MajorInhaled corticosteroids (ICS)×HIV protease inhibitor / pharmacokinetic booster
Updated · Methodology
Mechanism
Ritonavir is the most potent CYP3A4 inhibitor available. Systemic budesonide exposure (inhaled or oral) rises 8- to 10-fold. High risk of iatrogenic Cushing's syndrome, especially during long-term inhaled therapy for asthma or COPD.
Symptoms
Moon face, central obesity, abdominal striae, hypertension, hyperglycaemia. With prolonged combination and abrupt withdrawal: adrenal insufficiency risk.
Management
Avoid the combination. Alternative inhaled corticosteroid: beclomethasone (less CYP3A4-dependent) or short-acting β2-agonists with inhaled anticholinergics. If replacement is impossible: minimum effective budesonide dose with glucose and blood pressure monitoring.
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
- EMA: Huperzine A is not authorised as a medicinal product in the EU (2024)– EMA – no centralised authorisation for huperzine A
- AEMPS: Ficha técnica: Ritonavir (nº registro 81039), sección 4.5 (2025)– AEMPS, CIMA, nº registro 81039, sección 4.5