Kinetics of Omeprazole Release from Enteric Dosage Forms of Different Manufacturers

A comparative dissolution kinetics test (CDKT) related to proton-pump inhibitors (PPIs), particularly omeprazole, using dissolution media with pH 1.2 and 6.8 does not take into account the impact of common pathophysiological factors on these acid-labile drugs, in particular pharmacological acid suppression of intragastric contents in patients with acid-dependent diseases. The stability of enteric dosage forms in moderately acidic environments (pH 4.0) should be studied to solve this problem because they simulate the gastric content during a course of PPIs, i.e., they themselves organize stress testing of their own membranes after several days of a course of PPIs, the results of which can be predictively assessed in CDKT studies. ACDKT was performed on a model of pharmacological acid suppression using the drugs OMEZ ® (20 mg enteric capsules, Dr. Reddy’s Laboratories LLC, Spain) and omeprazole enteric capsules (20 mg) produced in Russia with a stated bioavailability of 30 – 40% (Omeprazole * ). The drugs OMEZ ® and Omeprazole * were pharmaceutically equivalent when exposed to a solution with a pH of 6.8 after incubation for 2 h in a medium with pH 1.2. However, destruction of Omeprazole * granules was observed with probable degradation of the released acid-labile active substance in the moderately acidic environment after exposure to a solution with pH 4.0. The proportion of the released active substance did not exceed 24.0%, as compared to 82.4 – 88.1% of the active substance released from OMEZ* granules, when the partially destroyed granules were transferred into a solution with pH 6.8, simulating the environment of the small intestine. Consequently, enteric granules of the drug Omeprazole * , in contrast to granules of the drug OMEZ ® , were destroyed in a moderately acidic environment with pH 4.0 corresponding to the pH of the stomach during a course of PPI use with a decrease in the concentration of the acid-labile active substance omeprazole in media simulating the environment of the stomach and small intestine.