Neuro-pharmacology Practice Questions
20 free Neuro-pharmacology practice questions for the USMLE Step 1. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
A patient with schizophrenia begins haloperidol therapy. Within days, he develops severe muscle stiffness and neck rigidity. Which adverse effect is most likely responsible?
- A Tardive dyskinesia
- B Acute dystonia
- C Akathisia
- D Neuroleptic malignant syndrome
Correct answer: Acute dystonia
Acute dystonia is an early extrapyramidal effect of antipsychotics, presenting with sudden muscle spasms and rigidity.
A patient taking lithium for bipolar disorder begins experiencing tremor and confusion after starting hydrochlorothiazide. What is the most likely mechanism?
- A Increased lithium excretion
- B Reduced lithium absorption
- C Decreased lithium clearance
- D Lithium receptor antagonism
Correct answer: Decreased lithium clearance
Thiazides decrease sodium levels, increasing lithium reabsorption in the kidneys and leading to toxicity.
A woman is prescribed fluoxetine for major depression. She is also taking a MAO inhibitor. What is the major risk of combining these medications?
- A Sedation
- B Serotonin syndrome
- C Neuroleptic malignant syndrome
- D Tardive dyskinesia
Correct answer: Serotonin syndrome
Combining SSRIs with MAOIs causes excess serotonin, leading to life-threatening serotonin syndrome.
A patient with generalized anxiety disorder is started on buspirone. Which characteristic differentiates it from benzodiazepines?
- A Immediate anxiolytic onset
- B High risk of dependence
- C 5-HT1A partial agonism
- D Causes marked sedation
Correct answer: 5-HT1A partial agonism
Buspirone is a 5-HT1A partial agonist without sedative or dependence risks, but with delayed onset.
A patient taking levodopa for Parkinson disease develops hallucinations. Which drug can reduce this effect without worsening motor symptoms?
- A Haloperidol
- B Benztropine
- C Clozapine
- D Propranolol
Correct answer: Clozapine
Clozapine treats psychosis in Parkinson patients with minimal extrapyramidal symptoms.
A man with chronic pain is started on amitriptyline. What is the most likely adverse effect?
- A Urinary retention
- B Bradycardia
- C Hypoglycemia
- D Increased seizure threshold
Correct answer: Urinary retention
TCAs have anticholinergic effects, including urinary retention, dry mouth, and constipation.
A patient with epilepsy begins valproate therapy. Which serious adverse effect requires monitoring?
- A Renal failure
- B Hepatotoxicity
- C Hypothyroidism
- D Cardiomyopathy
Correct answer: Hepatotoxicity
Valproate can cause fatal hepatotoxicity, particularly in children, requiring liver function monitoring.
A patient taking phenytoin presents with gingival hyperplasia. What mechanism explains this adverse effect?
- A Reduced bone density
- B Increased fibroblast growth
- C Direct mucosal irritation
- D Immune-mediated inflammation
Correct answer: Increased fibroblast growth
Phenytoin stimulates fibroblast growth and collagen deposition, causing gingival enlargement.
A patient with Alzheimer disease is started on donepezil. What is its mechanism?
- A Glutamate receptor antagonist
- B Dopamine reuptake inhibitor
- C Acetylcholinesterase inhibitor
- D Tau protein stabilizer
Correct answer: Acetylcholinesterase inhibitor
Donepezil increases acetylcholine levels by inhibiting its breakdown, improving cognitive symptoms.
A patient receiving morphine develops respiratory depression. Which drug reverses this effect?
- A Buprenorphine
- B Naloxone
- C Methadone
- D Loperamide
Correct answer: Naloxone
Naloxone is a fast-acting opioid antagonist used for opioid overdose reversal.
A patient experiences acute anxiety during a flight and is prescribed medication with rapid onset. Which drug is appropriate?
- A Buspirone
- B Fluoxetine
- C Lorazepam
- D Propranolol
Correct answer: Lorazepam
Lorazepam, a benzodiazepine, acts rapidly and is effective for situational anxiety.
A patient with migraines is prescribed sumatriptan. What is its mechanism of action?
- A β-adrenergic receptor blockade
- B 5-HT1B/1D receptor agonism
- C Calcium channel blockade
- D D2 receptor antagonism
Correct answer: 5-HT1B/1D receptor agonism
Sumatriptan activates 5-HT1B/1D receptors, causing vasoconstriction and reducing trigeminal pain signaling.
A patient begins carbamazepine for trigeminal neuralgia. Which lab value should be monitored?
- A Hemoglobin level
- B Serum creatinine
- C Leukocyte count
- D Serum calcium
Correct answer: Leukocyte count
Carbamazepine may cause agranulocytosis and requires periodic CBC monitoring.
A woman taking topiramate for seizures develops kidney stones. What mechanism contributes to this?
- A Increased uric acid reabsorption
- B Carbonic anhydrase inhibition
- C Hyperparathyroidism
- D Oxalate accumulation
Correct answer: Carbonic anhydrase inhibition
Topiramate inhibits carbonic anhydrase, leading to metabolic acidosis and increased risk of kidney stones.
A patient taking MAO inhibitors experiences hypertension after eating cheese and wine. What causes this reaction?
- A Excess histamine release
- B Sudden dopamine release
- C Tyramine catecholamine surge
- D Relative serotonin deficiency
Correct answer: Tyramine catecholamine surge
Tyramine promotes catecholamine release, and MAO inhibition prevents its metabolism, causing hypertensive crisis.
A man with Parkinson disease is prescribed entacapone. What is its therapeutic mechanism?
- A Dopamine receptor agonism
- B Inhibition of MAO-B
- C Inhibition of COMT
- D Anticholinergic activity
Correct answer: Inhibition of COMT
Entacapone inhibits COMT, prolonging levodopa activity and improving motor symptoms.
A patient with status epilepticus is treated with IV benzodiazepines. What receptor is primarily targeted?
- A GABA-A receptor
- B GABA-B receptor
- C NMDA receptor
- D AMPA receptor
Correct answer: GABA-A receptor
Benzodiazepines enhance GABA-A receptor activity, increasing chloride influx and neuronal inhibition.
A patient treated with antipsychotics develops hyperprolactinemia. Which drug is most likely responsible?
- A Clozapine
- B Aripiprazole
- C Olanzapine
- D Risperidone
Correct answer: Risperidone
Risperidone strongly blocks D2 receptors in the tuberoinfundibular pathway, increasing prolactin levels.
A man with opioid addiction begins methadone maintenance therapy. Which property makes methadone effective?
- A Short half-life
- B Partial agonism
- C Long half-life
- D Weak receptor affinity
Correct answer: Long half-life
Methadone’s long half-life prevents withdrawal and stabilizes opioid levels.
A patient taking bupropion for depression asks why it does not cause sexual dysfunction like SSRIs. What is its mechanism?
- A Serotonin 5-HT1A partial agonism
- B Norepinephrine-dopamine reuptake inhibition
- C Presynaptic α2-receptor antagonism
- D Monoamine oxidase (MAO) inhibition
Correct answer: Norepinephrine-dopamine reuptake inhibition
Bupropion increases norepinephrine and dopamine without significant serotonergic activity, reducing risk of sexual side effects.