Alprazolam × Digoxin

Alprazolam raises blood digoxin levels, more often in patients over 65 (alprazolam labels in Spain and the US). The digoxin SmPC also lists alprazolam among drugs that increase serum digoxin. The documents do not say how large the rise is or what causes it: the FDA digoxin label places alprazolam in the group where the size of the effect is unclear. Digoxin has a narrow therapeutic index (FDA digoxin label), so even this rise can lead to toxicity.

Signs of digoxin toxicity: loss of appetite, nausea, vomiting, weakness, dizziness and visual changes, including yellow-green colour vision. Cardiac effects are rhythm and conduction disorders: ventricular premature beats, often as bigeminy, atrial tachycardia with block, atrioventricular block up to complete heart block, ventricular tachycardia (digoxin labels). Alprazolam itself causes drowsiness and muscle weakness, with a risk of falls in older people (alprazolam SmPC).

The combination is not prohibited, but it is managed by digoxin levels. The FDA alprazolam label requires measuring serum digoxin before alprazolam is started, then checking digoxin levels and signs of toxicity frequently and lowering the digoxin dose if needed. The FDA digoxin label requires the same approach whenever an interacting drug is started, changed or stopped. The Spanish alprazolam SmPC requires watching for signs of digoxin toxicity, especially in patients over 65. Patients on digoxin have serum electrolytes and creatinine checked periodically (digoxin SmPC). In older people alprazolam is started at a lower dose (alprazolam SmPC).