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Amitriptyline Dosing — MRCPsych Paper B MCQ

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EasyLiaison PsychiatryAmitriptyline DosingMRCPsych Paper B

A 45-year-old patient with neuropathic pain is prescribed amitriptyline 25 mg at night, titrated according to response to a maximum of 75 mg daily. A colleague notes that higher doses may be used when amitriptyline is prescribed for major depressive disorder. Which statement best accounts for this difference?

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Reveal the answer and explanation

Correct answer: C — Its analgesic action is distinct from its antidepressant action and usually uses lower doses

Explanation lettering: E = shown as B · B = shown as C · C = shown as E

B is correct. Amitriptyline has an analgesic action that is not dependent on treating depression. Its analgesic effects involve modulation of noradrenergic pain pathways and ion channels, including sodium and NMDA channels. For neuropathic pain, the usual initial dose is 10–25 mg at night and the recommended range is 25–75 mg daily, titrated to benefit and tolerability. For major depressive disorder, the usual initial adult dose is 50 mg daily and it may be increased to 150 mg daily. The dose ranges are therefore not identical, and analgesic doses should not routinely be increased to 150 mg. Both analgesic and antidepressant benefits may take 2–4 weeks, so immediate analgesia is not the explanation.

Reference: Electronic Medicines Compendium. Amitriptyline Hydrochloride 10 mg Film-Coated Tablets: Summary of Product Characteristics, sections 4.2 and 5.1. Updated 17 November 2025. https://www.medicines.org.uk/emc/product/13493/smpc