MajorMacrolide antibiotic×HIV protease inhibitor / pharmacokinetic booster
Updated · Methodology
Mechanism
Dual CYP3A4 inhibition (clarithromycin + ritonavir). Plasma levels of both drugs rise, plus additive QT prolongation.
Symptoms
QT prolongation on ECG. Dizziness, syncope, palpitations. Severe cases: polymorphic ventricular tachycardia (torsades de pointes). Risk is higher with hypokalaemia and hypomagnesaemia.
Management
Avoid the combination. Alternative antibiotics without CYP3A4 inhibition: azithromycin or doxycycline. If clarithromycin is needed: ECG before start and every 3 days during therapy; do not increase clarithromycin dose.
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: Clarithromycin tablet (Solaris Pharma Corporation) – Prescribing Information section 7 (2017)– ; DailyMed setid 4d42821d-ce7a-7d64-e063-6294a90a0875
- AEMPS: Ficha técnica: Ritonavir (nº registro 81039), sección 4.5 (2025)– AEMPS, CIMA, nº registro 81039, sección 4.5
- AEMPS: Ficha técnica: Claritromicina (nº registro 75638), sección 4.5 (2025)– AEMPS, CIMA, nº registro 75638, sección 4.5