Clopidogrel and the possibility of drug-drug 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 drug-drug interaction with CYP2C19 and CYP3A4 enzyme inhibitors. The main goal of this descriptive study was to assess the prevalence of cases of clopidogrel-drug 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 above-mentioned 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; χ (2) = 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.