CAADC Pharmacology and MAT 4 — Questions and Answers
Question 1: A patient on buprenorphine/naloxone reports that crushing and injecting the film precipitates immediate withdrawal. This is because naloxone in the sublingual formulation is:
- Absorbed sublingually at equal rates to buprenorphine
- Poorly bioavailable orally but active when injected intravenously (Correct answer)
- Metabolized by the liver before reaching systemic circulation
- Converted to an active metabolite only in the gut
Correct answer: Poorly bioavailable orally but active when injected intravenously
Naloxone has very low sublingual bioavailability but becomes fully active when injected IV, precipitating withdrawal in opioid-dependent individuals.
Question 2: Which pharmacological property of methadone makes it particularly effective for preventing opioid withdrawal symptoms throughout a 24-hour dosing interval?
- High first-pass metabolism
- Short half-life of 4–6 hours
- Long half-life of 24–36 hours or more (Correct answer)
- Rapid onset via sublingual absorption
Correct answer: Long half-life of 24–36 hours or more
Methadone's long half-life (24–36+ hours) allows once-daily dosing that suppresses withdrawal and craving throughout the day.
Question 3: A CAADC counselor is educating a patient about naltrexone extended-release injectable (Vivitrol). Which statement about its mechanism is accurate?
- It is a partial mu-opioid agonist that reduces craving by partial receptor activation
- It is a full opioid agonist that blocks euphoria through receptor saturation
- It is an opioid antagonist that blocks mu-opioid receptors and reduces reward from opioid use (Correct answer)
- It raises dopamine levels in the nucleus accumbens to reduce craving
Correct answer: It is an opioid antagonist that blocks mu-opioid receptors and reduces reward from opioid use
Naltrexone is a pure opioid antagonist; extended-release injectable formulation blocks mu-opioid receptors for approximately 30 days, eliminating opioid-induced euphoria.
Question 4: Acamprosate (Campral) is used as MAT for alcohol use disorder. Its primary proposed mechanism of action is:
- Blocking aldehyde dehydrogenase to create an aversive reaction to alcohol
- Modulating glutamate and GABA systems to reduce post-acute withdrawal symptoms (Correct answer)
- Stimulating serotonin reuptake inhibition to decrease alcohol craving
- Antagonizing dopamine D2 receptors in the mesolimbic pathway
Correct answer: Modulating glutamate and GABA systems to reduce post-acute withdrawal symptoms
Acamprosate is thought to restore the balance between glutamate excitation and GABA inhibition disrupted by chronic alcohol use, reducing post-acute withdrawal discomfort.
Question 5: When comparing buprenorphine's ceiling effect to full agonist opioids, the clinical implication for overdose risk is:
- Buprenorphine carries the same respiratory depression risk as heroin at equivalent doses
- Above a threshold dose, buprenorphine produces little additional respiratory depression, reducing overdose risk (Correct answer)
- Buprenorphine causes more respiratory depression than morphine due to slower receptor kinetics
- The ceiling effect applies only to analgesic effects, not respiratory depression
Correct answer: Above a threshold dose, buprenorphine produces little additional respiratory depression, reducing overdose risk
As a partial agonist, buprenorphine's respiratory depression plateaus at moderate doses, making fatal overdose from buprenorphine alone much less likely than with full agonists.
Question 6: A patient taking disulfiram (Antabuse) unknowingly consumes a cough syrup containing alcohol. The reaction they experience is due to accumulation of:
- Acetaldehyde, caused by inhibition of aldehyde dehydrogenase (Correct answer)
- Ethanol metabolites, caused by CYP2E1 enzyme induction
- Acetate, caused by inhibition of alcohol dehydrogenase
- Dopamine, caused by catechol-O-methyltransferase blockade
Correct answer: Acetaldehyde, caused by inhibition of aldehyde dehydrogenase
Disulfiram inhibits aldehyde dehydrogenase, causing acetaldehyde to accumulate after any alcohol ingestion, producing flushing, nausea, tachycardia, and hypotension.
Question 7: In the context of MAT, QTc prolongation is a documented concern most associated with which medication?
- Buprenorphine/naloxone
- Naltrexone extended-release
- Acamprosate
- Methadone (Correct answer)
Correct answer: Methadone
Methadone is associated with dose-dependent QTc prolongation and risk of torsades de pointes, requiring baseline and periodic ECG monitoring.
CAADC Pharmacology and MAT 4
A patient on buprenorphine/naloxone reports that crushing and injecting the film precipitates immediate withdrawal.
This is because naloxone in the sublingual formulation is: