the invention make possible an average half-life W₅₀ (relative again to a one-time application of 100 mg active substance) of more than five hours, preferably of more than six hours and especially preferably more than seven hours.

The pharmaceutical preparations of the invention contain at least one active substance and their active-substance component contains at least one opiod analgesic. Pharmaceutical preparations of the invention can also contain more than one opiod analgesic and can also contain other active substances in addition to one or more opiod analgesics. Other active substances that can be combined with opiod analgesics are known in the state of the art.

The analgesics that can be contained in the preparations of the invention correspond to the active substances indicated in the initially cited state of the art, in particular to the opiod analgesics cited in EP-A2 0,864,325. Tramadol, especially in the form of tramadol hydrochloride, is especially preferred as active substance.

The analgesic active substance, especially preferably an opiod, is preferably distributed in a nonuniform manner onto the two "phases" of the preparation, that release at different rates, in such a manner that the relatively greater part of the active substance is formulated for delayed release. Generally speaking, therefore, the amount of the analgesic in the rapidly releasing phase of the preparation is less than 50% and the amount of the active substance in a sustained-release matrix is greater than 50% relative to the total content of analgesic active substance in the preparation. It is especially preferable if the relative amounts of the active substance in the rapid-release "phase" and in the delayed-release "phase" of the tablets are in the approximate ratio of 1:3 to 1:5. This corresponds in a tablet in accordance with the invention with a total of 100 mg tramadol hydrochloride and at a ratio of 1:3 to a distribution of 25 mg tramadol hydrochloride in the rapid-release component and 75 mg tramadol hydrochloride in the delayed-release component of each tablet.

Whereas the preferred unit dose of the analgesic, especially for tramadol hydrochloride, is approximately 100 mg, it can deviate from this. The active-substance content of a preparation in accordance with the invention is generally between 20 and 500 mg, especially between 50 and 200 mg in a unit dose. High dosages are less preferable since the invention makes it possible to combine a rapid flooding with a long-lasting duration of action without the maximum concentration of active substance in the blood of the patient reaching undesirably high values.

The preparations of the invention are preferably solid medicinal forms. Tablets, especially bilaminar tablets are especially preferred. The delayed-release component of the analgesic, preferably an opiod, is then located in one layer whereas the rapid-release component is taken up in the other layer. The tablet is then preferably provided with an external coating that imparts properties to it that are on the whole neutral in taste.

The rapid-release part of the pharmaceutical preparation of the invention comprises a potent disintegrant formed in particular from a polymer. At the present, a cross-linked PVP is especially preferable. The amount of disintegrant in the rapid-release part of the preparation must be dimensioned in such a manner that the desired rapid release and therewith the rapid flooding of the active substance are achieved. The amount of disintegrant therefore corresponds to at least 10% by weight of the total mass (including the amount of active substance) of the rapid-release "phase" of the preparation. Often, the amount corresponds to at least 20% by weight, preferably at least 25% by weight and especially preferably at least 30% by weight, relative again to the mass of the part of the preparation of the invention constituting the formulation of the rapid-release active substance. In order to achieve an specially strong flooding and a corresponding, initial release of active substance, the amount of disintegrant can also be above 30% by weight; in an especially preferred embodiment of the invention it is approximately 32% by weight, relative again to the same basis.

In addition to the cited amount of disintegrant, cross-linked PVP in particular, such a rapid-release formulation in accordance with the invention also contains the rapid-release amount of the active substance, e.g., 25 mg tramadol hydrochloride in a 100 mg tramadol tablet. Furthermore, the rapid-release formulation preferably contains a lactose hydrate such as, in particular, lactose monohydrate, whose amount can also be up to approximately 30% by weight relative to the total mass of the rapid-release part of the preparation.

Further components such as, e.g., binders (preferably polyvidone), magnesium stearate and the like can be added in customary amounts. The rapid-release component of the preparation contains a small amount (approximately 1 mg) purified water in addition in the most-preferred embodiment.

The sustained-release matrix, that is provided, e.g., in the second layer of a bilaminar tablet in accordance with the invention, basically corresponds to the sustained-release matrixes for opiod analgesics such as tramadol in particular, which matrixes are already known in the state of the art. They can be formed in accordance with EP-A1 0,624,366 (already cited). The compounds indicated in it can also be used as sustained-release matrix for the present invention either in general or as an exemplary embodiment.

For example, in a currently especially preferred embodiment the compound of a preparation in accordance with the invention formulated for delayed release contains a mixture of lactose monohydrate, ethylcellulose with low viscosity and cetostearyl alcohol as main components in addition to the appropriate amount of active substance (thus, 75 mg active substance, especially tramadol hydrochloride in a 100 mg tablet). In addition, other formulation aids can be added that are known in the state of the art.

The production of preparations in accordance with the invention takes place according to methods known and described in the state of the art. For example, tablets in the sense of preparations in accordance with the invention can be produced according to the methods described in EP-B1 0,642,788 (already cited).

An especially important indication for preparations in accordance with the invention is acute pain therapy. Such preparations can be used with particular advantage in this instance instead of the currently customary drops on account of the rapid and high flooding.

Claim 1 of 12 Claims

What is claimed is:

1. A pharmaceutical preparation for oral administration comprising a bilaminar tablet comprising a rapid release layer comprising tramadol or a pharmaceutically acceptable salt thereof, polyvinylpyrrolidine and microcrystalline cellulose; and a delayed release layer comprising tramadol or a pharmaceutically acceptable salt thereof, ethylcellulose, and cetostearyl alcohol said preparation exhibiting an in vitro release rate according to the Ph. Eur. paddle test of a mean value of above 40% by weight after one hour and a mean value of below 80% by weight after four hours.

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