A summary of Food and Drug Administration-reported adverse events and drug interactions occurring during therapy with omeprazole, lansoprazole and pantoprazole

Background: Pantoprazole is claimed to have a lower potential for drug interaction than other proton pump inhibitors. Aim: To estimate the frequency of adverse events and drug interactions reported to the Food and Drug Administration in patients receiving omeprazole, lansoprazole or pantoprazole. Methods: The study involved a search of the Food and Drug Administration's database for adverse events and drug interactions with omeprazole, lansoprazole or pantoprazole as primary or secondary suspect drug. An estimate of the amount of drug dispensed during the adverse event collection period (from US drug launch) was obtained from the International Medical Statistics health database. Results: Of the suspected drug interactions recorded, vitamin K antagonist interactions, although rare, were the most common. The frequency of vitamin K antagonist interactions was 0.09 per million packages for omeprazole and 0.11 per million packages for lansoprazole and pantoprazole. Interactions with benzodiazepines or phenytoin were even rarer, being reported in less than 10 patients on each proton pump inhibitor. Conclusion: The frequency of reported drug interactions was low for omeprazole, lansoprazole and pantoprazole and vitamin K antagonist interactions were by far the most common. These potentially important drug interactions, although rare, were no less frequent on pantoprazole than on omeprazole or lansoprazole, suggesting a class effect.