793,808. Sustained action pills. BARDANI, F. M. July 21, 1955 [July 22, 1954; July 8, 1955], No. 21166/55. Class 81 (1). A pill which releases medicament in a sustained manner in the stomach comprises a unitary mass of medicament coated or enclosed by a mixture forming a filter insoluble in but penetrable by stomach fluids after exposure thereto for a predetermined time and which may comprise 80 to 95 per cent by weight of a cellulose derivative containing free carboxylic groups and 20 to 5 per cent by weight of wax, e.g. beeswax or carnauba wax, the fluids leaching the medicament out through the filter over an extended time interval of at least one hour, the filter remaining intact at least until all the medicament has been leached therethrough. The cellulose derivative may be a cellulose ester of a polycarboxylic acid in which at least one carboxylic acid group remains unesterified, one or more of the remaining carboxylic acid groups being esterified with one or more hydroxyl groups of the cellulose, rendering the coating soluble in intestinal fluids. The cellulose derivative may be formed by acylation of a cellulose ether or ester having free hydroxyl groups with a polycarboxylic acid to form an ester linkage and leave one free carboxylic acid group on the polycarboxylic acid. Examples are cellulose acetate phthalate, cellulose propionate succinate and cellulose acetate butyrate maleate. A similar pill which releases medicament in the intestines is formed by coating a unitary mass of medicament with a mixture forming a filter unaffected by exposure to stomach fluids and insoluble in but penetrable by intestinal fluids after exposure thereto for a predetermined time and which may comprise 80 to 95 per cent by weight of a cellulose ether, e.g. ethyl cellulose, and 20 to 5 per cent by weight of a sealer, e.g. shellac. The sealer may be replaced by a small percentage, e.g. 0.5 per cent, of wax. As shown in Figs. 2 and 3, either or a mixture of both types of pills 10 may be mixed with powder sugar, magnesium sulphate, starch, effervescent powders, e.g. citric or tartaric acid and sodium bicarbonate, or laxatives, to form tablets 22 and 23. In a modification of the invention shown in Fig. 1, a pill 10 which selectively releases medicament in a sustained manner in the alimentary canal comprises a medicament core 21, is coated with a mixture forming a filter 20 unaffected by exposure to stomach fluids and insoluble in but penetrable by intestinal fluids. Coating 20 is enclosed within medicament layer 19 which is coated with a similar filter material 18. Similarly, coating 18 is enclosed within medicament layer 17 coated with filter material 16 similar to coatings 18 and 20. Coating 16 is enclosed within medicament layer 15 which is coated with a mixture forming a filter 14 insoluble in but penetrable by stomach fluids after exposure thereto for a predetermined time and soluble in intestinal fluids. Coating 14 is enclosed within medicament layer 13 which has a filter coating 12 similar to coating 14. Coating 12 is enclosed within outer medicament layer 11 which may be sugar coated or have a coating of polished wax which may be coloured. The medicament in each layer may be the same, or different layers may contain different medicaments. Medicaments specified are antibiotics, e.g. penicillin, hypnotics, e.g. pentobarbital sodium, hypotensives, e.g. dextro-amphetamine sulphate, vasodilators, amines or hormones.