Antidepressants treat major depression, anxiety disorders (generalised, social, panic), OCD and neuropathic pain. SSRIs (fluoxetine, sertraline, paroxetine, escitalopram, citalopram) are first-line — they selectively inhibit serotonin reuptake, with better safety profile than tricyclics. SNRIs (venlafaxine, duloxetine) inhibit serotonin and noradrenaline reuptake — useful in treatment-resistant depression and neuropathic pain. Tricyclics (amitriptyline) non-selectively inhibit serotonin and noradrenaline reuptake — effective but with more side effects (anticholinergic, cardiotoxicity in overdose). Mirtazapine (NaSSA — 5-HT2A/5-HT3/α2 antagonist) has a sedative profile and is useful in patients with insomnia and weight loss. Therapeutic onset is typically 2-4 weeks. Discontinuation should be gradual to avoid withdrawal syndrome. (Sources: DailyMed/FDA, EMC-UK/MHRA, NICE CG90)
