ASPPB Psychopharmacology 4 — Questions and Answers
Question 1: Which receptor mechanism explains why quetiapine at low doses (25–50 mg) is often used as a sleep aid?
- D2 receptor partial agonism promoting slow-wave sleep
- H1 histamine receptor antagonism causing sedation (Correct answer)
- GABA-A positive allosteric modulation
- 5-HT1A agonism reducing sleep onset latency
Correct answer: H1 histamine receptor antagonism causing sedation
Quetiapine's strong H1 histamine blockade at low doses produces sedation before appreciable D2 or 5-HT2A blockade occurs.
Question 2: A child with ADHD and a tic disorder is being considered for stimulant therapy. The current evidence-based recommendation is:
- Stimulants are absolutely contraindicated due to certain tic exacerbation
- Stimulants can be used; they do not consistently worsen tics and non-stimulants are an alternative (Correct answer)
- Only amphetamine salts are safe; methylphenidate always worsens tics
- Tics must fully resolve before any ADHD pharmacotherapy is initiated
Correct answer: Stimulants can be used; they do not consistently worsen tics and non-stimulants are an alternative
Current evidence shows stimulants do not reliably worsen tics in most children; alpha-2 agonists like guanfacine address both conditions.
Question 3: The mechanism by which disulfiram produces aversive effects when alcohol is consumed is:
- Blocking mu-opioid receptors to reduce reward
- Inhibiting aldehyde dehydrogenase, causing acetaldehyde accumulation (Correct answer)
- Competitively blocking alcohol dehydrogenase
- Inducing hepatic CYP2E1 to produce toxic alcohol metabolites
Correct answer: Inhibiting aldehyde dehydrogenase, causing acetaldehyde accumulation
Disulfiram inhibits ALDH2, preventing acetaldehyde oxidation; acetaldehyde accumulation causes flushing, nausea, and tachycardia.
Question 4: Which antipsychotic has the greatest risk of QTc prolongation and is associated with torsades de pointes?
- Aripiprazole
- Thioridazine (Correct answer)
- Risperidone
- Ziprasidone
Correct answer: Thioridazine
Thioridazine carries a black-box warning for QTc prolongation and torsades de pointes, leading to restricted use.
Question 5: Gabapentin's mechanism of action in treating neuropathic pain and anxiety involves:
- Blocking GABA reuptake transporters
- Binding to the alpha-2-delta subunit of voltage-gated calcium channels (Correct answer)
- Potentiating GABA-A receptor chloride conductance
- Inhibiting glutamate decarboxylase
Correct answer: Binding to the alpha-2-delta subunit of voltage-gated calcium channels
Gabapentin binds the alpha-2-delta subunit of voltage-gated Ca²⁺ channels, reducing presynaptic calcium influx and neurotransmitter release.
Question 6: A prescribing psychologist's patient develops fever, muscle rigidity, altered consciousness, and autonomic instability two days after starting haloperidol. The priority intervention is:
- Administer lorazepam and continue haloperidol at lower dose
- Discontinue the antipsychotic and provide supportive care; consider dantrolene or bromocriptine (Correct answer)
- Add benztropine to counteract extrapyramidal symptoms
- Switch to a second-generation antipsychotic immediately
Correct answer: Discontinue the antipsychotic and provide supportive care; consider dantrolene or bromocriptine
This presentation is Neuroleptic Malignant Syndrome; immediate antipsychotic discontinuation and supportive care are essential, with dantrolene or bromocriptine for severe cases.
Question 7: Which of the following correctly describes the concept of therapeutic window in pharmacology?
- The time from administration to peak plasma concentration
- The range of plasma concentrations producing efficacy without toxicity (Correct answer)
- The interval between doses that maintains steady state
- The ratio of protein-bound to free drug in plasma
Correct answer: The range of plasma concentrations producing efficacy without toxicity
Therapeutic window refers to the concentration range above which toxicity occurs and below which efficacy is lost; lithium has a notably narrow window.
ASPPB Psychopharmacology 4
Which receptor mechanism explains why quetiapine at low doses (25–50 mg) is often used as a sleep aid?