Clopidogrel and the possibility of drugedrug interaction in primary health care

Introduction: Clopidogrel ineffectiveness is a serious problem in antiplatelet therapy. Many factors may contribute to this phenomenon. One of them is clopidogrel drugedrug interaction with CYP2C19 and CYP3A4 enzyme inhibitors. The main goal of this descriptive study was to assess the prevalence of cases of clopidogreledrug interactions in the primary health care physicians’ practices. Materials and methods: During 2010-2011, 80 patients receiving clopidogrel antiplatelet therapy from primary care physicians’ clinical practices were involved in this study. By using questionnaires and case histories, the following information was collected: Age, gender, clinical diagnoses, and medications used. Results: In the current study, drugs were used that could potentially influence the effect of clopidogrel: Omeprazole, lipophilic statins, calcium channel blockers (CCB). There was a different use of the abovementioned drugs before and after the initiation of the clopidogrel therapy, e.g., 12 (15.0%) and 44 (55.0%) patients used proton pump inhibitors (PPI) before and after the clopidogrel therapy accordingly (P = 0.16; x² = 1.91). However, pantoprazole was recommended more often than other PPI. The use of the potential CYP3A4 inhibitors – lipophilic statins and CCB – was increased after the prescription of clopidogrel too. Concomitant use of statins (mainly atorvastatin) with clopidogrel was observed in 75 (93.8%) patients and the use of CCB (mainly amlodipine) – in 33 (41.3%) patients. Conclusion: In the primary health care practices, it is revealed that there is co-medication of clopidogrel with weak CYP3A4 inhibitors, such as lipophilic statins and amlodipine, and with the moderate CYP2C19 inhibitor – omeprazole. The latter co-medication is potentially harmful and it is very important to inform the first care professionals about the opportunity to change omeprazole to pantoprazole, which does not influence clopidogrel biotransformation.

Key words: Amlodipine, Atorvastatin, Clopidogrel, Drugedrug interaction, Omeprazole.