A Pharmacokinetic Model of Drug-Drug Interaction between Clopidogrel and Omeprazole at CYP 2C19 in Humans

Background: Clopidogrel is a thienopryridine antiplatelet agent commonly used in the management of cardiovascular diseases. Clopidogrel is metabolized by hepatic CYP2C19 and CYP2B6, therefore, co-administration of clopidogrel and CYP2C19 inhibitors can alter pharmacokinetics of clopidogrel. Omeprazole is a proton pump inhibitor used for decreasing gastric acid production. Omeprazole is known to be a potent inhibitor of CYP2C19. Thus when the drugs are simultaneously administered, clopidogrel plasma concentration levels can be increased. However, plasma levels of the active metabolite of clopidogrel can be significantly decreased, thereby, its antiplatelet activity is reduced. Objectives: We aimed to develop a mathematical model describing a drug-drug interaction between clopidogrel and omeprazole in humans. Methods: Searching for pharmacokinetic interaction studies between clopidogrel and omeprazole in humans was performed in PubMed. Six studies were selected into our modeling purposes to develop 3 mathematical models (i.e. 4 studies for clopidogrel alone, 1 study for omeprazole alone and 1 study for clopidogrel-omeprazole interaction). Subsequently, concentration-time course data from the selected studies were extracted. Computer codes and simulations were performed using the Advanced Continuous Simulating Language Extreme (ACSLX) program. Results: We successfully developed 3 mathematical models which are able to describe all of the datasets. Conclusions: Our clopidogrel-omeprazole pharmacokinetic interaction model with a description of competitive inhibition at CYP2C19 could successfully describe concentration-time courses from the selected datasets. Our interaction model may be useful in predicting plasma levels of clopidogrel and its active metabolite.