Changing prescription pattern of omeprazole among patients receiving clopidogrel

Recent studies have suggested that omeprazole may reduce the inhibitory effect of clopidogrel on platelet aggregation. The United States Food and Drug Administration (FDA) has issued an update regarding this drug-drug interaction. This study aimed to evaluate the changing prescription pattern of omeprazole in patients taking clopidogrel after the FDA update regarding the clopidogrel-omeprazole interaction. A pharmacy database system was used to identify all prescriptions of clopidogrel alone, clopidogrel and omeprazole, or clopidogrel and ranitidine from May 1, 2009 until May 31, 2010.A total of 2,899 prescriptions were entered into the final data analysis. There was a statistically significant drop in omeprazole prescription with clopidogrel from 46.6% in the period before the FDA update to 38.2% after the update (P = 0.0037). In addition, a significant increase was observed in the ranitidine prescription from 9.7% to 20.1% during the same time frame (P = 0.0059) without any significant change between the two study periods for those on clopidogrel alone without any protective gastrointestinal bleeding drug (43% versus 41.7%). On the other hand, of the 732 patients who were on clopidogrel and omeprazole during the period before the FDA update, 396 patients (54.1%) were taken off omeprazole, 274 (37.4%) were kept on both drugs, 59 (8.1%) had their omeprazole switched to ranitidine after the FDA update, and 3 patients were lost to follow-up (0.4%). The present findings indicate a significant change in prescription pattern for omeprazole after the FDA update by taking patients off omeprazole or to a lesser extent replacing it with ranitidine.