Risk factors for adverse drug reactions associated with clopidogrel therapy.

This study aimed to investigate the possible influence of genetic and non-genetic factors on the incidence of clopidogrel adverse drug reactions (ADRs) in cardiology patients, including the most important alleles, namely *2 and *17, as well as compliance, dose, drug interactions, and clinical factors. A total of 102 clopidogrel-treated adult Caucasian patients hospitalized at the Cardiology Department of the Clinical Center of Montenegro were enrolled in the study. Data on clinical outcomes of interest were obtained by intensive monitoring ADRs during hospitalization and one year after hospital discharge. Genotyping for *2 and *17 was conducted using the real-time polymerase chain reaction method. ADRs were characterized using the Rawlins and Thompson classification and the World Health Organization criteria. Causality was assessed using the Naranjo probability scale. ADRs to clopidogrel were observed in 9 of 102 patients (8.8%). The observed frequencies of *2 and *17 were 13.2 and 25.5%, respectively. Our study, which is the first to report the frequency of polymorphism in the Montenegrin population, as well as to link the pharmacovigilance of clopidogrel with gene variability, shows that the incidence of ADRs of clopidogrel in cardiac patients is high and depends on polymorphisms, comedication/drug interactions, and gastrointestinal comorbidity.