Sustained Release of a Hypoglycemic Sulfonylurea from Silicone Rubber Capsules. In-vitro Studies

Abstract

1-(p-Acetyl benzenesulfonyl)-3-cyclohexyl urea, commonly known as acetohexamide, is incorporated into prevulcanized silicone rubber. Capsules in the form of discs 1.5 cm in diameter and 0.22 cm thick, made from the drug-polymer mixtures, are shown to release the drug into water in microgram quantities for a period of over 6 months. The rate of drug release is affected by the total drug content of the capsule as well as the rate of drug removal from the surrounding medium. Capsules with 19 mg of acetohexamide incorporated per disc release 14.2% (2.69 mg) of drug in 200 days while capsules with 38 mg of drug incorporated per disc release 10.9% (4.14 mg) of drug into water during the same period. UV spectra of acetohexamide is scanned to ensure that gross structural changes have not occurred during the course of the experiment. Optical density reading at the 247-nm peak is utilized for the quantitative determination of drug released.