Antidepressant Identification — MRCPsych Paper B MCQ

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EasyMood DisordersAntidepressant IdentificationMRCPsych Paper B

A 30-year-old woman with depression is commenced on a new antidepressant. After 2 weeks, she reports increased appetite, weight gain and marked daytime sedation. The medication is classified as a noradrenergic and specific serotonergic antidepressant (NaSSA). Which antidepressant has she been prescribed?

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Correct answer: E — Mirtazapine

Mirtazapine is the correct answer. It is classified as a noradrenergic and specific serotonergic antidepressant (NaSSA). Presynaptic alpha-2 antagonism enhances noradrenergic and serotonergic neurotransmission, while 5-HT2 and 5-HT3 receptors are blocked. Its potent H1-receptor antagonism accounts for prominent sedation. Increased appetite and weight gain are also very common adverse effects and support the identification. Fluoxetine and sertraline are selective serotonin reuptake inhibitors, whereas venlafaxine and duloxetine are serotonin–noradrenaline reuptake inhibitors. Although other antidepressants can sometimes cause sedation or weight change, none of these distractors belongs to the NaSSA class.

Reference: Electronic Medicines Compendium. Mirtazapine 30 mg tablets: Summary of Product Characteristics, sections 4.8 and 5.1. Updated 8 September 2025. https://www.medicines.org.uk/emc/product/100083/smpc