Chemical Dependency Counselor License Exam Pharmacology of Substance Use 2 — Questions and Answers
Question 1: Which neurotransmitter system is primarily responsible for the euphoric reinforcement produced by opioids?
- Serotonin in the raphe nuclei
- Dopamine in the mesolimbic pathway (Correct answer)
- GABA in the cerebellum
- Acetylcholine in the basal ganglia
Correct answer: Dopamine in the mesolimbic pathway
Opioids activate mu-receptors on GABA interneurons, disinhibiting dopaminergic neurons in the ventral tegmental area and flooding the nucleus accumbens with dopamine.
Question 2: A client taking methadone for OUD is prescribed erythromycin for a bacterial infection. The primary pharmacological concern is:
- Erythromycin blocking methadone absorption in the gut
- QTc interval prolongation due to combined CYP3A4 inhibition (Correct answer)
- Increased methadone clearance causing withdrawal
- Erythromycin cross-reacting with opioid receptors
Correct answer: QTc interval prolongation due to combined CYP3A4 inhibition
Both methadone and erythromycin prolong the QT interval; erythromycin also inhibits CYP3A4, raising methadone plasma levels and amplifying cardiac risk.
Question 3: Which benzodiazepine property makes it most likely to produce severe withdrawal seizures upon abrupt discontinuation?
- High lipid solubility
- Long elimination half-life
- Short half-life with high potency (Correct answer)
- Selective GABA-A alpha-1 binding
Correct answer: Short half-life with high potency
Short-acting, high-potency benzodiazepines (e.g., alprazolam, triazolam) produce rapid CNS re-excitation upon discontinuation, greatly increasing seizure risk.
Question 4: Cocaine's mechanism of action primarily involves:
- Activating dopamine D2 receptors directly
- Blocking reuptake of dopamine, norepinephrine, and serotonin (Correct answer)
- Stimulating dopamine release from presynaptic vesicles
- Inhibiting monoamine oxidase
Correct answer: Blocking reuptake of dopamine, norepinephrine, and serotonin
Cocaine blocks monoamine transporter proteins (DAT, NET, SERT), preventing reuptake and accumulating catecholamines in the synapse.
Question 5: Naltrexone is contraindicated in a client who:
- Has hepatitis C with normal liver enzymes
- Used heroin within the past 7–10 days (Correct answer)
- Is currently on antidepressant therapy
- Has a history of alcohol use disorder
Correct answer: Used heroin within the past 7–10 days
Naltrexone will precipitate acute opioid withdrawal in opioid-dependent clients; a minimum 7–10 day abstinence from short-acting opioids is required before initiation.
Question 6: Which statement best describes the pharmacokinetics of inhaled crack cocaine compared to intranasal powder cocaine?
- Smoked crack has slower onset but longer duration
- Intranasal powder reaches the brain faster due to direct nasal-to-brain transport
- Smoked crack reaches peak brain concentration in seconds, producing a more intense but shorter high (Correct answer)
- Both routes have identical onset and duration
Correct answer: Smoked crack reaches peak brain concentration in seconds, producing a more intense but shorter high
Pulmonary absorption bypasses first-pass metabolism and delivers cocaine to the brain within 8–10 seconds, creating an intense rush that dissipates rapidly and drives compulsive redosing.
Question 7: The Wernicke-Korsakoff syndrome seen in chronic alcohol users is caused by deficiency of:
- Vitamin B12 (cobalamin)
- Thiamine (vitamin B1) (Correct answer)
- Folate
- Niacin (vitamin B3)
Correct answer: Thiamine (vitamin B1)
Alcohol impairs thiamine absorption and utilization; deficiency damages the thalamus and mammillary bodies, producing Wernicke's encephalopathy and, if untreated, Korsakoff's psychosis.