Interaction between lopinavir/ritonavir and warfarin.
Drug interactions involving protease inhibitors are common. Protease inhibitors are well known inhibitors of the 3A4 isozyme of cytochrome P450. Select protease inhibitors, including co-formulated lopinavir/ritonavir, may induce glucuronidation or the activity of other CYP450 isozymes. We describe the case of a patient taking warfarin who experienced a significantly decreased international normalized ratio after the initiation of antiretroviral therapy that included lopinavir/ritonavir. We review the possible mechanisms of this interaction and the reported interactions between warfarin and other protease inhibitors.
Hughes
Christine A
CA
Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alta. chughes@pharmacy.ualberta.ca
Freitas
Andrea
A
Miedzinski
Lilly J
LJ
D000328:Adult; D019380:Anti-HIV Agents / Q000009:adverse effects*; D000925:Anticoagulants / Q000009:adverse effects*; D001777:Blood Coagulation / Q000187:drug effects; D004347:Drug Interactions; D017320:HIV Protease Inhibitors / Q000009:adverse effects*; D006801:Humans; D019934:International Normalized Ratio; D061466:Lopinavir; D008297:Male; D011744:Pyrimidinones / Q000009:adverse effects*; D019438:Ritonavir / Q000009:adverse effects*
D019380:Anti-HIV Agents; D000925:Anticoagulants; D017320:HIV Protease Inhibitors; D011744:Pyrimidinones; D061466:Lopinavir; D019438:Ritonavir
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