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Clomipramine for OCD — MRCPsych Paper B MCQ

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ModerateAnxiety & Stress-Related DisordersClomipramine for OCDMRCPsych Paper B

A 40-year-old man with obsessive-compulsive disorder has had an inadequate response to CBT including exposure and response prevention and to adequate SSRI treatment. Clomipramine is being considered. Which pharmacological property best explains clomipramine's distinctive anti-obsessional role among tricyclic antidepressants?

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Correct answer: A — Preferential inhibition of serotonin reuptake

Clomipramine is a tricyclic antidepressant that inhibits both serotonin and noradrenaline reuptake, but its inhibition of serotonin reuptake is the more important pharmacological activity. This prominent serotonergic action is associated with its established anti-obsessional efficacy and helps explain why NICE treats clomipramine as an exception to other TCAs in OCD. It is not a selective noradrenaline reuptake inhibitor. Muscarinic, H1 and alpha1 antagonism contribute adverse effects such as anticholinergic symptoms, sedation and postural hypotension rather than the specific anti-obsessional effect. Clomipramine should not simply be described as more effective than SSRIs, as direct comparisons do not consistently establish superiority. Baseline ECG assessment is specifically recommended by NICE when there is significant cardiovascular risk, rather than being universally required for every adult.

Reference: Electronic Medicines Compendium. Clomipramine 10 mg Capsules, Hard, Summary of Product Characteristics, section 5.1 Pharmacodynamic properties. Updated 17 August 2026. https://www.medicines.org.uk/emc/product/2552/smpc