Psychopharmacology

Psychopharmacology is the highest-weighted domain on the ANCC PMHNP certification exam, accounting for roughly 25% of questions. The exam tests your ability to select appropriate medications based on clinical presentation, understand mechanisms of action at the receptor level, and anticipate drug-drug interactions through the cytochrome P450 system.

Expect questions on first-line agents for major depressive disorder, bipolar disorder, schizophrenia, and anxiety disorders. The exam emphasizes practical prescribing decisions: when to augment vs. switch, how to manage side effects, and which labs to monitor. CYP450 interactions — especially 2D6, 1A2, and 3A4 — appear frequently.

You will also be tested on controlled substance regulations, black box warnings, pregnancy risk categories, and medication-specific monitoring requirements (lithium levels, clozapine ANC, valproate hepatic panels). Know the clinical significance of pharmacokinetic concepts like half-life, steady state, and first-pass metabolism.

• ✕Confusing CYP450 inhibitors with inducers — for example, fluvoxamine is a potent CYP1A2 inhibitor, while carbamazepine is a CYP3A4 inducer. Mixing these up leads to wrong answers on drug interaction questions.
• ✕Treating all SSRIs as interchangeable. The exam tests specific differences: paroxetine's anticholinergic load, fluoxetine's long half-life, fluvoxamine's unique CYP profile, and sertraline's relative safety in pregnancy and breastfeeding.
• ✕Not knowing dose-dependent receptor binding profiles. Quetiapine at low doses acts primarily as an antihistamine (sedation), while higher doses engage dopamine D2 receptors (antipsychotic effect). Venlafaxine is functionally an SSRI below 150mg and only becomes an SNRI at higher doses.
• ✕Forgetting monitoring timelines — lithium levels are drawn 12 hours post-dose at steady state (5 days), clozapine requires weekly ANC for the first 6 months, and lamotrigine must be titrated slowly to reduce Stevens-Johnson risk.
• ✕Overlooking contraindications tied to comorbidities: bupropion in eating disorders or seizure history, stimulants with significant cardiac disease, MAOIs with almost everything.