WO2007143959A2

WO2007143959A2 - Tablet containing metformin

Info

Publication number: WO2007143959A2
Application number: PCT/CZ2007/000056
Authority: WO
Inventors: Juraj Zeleznik; Beata Vladovicova; Viera Kormanova; Viera Hubinova; Mikulas Lehocky
Original assignee: Zentiva, A. S.
Priority date: 2006-06-16
Filing date: 2007-06-18
Publication date: 2007-12-21
Also published as: WO2007143959A3; CZ300698B6; CZ2006392A3

Abstract

Tablet containing metformin or pharmacologically acceptable salts thereof, where the active substance release is controlled by a hydrophobic polymer; the tablet contains 60 to 80 percent by weight of the active substance and 9 to 25 percent by weight of the hydrophobic polymer.

Description

Tablet containing metformin

Technical Field

The invention concerns metformin tablets with a novel controlled release feature.

Background Art

Metformin is an antihyperglycemic drug from the biguanide class, used for the treatment of non insulin dependent diabetes mellitus (NIDDM).

Metformin is absorbed by the upper part of the digestive tract solely; its biological availability is 40% to 60% but it decreases with increasing dose. Its solubility is very high (> 300 mg mL at 25°C). This brings about problems with the initial rapid release of the active component into the digestive tract. A relatively high metformin dose is a problem as well.

If a controlled-release drug is highly soluble, a large amount is usually released at the very beginning, thereby lowering or even disturbing the controlled-release effect. The release process is only stabilized after the matrix-constituting polymer has undergone hydration. From this point of view, a hydrophilic, fast-hydrating polymer would be best suited for metformin, for the steady state to establish as soon as possible and the controlled-release effect to be disturbed as little as possible.

Patent application WO 9947128 addresses this problem through a phase system where the internal phase in the granulate form comprises the active substance and a matrix consisting of a hydrophilic or hydrophobic substance such as an ethyl cellulose/hydroxypropylmethyl cellulose mixture. The particles are combined into a continuous phase where a next matrix is also formed by a hydrophilic or hydrophobic polymer, such as hydroxypropylmethyl cellulose.

It will be clear at first glance that such systems for high-solubility substances, specifically for metformin, are very complex and their simplification is desirable.

Disclosure of Invention

The present invention provides a metformin-containing tablet with modified release controlled by a hydrophobic polymer. In the invention, the tablet comprises metformin, or a pharmacologically acceptable salt thereof, in an amount of 60 wt. % to 80 wt. %, and 9 wt. % to 25 wt. % of a hydrophobic polymer. An acrylic polymer is preferably used as the hydrophobic polymer. The invention also provides a process of production, which comprises mixing of particiBTor grains of a metformin granulate with a film of the hydrophobic polymer, followed by compressing into tablets. During this process, the particles are suitably wrapped into, or coated with, the hydrophobic polymer. Metformin particles with the optimal grain size are obtained by dry granulation or by wet granulation or by pelletizing. The hydrophobic polymer is applied to the metformin-contaming particles in a fluidized-bed granulator or in a stirred or high-revolution granulator. The hydrophobic polymer forms a continuous film, and the specific polymer type preferably ensures that the film is plastic and will not be damaged during the compression process. To produce such a tablet it is convenient to prepare a mixture containing 80 wt.% to 100 wt.% metformin, preferably in the hydrochloride form, to which the hydrophobic polymer, preferably a neutral acrylic polymer, is applied in amounts of 10 wt.% to 20 wt.%. Metformin can be granulated by using a solution of a binder, whereby an optimum grain size is obtained. Polyvinylpyrrolidone in amounts of 3 wt. % to 10 % is preferably used as the binder. As additional excipients, the tablet mixture further contains substances improving the flow properties and anti-adhesives improving the slip properties of the mixture and thus facilitating the tabletting process. Colloidal silica is the most preferable material to improve the flow properties of the tablet mixture, preferably in amounts of 0.1 wt.% to 5 wt.%; suitable antL- adhesives include stearic acid salts, particularly magnesium stearate, and talc, preferably in amounts of 0.1 wt.% to 10 wt.%.

