Psychiatric-Mental Health Nurse Practitioner Exam Medications 5 — Questions and Answers
Question 1: A patient with treatment-resistant depression is started on ketamine infusions. Which mechanism best explains its rapid antidepressant effect?
- Potent MAO-A inhibition leading to serotonin accumulation
- NMDA receptor antagonism followed by AMPA receptor upregulation and BDNF release (Correct answer)
- D2 receptor partial agonism stabilizing dopamine circuits
- Blockade of 5-HT3 receptors in the limbic system
Correct answer: NMDA receptor antagonism followed by AMPA receptor upregulation and BDNF release
Ketamine blocks NMDA receptors, causing a glutamate surge that activates AMPA receptors, releasing BDNF and promoting rapid synaptogenesis in the prefrontal cortex and hippocampus.
Question 2: Which long-acting injectable antipsychotic formulation has the longest dosing interval, allowing once-every-3-month administration?
- Paliperidone palmitate 1-month (Invega Sustenna)
- Aripiprazole monohydrate (Abilify Maintena)
- Paliperidone palmitate 3-month (Invega Trinza) (Correct answer)
- Risperidone microspheres (Risperdal Consta)
Correct answer: Paliperidone palmitate 3-month (Invega Trinza)
Paliperidone palmitate 3-month (Invega Trinza) is the only LAI antipsychotic approved for once-every-3-month dosing, improving adherence in stabilized patients.
Question 3: A patient with OCD is not responding to adequate SSRI trials. According to evidence-based guidelines, what is the next pharmacological step?
- Switch to an SNRI such as duloxetine
- Augment with a low-dose antipsychotic such as risperidone or aripiprazole (Correct answer)
- Add a benzodiazepine for anxiety reduction
- Switch to a TCA such as imipramine
Correct answer: Augment with a low-dose antipsychotic such as risperidone or aripiprazole
For SSRI-refractory OCD, augmentation with a low-dose D2-blocking antipsychotic (risperidone, aripiprazole, haloperidol) has the strongest evidence and is guideline-recommended.
Question 4: A patient with bipolar depression is prescribed quetiapine. At which dose range does quetiapine primarily exert antidepressant effects versus antipsychotic effects?
- Low doses (25-100 mg) for antipsychotic; high doses (400-800 mg) for antidepressant
- Low doses (50-150 mg) for antidepressant via H1/5-HT2 blockade; higher doses for antipsychotic via D2 blockade (Correct answer)
- Equal antidepressant and antipsychotic effects at all doses above 200 mg
- Antidepressant effects only occur at plasma levels above 800 ng/mL regardless of dose
Correct answer: Low doses (50-150 mg) for antidepressant via H1/5-HT2 blockade; higher doses for antipsychotic via D2 blockade
At lower doses, quetiapine preferentially blocks H1 and 5-HT2A receptors (contributing to antidepressant/sedating effects); D2 blockade (antipsychotic effect) predominates at higher doses.
Question 5: A patient on disulfiram for alcohol use disorder inadvertently uses an aftershave containing 70% ethanol. What reaction is expected and what is the mechanism?
- Mild euphoria due to disulfiram potentiating ethanol's CNS effects
- Flushing, nausea, tachycardia, and hypotension due to acetaldehyde accumulation from ALDH inhibition (Correct answer)
- Severe respiratory depression from combined CNS depressant effects
- No reaction because skin absorption of ethanol is insufficient to cause a disulfiram reaction
Correct answer: Flushing, nausea, tachycardia, and hypotension due to acetaldehyde accumulation from ALDH inhibition
Disulfiram inhibits aldehyde dehydrogenase (ALDH), causing acetaldehyde to accumulate when any ethanol source is absorbed, producing the aversive disulfiram-ethanol reaction even from topical exposures.
Question 6: Which of the following best describes the pharmacological profile of buspirone and its clinical implications?
- Buspirone is a GABA-A positive allosteric modulator with rapid onset useful for acute anxiety
- Buspirone is a 5-HT1A partial agonist with delayed onset (2-4 weeks) and no cross-tolerance with benzodiazepines (Correct answer)
- Buspirone blocks 5-HT3 receptors and has immediate anxiolytic effects similar to lorazepam
- Buspirone is a full D2 antagonist that treats anxiety through dopaminergic stabilization
Correct answer: Buspirone is a 5-HT1A partial agonist with delayed onset (2-4 weeks) and no cross-tolerance with benzodiazepines
Buspirone is a 5-HT1A partial agonist that requires 2-4 weeks for anxiolytic effect; it does not cause dependence or withdrawal but will not prevent benzodiazepine withdrawal in dependent patients.
Question 7: A PMHNP is evaluating a patient who takes lithium and is prescribed ibuprofen for arthritis pain. What pharmacokinetic concern must be addressed?
- NSAIDs induce renal CYP450 enzymes, accelerating lithium clearance and reducing efficacy
- NSAIDs reduce renal prostaglandin synthesis, decreasing GFR and increasing lithium reabsorption, risking toxicity (Correct answer)
- Ibuprofen displaces lithium from plasma protein binding sites, increasing free lithium levels acutely
- No clinically significant interaction exists between NSAIDs and lithium at standard arthritis doses
Correct answer: NSAIDs reduce renal prostaglandin synthesis, decreasing GFR and increasing lithium reabsorption, risking toxicity
NSAIDs inhibit prostaglandin-mediated renal efferent arteriolar dilation, reducing GFR and increasing lithium reabsorption in the proximal tubule, potentially raising lithium levels by 25-50%.
Psychiatric-Mental Health Nurse Practitioner Exam Medications 5
A patient with treatment-resistant depression is started on ketamine infusions.
Which mechanism best explains its rapid antidepressant effect?