Patent ID: 8470365

Claim:
A process for preparing a film-coated, multi-layered preparation comprising four anti-tubercular drugs: rifampin, isoniazid, pyrazinamide and ethambutol hydrochloride, which comprises the following steps: (a) individually mixing each of pyrazinamide, isoniazid and ethambutol or each of pharmaceutically acceptable salts thereof with excipients followed by wet granulation of the resulting each mixture with a binder material to obtain granules of said each mixture and thereafter subjecting said granules of each mixture to drying; (b) mixing rifampin or pharmaceutically acceptable salts thereof with excipients to form a powder; (c) preparing two to four pharmaceutical layers by mixing granules of isoniazid or a pharmaceutically acceptable salt thereof of step (a) or rifampin or a pharmaceutically acceptable salt thereof of step (b) and 0 to two pharmaceutical layers comprised of granules of pyrazinamide or a pharmaceutical acceptable salt thereof and ethambutol or a pharmaceutically acceptable salt thereof of step (a) to form two to four pharmaceutical layers so that rifampin or a pharmaceutically acceptable salt thereof and isoniazid or a pharmaceutically acceptable salt thereof are in different layers, wherein the two pharmaceutical layers comprise granules of isoniazid or a pharmaceutical acceptable salt thereof in one layer, rifampin or a pharmaceutical acceptable salt thereof in the other layer and granules of pyrazinamide or a pharmaceutically acceptable salt thereof and ethambutol HCl or a pharmaceutically acceptable salt thereof in either layer, wherein the three pharmaceutical layers comprise granules of isoniazid or a pharmaceutically acceptable salt thereof in one layer, rifampin or a pharmaceutically acceptable salt thereof in another layer and granules of pyrazinamide or a pharmaceutically acceptable salt thereof and ethambutol or a pharmaceutically acceptable salt thereof in any layer to form three layers, or wherein the four pharmaceutical layers comprise granules of isoniazid or a pharmaceutically acceptable salt thereof, rifampin or a pharmaceutically acceptable salt thereof, granules of pyrazinamide or a pharmaceutically acceptable salt thereof, and granules of ethambutol or a pharmaceutical acceptable salt thereof in four separate layers; and (d) compressing the pharmaceutical layers of (c) to obtain a multi-layered preparation, wherein the moisture content of the preparation is less than 1.5%.