Expansion
SSRIs, SNRIs, tricyclics and MAO inhibitors
Expansion
- SSRIs (fluoxetine, sertraline, citalopram): first line. Nausea, sexual dysfunction, hyponatraemia, GI bleeding especially with NSAIDs, QT prolongation with citalopram. Fluoxetine has the longest half-life, useful for poor adherence
- SNRIs (venlafaxine, duloxetine): also used in neuropathic pain; can raise blood pressure
- Tricyclics (amitriptyline, nortriptyline): effective but antimuscarinic (dry mouth, retention, blurred vision, confusion), postural hypotension, and dangerous in overdose through sodium channel blockade causing broad complex arrhythmia and seizures, treated with sodium bicarbonate
- Mirtazapine: sedating with weight gain, useful where insomnia and poor appetite are prominent
- MAO inhibitors: rarely used; tyramine reaction with cheese and cured meats causing hypertensive crisis
Serotonin syndrome is the key emergency: altered mental state, autonomic instability and neuromuscular excitability with clonus and hyperreflexia, developing within hours. Precipitated by combining serotonergic drugs including tramadol, linezolid, triptans and St John’s wort. It is distinguished from neuroleptic malignant syndrome, which develops over days with rigidity and hyporeflexia.
All antidepressants take 2 to 4 weeks to work and should be tapered on stopping.