MajorAntiplatelet agents – P2Y12 receptor inhibitors×HIV protease inhibitor / pharmacokinetic booster
Updated · Methodology
Mechanism
Ritonavir blocks CYP3A4 and CYP2C19, through which clopidogrel becomes its active metabolite. The active metabolite is not formed – antiplatelet effect is lost. Ritonavir also induces glucuronidation, further reducing clopidogrel activity.
Symptoms
The patient feels no symptoms – the weakened antiplatelet effect is silent. In patients with a coronary stent or after acute coronary syndrome: risk of recurrent myocardial infarction, stent thrombosis, and ischaemic stroke.
Management
Avoid the combination. Alternative antiplatelet: ticagrelor (no CYP2C19 activation needed). If ticagrelor is impossible: prasugrel (requires activation but via a different route) with caution.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- FDA: Norvir (ritonavir) prescribing information contraindications (2018)– ; DailyMed setid 2849298e-de6e-47bb-8194-56e075b33fc3
- AEMPS: Ficha técnica: Clopidogrel (nº registro 71676), sección 4.5 (2024)– AEMPS, CIMA, nº registro 71676, revisión 02/2024, sección 4.5