Patent GB-428941-A (GB)
Title: Process of protecting medicaments from the action of stomach-juices
IPC: A61K9/28
Filed: 1933-11-22
Abstract: Coatings for medicaments comprise a water-insoluble polymeric carboxylic acid or a derivative thereof which is easily hydrolyzable. Suitable polymeric acids are polystyrenemaleic acid, polyacrylic acid or derivatives, such as esters of these acids.  The stability of such films and coatings may be increased by the addition thereto of water-repellent substances such a nonvolatile esters and ethers, hydrocarbons and anhydrides of the higher fatty acids.  In examples: (1) a film is prepared by dissolving a 1 to 1 polymerisate of vinylbutyl ether and maleic anhydride in aqueous caustic soda, precipitating the free acid, drying and dissolving in methanol and/or acetone; (2) a film is prepared from a solution of the polymerisate from a mixture of acrylic acid nitrile and acrylic acid methyl ester, to which is added five per cent of coco-nut oil fatty acids; the polymerisate is prepared by polymerizing a mixture of 10 parts of acrylic acid nitrile and 90 parts of acrylic acid methyl ester in acetone-methanol solution containing potassium hydroxide and the acid liberated from the resulting potassium salt by treatment with acetic acid; (3) a polymerisate, obtained from 90 parts of acrylic acid butyl ester and 10 parts of styrene, is saponified with potassium hydroxide and the resulting salt converted into free acid by treatment with acetic acid and dissolved in acetone or methanol; (4) a solution of a product from the polymerization of a mixture of styrene and maleic anhydride is mixed with a pancreas enzyme preparation.ALSO:Medicines are protected from solution in the acid juices of the stomach but allowed to dissolve in the alkaline fluids of the intestine by coating or enclosing them in a water insoluble polymeric carboxylic acid or a derivative thereof which is easily hydrolyzable in the alkaline liquids mentioned.  Suitable polymeric acids are polystyrenemaleic acid, polyacrylic acid or derivatives, such as esters of these acids.  The stability of such films and coatings may be increased by the addition thereto of water repellent substances such as nonvolatile esters and ethers, hydrocarbons and anhydrides of the higher fatty acids.  Example 1. A film is prepared by dissolving a 1 to 1 polymerisate of vinylbutyl ether and maleic anhydride in aqueous caustic soda, precipitating the free acid, drying and dissolving in methanol and/or acetone.  Example 2.  A film is prepared from a solution of the polymerisate from a mixture of acrylic acid nitrile and acrylic acid methyl ester, to which is added five per cent of coco-nut oil fatty acids.  The polymerisate is prepared by polymerizing a mixture of 10 parts of acrylic acid nitrile and 90 parts of acrylic acid methyl ester in acetonemethanol solution containing potassium hydroxide.  The acid is obtained from the resulting potassium salt by treatment with acetic acid.  Example 3.  A polymerisate, obtained from 90 parts of acrylic acid butyl ester and 10 parts of styrene, is saponified with potassium hydroxide and the resulting salt converted into free acid by treatment with acetic acid and dissolved in acetone or methanol. Example 4.  A solution of a product from the polymerization of a mixture of styrene and maleic anhydride is mixed with a pancreas enzyme preparation to give a product on evaporation which will pass the stomach and dissolve in the intestine.