Passage transplacentaire des antirétroviraux

HIV-infected pregnant women should be offered antiretroviral (ARV) prophylaxis to prevent perinatal HIV transmission, as well as optimal therapies for their own health. Since the risk of vertical transmission decreases with lower maternal viral load, combination therapies exhibit a more pronounced antiviral efficacy than monotherapy in preventing such transmission. The investigation of placental transfer remains one of the cornerstones of pregnancy risk assessment. In vivo and ex vivo studies have established that maternal-fetal transfer of nucleoside analogs occurs rapidly suggesting a simple diffusion mechanism. The clearance index of HIV protease inhibitors (PI) at therapeutic levels is extremely low, with no accumulation in placental tissue. The low HIV PI placental transfer has been confirmed by in vivo studies and can be explained by their high plasma protein binding and liposolubility (except for indinavir whose placental transfer is high). In contrast with these findings, the nevirapine (non-nucleoside reverse transcriptase inhibitor) maternal/cord blood ratio averaged unity, indicating a high placental transfer. Finally some studies, physical-chemistry and pharmacokinetics properties regarding new drugs, show no enfuvirtide placental transfer, intermediate transfer of maraviroc and raltegravir and a high transfer of tenofovir and emtricitabine.