Neuropsychiatric and Pain Management Pharmacotherapy
What the exam tests
Neuropsychiatric and pain questions test diagnosis-linked drug selection, monitoring for toxicity, interactions and opioid safety. Expect questions on depression, bipolar disorder, schizophrenia, epilepsy, migraine and acute or chronic pain.
Core rules
- Major depression: SSRIs or SNRIs are first-line; allow 4–6 weeks at an adequate dose. Screen for bipolar disorder before starting an antidepressant.
- Serotonin syndrome: clonus, hyperreflexia, agitation, hyperthermia; stop serotonergic drugs and give supportive care. Avoid combining an MAOI with an SSRI; allow a two-week washout (five weeks for fluoxetine).
- Lithium: monitor levels, renal function, thyroid and calcium; toxicity risk rises with dehydration, NSAIDs, thiazides and ACE inhibitors.
- Antipsychotics: monitor weight, glucose, lipids and prolactin; clozapine requires white-cell monitoring because of agranulocytosis.
- Pain: use the analgesic ladder, reassess, and prescribe naloxone where opioid overdose risk is high. Opioid conversion must account for incomplete cross-tolerance.
Worked example
A patient on lithium 900 mg daily develops vomiting, tremor and confusion. Lithium level is 2.1 mmol/L. Stop lithium, give IV fluids, check renal function and ECG, and consider hemodialysis if severe toxicity or renal failure. Avoid NSAIDs and thiazides during recovery.
Traps
Continuing an SSRI in suspected serotonin syndrome; missing lithium toxicity behind gastroenteritis; using carbamazepine without checking interactions; starting an antidepressant in bipolar depression without a mood stabilizer; using pethidine for pain in a patient on an MAOI.