Minor
Amitriptyline × Spironolactone
Tricyclic antidepressants (TCA)×Potassium-sparing diuretics (mineralocorticoid receptor antagonists)
Mechanism
No direct interaction. Additive orthostatic hypotension possible in older patients during hypovolaemia: spironolactone via diuresis, amitriptyline via α1-blockade.
Symptoms
Possible postural dizziness, fatigue. In older patients: fall risk.
Management
Begin amitriptyline at 10 mg at bedtime. In older patients, do not exceed 25 mg/day. Check standing/sitting BP at 1–2 weeks. With pronounced orthostatic hypotension, consider neuropathic-pain alternatives: gabapentin or pregabalin.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.