Moderate
Azithromycin × Ketoconazole
Macrolides×Systemic antimycotics. Imidazole derivatives
Mechanism
Additive QT prolongation.
Symptoms
QT prolongation on ECG. Dizziness, syncope, palpitations. Rarely: polymorphic ventricular tachycardia (torsades de pointes). Risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, and ischaemic heart disease.
Management
Avoid the combination. Alternative antifungals: terbinafine for dermatophytosis or echinocandins for systemic mycoses. Alternative antibiotics: a cephalosporin or doxycycline (no QT effect).