Lavere koncentrationer af R- warfarin kan medføre reduceret antikoagulation, hvorfor det anbefales at monitorere antikoagulationsparametre ved samtidig indgift af warfarin og ritonavir doseret som et antiretroviralt stof eller som en farmakokinetisk forstærker.
Decreased R-warfarin levels may lead to reduced anticoagulation, therefore it is recommended that anticoagulation parameters are monitored when warfarin is co- administered with ritonavir dosed as an antiretroviral agent or as a pharmacokinetic enhancer.