CARN Pharmacology of Addictive Substances 3 — Questions and Answers
Question 1: Which pharmacokinetic property of fentanyl makes transdermal patches particularly dangerous when misused (e.g., chewed or injected with extracted gel)?
- Fentanyl has low protein binding allowing rapid systemic distribution
- Fentanyl patches contain a reservoir of drug designed for 72-hour release that can be rapidly absorbed if misused (Correct answer)
- Fentanyl undergoes extensive first-pass metabolism when swallowed
- Fentanyl has a very long half-life of 48 hours
Correct answer: Fentanyl patches contain a reservoir of drug designed for 72-hour release that can be rapidly absorbed if misused
Transdermal fentanyl patches contain 72-hour drug reservoirs; chewing or extracting the gel delivers the full dose rapidly, causing fatal overdose.
Question 2: Acamprosate reduces alcohol craving primarily by which mechanism?
- Blocking dopamine D2 receptors in the reward pathway
- Modulating NMDA glutamate receptors and GABA activity to restore neurochemical balance (Correct answer)
- Inhibiting alcohol dehydrogenase to slow alcohol metabolism
- Enhancing serotonin reuptake in the prefrontal cortex
Correct answer: Modulating NMDA glutamate receptors and GABA activity to restore neurochemical balance
Acamprosate restores balance between inhibitory GABA and excitatory glutamate systems disrupted by chronic alcohol use, reducing the hyperexcitability driving craving.
Question 3: A nurse is counseling a patient about disulfiram therapy. Which dietary item should the patient be warned to avoid due to its alcohol content?
- Orange juice
- Mouthwash containing ethanol (Correct answer)
- Decaffeinated coffee
- Non-fat milk
Correct answer: Mouthwash containing ethanol
Mouthwash often contains significant ethanol; even topical or small oral exposure can trigger a disulfiram-ethanol reaction (flushing, tachycardia, nausea).
Question 4: Cannabis produces its psychoactive effects primarily by acting on which receptor system?
- CB1 cannabinoid receptors in the CNS (Correct answer)
- TRPV1 vanilloid receptors in the periphery
- Alpha-2 adrenergic receptors in the locus coeruleus
- 5-HT2A serotonin receptors in the cortex
Correct answer: CB1 cannabinoid receptors in the CNS
THC acts as a partial agonist at CB1 receptors in the CNS, producing psychoactive effects including euphoria, altered perception, and impaired memory.
Question 5: Methadone's utility in opioid use disorder is partly due to its long half-life. What is the approximate half-life of methadone?
- 2–4 hours
- 8–12 hours
- 24–36 hours (Correct answer)
- 5–7 days
Correct answer: 24–36 hours
Methadone's half-life of 24–36 hours (sometimes up to 59 hours) allows once-daily dosing and prevents withdrawal, supporting medication adherence.
Question 6: Which illicit opioid is frequently involved in overdose deaths due to its extremely high potency relative to morphine?
- Codeine
- Tramadol
- Illicitly manufactured fentanyl (IMF) (Correct answer)
- Buprenorphine
Correct answer: Illicitly manufactured fentanyl (IMF)
Illicitly manufactured fentanyl is approximately 100 times more potent than morphine, making even microgram dosing errors fatal.
Question 7: When administering naloxone to a patient with suspected opioid overdose, which finding would suggest the need for repeated dosing?
- Blood pressure normalizes within 2 minutes
- Respiratory rate increases to 16 breaths/min briefly then decreases again (Correct answer)
- Pupils dilate symmetrically
- Patient becomes agitated and combative
Correct answer: Respiratory rate increases to 16 breaths/min briefly then decreases again
Naloxone's half-life (~60–90 min) is shorter than many opioids, so the opioid effect can return, requiring repeat dosing or infusion for long-acting opioids.
CARN Pharmacology of Addictive Substances 3
Which pharmacokinetic property of fentanyl makes transdermal patches particularly dangerous when misused (e.g., chewed or injected with extracted gel)?