ModerateTricyclic antidepressants (TCA)×Selective β1-adrenoceptor blockers
Updated · Methodology
Mechanism
Amitriptyline is a CYP2D6 substrate, as is metoprolol. Enzyme competition raises both drug levels. Plus additive anticholinergic effect on the heart (bradycardia, PR prolongation).
Symptoms
Bradycardia (heart rate below 50/min), dizziness, syncope. ECG: PR prolongation. Older patients: delirium and fall risk.
Management
In older patients, check pulse and ECG 1–2 weeks after starting amitriptyline. Alternative beta-blocker without CYP2D6 dependence: bisoprolol or carvedilol. For neuropathic pain, alternative: 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.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- FDA: Amitriptyline HCl tablets prescribing information (2014)– ; DailyMed setid 4e520c63-1cf6-40f6-a51c-3f9b0e181342
- AEMPS: Ficha técnica: Amitriptilina (nº registro 89862), sección 4.5 (2026)– AEMPS, CIMA, nº registro 89862, revisión 05/2026, sección 4.5