Sustained released pharmaceutical compositions

Claim 2

A MATRIX SUITABLE FOR FORMULATING A SUSTAINED RELEASE PHARMACEUTICAL COMPOSITION, SAID MATRIX CONSISTING ESSENTIALLY OF FROM ABOUT 80% - 98% BY WEIGHT OF ACETYLSALICYLIC ACID OR A PHARMACEUTICALLY ACCEPTABLE SALT OR COMPLEX THEREOF, DIMETHYL POLYSILOXANE HAVING A VISCOSITY OF 20,000 TO 150,000CPS AND A CELLULOSE DERIVATIVE SELECTED FROM THE GROUP CONSISTING OF WATER-INSOLUBLE LOW VISCOSITY CELLULOSE ETHER OR ESTER, THE WEIGHT RATIO OF SAID CELLULOSE DERIVATIVE TO SAID POLYSILOXANE BEING WITHIN THE RANGE OF FROM 10:1 TO 1:1.

Claim 3

A matrix according to claim 1 suitable for formulation into sustained release pharmaceutical compositions containing 0.1 to 1.0g of acetylsalicylic acid per dosage unit, said matrix being in the form of pellets or granules for filling into dosage units of hard gelatine capsules or pediatric gel sachets having sugar and flavoring, for use with water, or formed into tablet dosage units with starch, glyceryl palmito-stearate, talc and microcrystalline cellulose tableting excipients, said pellet or granule matrix being conveniently 80-98% by weight of acetylsalicylic acid, said matrix being in the form of a. pellets, suitable for filling hard gelatine capsules or pediatric gel sachets, having sugar and flavoring, for use with water, said pellets having been obtained by being centrifuged before evaporating solvent and drying under vacuum from extruded granules, cut to 1mm length from strands formed by extrusion from an extruder wherein the extrusion orifices are about 0.5mm to 2.5mm in diameter of a pasty mass obtained by evaporating off solvent after thorough mixing of powdered 80 mesh acetylsalicylic acid, a solution of dimethylpolysiloxane, 20,000 to 150,000cps, in a nonaqUeous solvent therefore, in which solvent the acetylsalicylic acid itself is insoluble, said solvent being selected from the group consisting of methylene chloride, chloroform, carbon tetrachloride, benzene, toluene and mixtures thereof and a solution in said non-aqueous solvent of ethoxyl ethylcellulose having a viscosity of 9-11cps when 70g are dissolved in 300ml of 1:1 (v/v) mixture of toluene-methylenechloride, the proportion of ethylcellulose to polysiloxane employed in the matrix being in a weight ratio ranging from 10:1 to 1:1; or b. granules obtained from said extruded strand cut to 1mm length hardened with dry air and dried under vacuum until the solvent is completely removed.

Claim 4

A matrix according to claim 1 wherein the amount of acetylsalicylic acid in said matrix is 88-94% by weight thereof.

Claim 5

A matrix according to claim 1 wherein the said cellulose derivative used to form said matrix is selected from the group consisting of ethyl cellulose and cellulose acetobutyrate.

Claim 6

A matrix according to claim 4 wherein the said ethyl cellulose has a viscosity of 18 to 22 cps when measured in a 5% by weight solution thereof in a 80/20 toluene/ethanol mixture at 25*C.

Claim 7

A pharmaceutical composition comprising the matrix of claim 1 having added thereto acetylsalicylic acid or a pharmaceutically acceptable salt or complex thereof in free form.