Amiodarone × Dexamethasone

Dexamethasone is a weak CYP3A4 inducer and may slightly reduce amiodarone levels in long-term therapy. The additive QT effect is minimal but persists in predisposed patients.

Short dexamethasone pulses usually cause no 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.

For short dexamethasone courses (3–7 days), no specific adjustment needed. For long-term therapy, check ECG every 3 months. In atrial fibrillation with uncontrolled rate, consider raising amiodarone by 50–100 mg/day.