Impact of Antiretroviral Treatment on Pharmacokinetics and Pharmacodynamics of Thienopyridines in Healthy Volunteers and HIV Patients

HIV patients are at particular risk to develop cardiovascular disease (CVD) as they exhibit multiple risk factors by the nature of their pathology. In addition, the long term exposition to antiretroviral drugs has been associated to an increased risk for CVD. HIV patients can thus potentially receive antiplatelet therapy concomitantly with their antiretroviral treatment. Clopidogrel and prasugrel are thienopyridine antiplatelet agents indicated to prevent the recurrence of ischemic events after coronary arteries stenting. These pro-drugs are mainly bioactivated by cytochromes P450 (CYP) 3A and 2B6 for prasugrel and CYP2C19, CYP3A and CYP2B6 for clopidogrel. Ritonavir is commonly used to "boost" the bioavailability of other HIV drugs through inhibition of CYP3A4 as well as CYP2B6 and CYP2C9. This interaction could therefore reduce clopidogrel and prasugrel efficacy by reducing the formation of their active metabolites. The aim of the present study is to assess the potential drug-drug interaction between clopidogrel/prasugrel and ritonavir. Two groups of 12 male subjects will be constituted (12 HIV patients under ritonavir boosted therapy and 12 healthy volunteers) in a randomized cross-over clinical trial. All subjects will also be genotyped for the CYP2C19. The pharmacokinetics of clopidogrel active metabolite and prasugrel active metabolite will be assessed. Furthermore, the pharmacodynamic response will be evaluated by two gold standard platelet inhibition tests, namely VAsodilator-Stimulated Phosphoprotein Assay (VASP) and VerifyNow® assays. The primary endpoint of this study is to compare the pharmacodynamic response to clopidogrel and prasugrel in HIV patients to that of healthy volunteers.