The tablet manufacturing process and choice of excipients according to the present invention make it possible to prepare solid retarded-release drug form featuring outstanding physical parameters and the desired dissolution profile. This drug form is easier to prepare and has a higher active content that the presently widely used Glucophage product.

Examples Example 1 Metformin XR 500

The tablet preparation procedure comprised the following steps:

1. Active substance granulation by using a polyvinylpyrrolidone solution

2. Granulate grain drying and size modification

3. Granulate grain coating with a suspension of the ethyl acrylate-methyl methacrylate copolymer and talc 4. Homogenization of the coated granulate with a final treatment of the tablet mass - colloidal silica and magnesium stearate 5. Tabletting

The dissolution profile is a significant parameter of controlled-release tablets. The dissolution profile of the tablets manufactured as described above is in a very good agreement with that of Merck's already approved and sold product Glucophage XR 500 mg, whose composition is in accordance with WO 99/47128.

The dissolution profile was measured by the standard procedure (900 ml, phosphate buffer pH 6.8, 100 rpm, baskets, UV determination).

The dissolution data for the Metformin XR 500 tablets, in time intervals comparable to Glucophage XR 500 mg, are given in the table below:

Example 2

Metformin XR 500

Dependence of the release rate on the amount of the release-retarding substance:

The tablet preparation procedure comprised the following steps:

1. Active substance granulation by using a polyvinylpyrrolidone solution

2. Granulate grain drying and size modification

3. Granulate grain coating with a suspension of the ethyl acrylate-methyl methacrylate copolymer and talc

4. Homogenization of the coated granulate with a final treatment of the tablet mass — colloidal silica and magnesium stearate

5. Tabletting

The dissolution profile was measured by the standard procedure (900 ml, phosphate buffer pH 6.8, 75 rpm, baskets, UV determination). Dissolution profiles:

The active substance release rate depends on the amount of release-retarding substance present: the higher the release-retarding substance content, the slower the release of metformin hydrochloride into the environment.

Claims

1. Tablet containing metformin or pharmacologically acceptable salts thereof, where the active substance release is controlled by a hydrophobic polymer, wherein the tablet contains 60 to 80 percent by weight of the active substance and 9 to 25 percent by weight of the hydrophobic polymer.

2. Tablet as claimed in Claim 1, wherein the hydrophobic polymer is a neutral acrylic polymer.

3. Tablet as claimed in any of the preceding claims, wherein the tablet contains 60 to 80 percent by weight of the active substance, 9 to 25 percent by weight of the hydrophobic polymer and 3 to 10 percent by weight of a binder, preferably polyvinylpyrrolidone.

4. Tablet as claimed in any of the preceding claims, wherein the tablet further contains 0.1 to 5 percent by weight of a substance improving the flow properties of the tablet mixture mass, such as colloidal silica, and/or 0.1 to 10 percent by weight of a substance improving the slip properties of the tablet mixture mass, selected from stearic acid salts and/or talc.

5. Tablet as claimed in any of the preceding claims, wherein the tablet contains 500 mg to 750 mg of metformin hydrochloride as the active substance and 100 mg to 200 mg of the ethyl acrylate-methyl methacrylate copolymer.

6. Process for the production of tablets as claimed in the preceding claims, comprising: preparing a granulate containing metformin, optionally along with other pharmaceutically acceptable substances, by one of the following methods: a. dry granulation, b. wet granulation, c. pelletizing, mixing the granulate with the hydrophobic polymer either a. in a fluidized-bed granulator or b. in a stirred granulator, and compressing the obtained mixture.

7. Process as claimed in Claim 6, comprising wet granulation, followed by wet mixing.

8. Process as claimed in Claim 7, comprising drying the granulate, followed by coating with the polymer, and drying again.

9. Process as claimed in Claim 6, comprising compression of the coated granulate particles.

10. Process as claimed in Claim 9, wherein the particular type and amount of the hydrophobic polymer is selected with respect to the starting granulate so that the coating layer is not disturbed during the compression step.

11. Process as claimed in Claim 10, wherein the core of the granulate contains 80 to 100 percent by weight of the active substance and the coating material contains 80 to 100 percent by weight of a neutral acrylate polymer.