A survey of the stability of omeprazole products from 13 countries

The results of an independent survey of the stability of omeprazole solid dosage forms (20 mg) show that products available in many countries worldwide exhibit a very wide range of stability characteristics. Stability testing under the ICH accelerated test conditions (40 degrees C/75% RH; 6 months) was performed on a total of 34 products obtained in 13 countries by independent sampling officers. The samples were visually examined for physical change and analyzed for their total content of impurities, remaining omeprazole, and the amount of omeprazole released in vitro. Twenty-seven of the products (79%) exhibited a change in one or more of the stability-indicating parameters during the 6-month study. These included 16 products that had more than 10% of decomposition products at 6 months and 10 other products that contained 2-10% of decomposition products at 6 months. In most samples, the formation of decomposition products was accompanied by a corresponding measurable decrease in the content of omeprazole. Of the eight samples containing less than 2% of decomposition products after 6 months storage, one showed a large reduction in the amount of omeprazole released in vitro. Another product which contained 1.2% decomposition products at 6 months released lower amounts of omeprazole in vitro at all time points than most other products. Only six products (18%) were considered to demonstrate good physical and chemical stability over the course of the study, viz. Losec Capsules (Astra, Sweden), Losec Capsules (Astra, Korea), Losec Capsules (Astra, Turkey), Miracid Capsules (Berlin Pharm. Ind. Co., Thailand), Mopral Capsules (Astra-Ifesa, Spain), and OMP Tablets (Chon Kun Dang Corp., Korea).