Amiodarone × Budesonide

Budesonide is broken down mainly by the CYP3A4 enzyme, and amiodarone and its metabolite inhibit this enzyme (amiodarone SmPC). Budesonide levels may rise, and with them the risk of systemic corticosteroid effects; these effects are less likely with inhaled than with oral budesonide (inhaled budesonide SmPC). A second mechanism involves systemic corticosteroids: they can lower potassium, and low potassium during amiodarone treatment raises the risk of torsades de pointes (amiodarone SmPC). Amiodarone is eliminated slowly, so interactions can occur for several months after it is stopped (amiodarone SmPC).

With long-term treatment: rounded face, weight gain with fat redistribution, thin skin, acne, muscle weakness, mood changes, raised blood glucose. If potassium falls during amiodarone treatment: palpitations, fainting, QT prolongation on the electrocardiogram (ECG) and, in severe cases, torsades de pointes.

Oral budesonide should not be combined with CYP3A4 inhibitors unless the benefit outweighs the higher risk of systemic corticosteroid effects; if the combination is used, monitor the patient for these effects (oral budesonide SmPC). Amiodarone inhibits CYP3A4 (amiodarone SmPC), so this applies to it. The inhaled budesonide SmPC says to avoid strong CYP3A inhibitors and gives itraconazole, ketoconazole, human immunodeficiency virus (HIV) protease inhibitors and cobicistat-containing products as examples; amiodarone is not among them. With a 1–2 week course the interaction with inhaled budesonide is of limited relevance; in long-term treatment take it into account and watch for systemic effects (inhaled budesonide SmPC). Use amiodarone with caution alongside systemic corticosteroids: prevent and correct low potassium, monitor the QT interval, and do not give antiarrhythmic drugs if torsades de pointes occurs (amiodarone SmPC). Interactions with amiodarone can occur for several months after it is stopped (amiodarone SmPC).