Biological Treatments and Psychopharmacology: Mechanisms and Monitoring
Core concepts
Know the receptor pharmacology and adverse-effect profiles of major drug classes: SSRIs (serotonergic; GI upset, hyponatraemia, sexual dysfunction, serotonin syndrome), SNRIs (noradrenergic; hypertension), TCAs (anticholinergic and cardiotoxic in overdose), MAOIs (tyramine reaction, hypertensive crisis), antipsychotics (D2 blockade; extrapyramidal effects, hyperprolactinaemia, metabolic syndrome, QT prolongation, and the specific risk of agranulocytosis with clozapine), mood stabilisers (lithium: narrow therapeutic index, renal and thyroid effects, toxicity; valproate: teratogenicity; lamotrigine: rash), and benzodiazepines (tolerance, dependence, respiratory depression).
Traps
Questions test monitoring requirements and contraindications rather than dosing minutiae. Remember lithium levels, renal and thyroid function, calcium, and ECG; clozapine requires regular full blood counts. Avoid assuming that a drug's class guarantees a shared adverse-effect profile. ECT is indicated for severe, life-threatening depression, catatonia, and treatment-resistant illness; memory effects are usually transient.
Worked example
A patient on lithium develops tremor, vomiting, and ataxia. The rule of thumb: check the level, renal function, and hydration; consider interacting drugs (NSAIDs, thiazides, ACE inhibitors) that reduce lithium clearance. Toxicity is managed by stopping the drug, correcting volume status, and considering dialysis in severe cases.
Key points for revision
Link each drug to its receptor target and its monitoring requirement.