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TRD Augmentation — MRCPsych Paper B MCQ

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HardMood DisordersTRD AugmentationMRCPsych Paper B

A 45-year-old woman with recurrent unipolar major depression has had no meaningful response despite adherence to three antidepressants prescribed at therapeutic doses for adequate durations. Bipolar disorder, psychotic depression, substance misuse and relevant physical causes have been excluded. She currently takes venlafaxine 225 mg daily and is reviewed in a specialist service for pharmacological augmentation. She prefers an established conventional augmenter for which a UK medicinal product has a licensed indication in recurrent depressive episodes when other antidepressants have been unsuccessful, rather than an off-label strategy. Which option best meets this criterion?

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Correct answer: B — Lithium augmentation

Lithium augmentation is correct. NICE includes combining an antidepressant with lithium among specialist further-line treatments, and a UK lithium preparation is licensed for recurrent depressive episodes when other antidepressants have been unsuccessful. Liothyronine is also a possible NICE-listed augmentation strategy, making it the strongest distractor, but its use for depression is off-label and its evidence is less extensive and heterogeneous. Buspirone and pindolol have not demonstrated consistent efficacy in treatment-resistant depression and are not NICE-listed augmentation options. Ordinary folic acid is not an established TRD augmenter and should not be conflated with research concerning L-methylfolate. Before lithium, assess renal and thyroid function, calcium, weight, pregnancy considerations and interactions; subsequently monitor 12-hour plasma lithium concentrations.

Reference: Priadel 400 mg prolonged-release tablets, Summary of Product Characteristics, sections 4.1–4.2, updated 8 April 2025. https://www.medicines.org.uk/emc/product/13163/smpc