Major
Budesonide × Ketoconazole
Inhaled corticosteroids (ICS)×Systemic antimycotics. Imidazole derivatives
Mechanism
Ketoconazole strongly blocks CYP3A4 – the main budesonide metabolic route. Systemic budesonide exposure (oral or inhaled) rises 6- to 12-fold. High Cushing's syndrome risk with prolonged combination.
Symptoms
Moon face, central obesity, abdominal striae, hypertension, hyperglycaemia. With prolonged combination and abrupt withdrawal: adrenal insufficiency risk.
Management
The combination is not prescribed. Alternative antifungals: terbinafine for dermatophytosis or echinocandins for systemic mycoses. Alternative inhaled corticosteroid: fluticasone/mometasone (less CYP3A4-dependent).