Moderate
Amitriptyline × carvedilol
Tricyclic antidepressants (TCA)×Alpha and beta blocker (non-selective β + α1)
Mechanism
TCA blocks α1-adrenoceptors — additive orthostatic hypotension with carvedilol (α/β-blocker). Amitriptyline's additive bradycardia and QT effect intensify as heart rate drops with carvedilol.
Symptoms
Postural dizziness, syncope, fatigue. Older patients: fall and fracture risk.
Management
On starting the combination, begin amitriptyline at 10 mg at bedtime. In older patients, do not exceed 25 mg/day. Check standing/sitting BP, heart rate, and ECG at 2 weeks. For neuropathic pain, alternatives: gabapentin or pregabalin. For depression: sertraline or escitalopram (minimal cardiovascular effect).