LCAS Pharmacology of Addictive Substances 1 — Questions and Answers
Question 1: Which neurotransmitter is most centrally involved in the mesolimbic reward pathway associated with substance use disorders?
- Serotonin
- Dopamine (Correct answer)
- GABA
- Norepinephrine
Correct answer: Dopamine
Dopamine is the primary neurotransmitter in the mesolimbic reward pathway, and surges in dopamine release are the central mechanism underlying the reinforcing effects of addictive substances.
Question 2: Which of the following correctly describes the primary mechanism of action of opioids in the central nervous system?
- They block dopamine reuptake in the nucleus accumbens
- They bind to mu, kappa, and delta opioid receptors (Correct answer)
- They enhance GABA-A receptor chloride conductance
- They antagonize NMDA glutamate receptors
Correct answer: They bind to mu, kappa, and delta opioid receptors
Opioids exert their analgesic and euphoric effects primarily by binding to mu-opioid receptors (as well as kappa and delta receptors) distributed throughout the brain and peripheral nervous system.
Question 3: Alcohol produces CNS depression primarily by which pharmacological mechanism?
- Blocking dopamine D2 receptors
- Stimulating serotonin 5-HT3 receptors exclusively
- Enhancing GABA-A inhibitory activity and inhibiting NMDA glutamate receptors (Correct answer)
- Blocking norepinephrine reuptake transporters
Correct answer: Enhancing GABA-A inhibitory activity and inhibiting NMDA glutamate receptors
Alcohol enhances inhibitory GABA neurotransmission and inhibits excitatory glutamate activity at NMDA receptors, producing the characteristic CNS depressant effects.
Question 4: In addiction pharmacology, 'tolerance' is best defined as:
- The ability to function normally despite intoxication
- The requirement for increasing doses to achieve the same effect previously produced by a lower dose (Correct answer)
- Physical symptoms that occur when drug use is discontinued
- The psychological craving for a substance between uses
Correct answer: The requirement for increasing doses to achieve the same effect previously produced by a lower dose
Tolerance develops when repeated substance exposure leads to diminished pharmacological effects, requiring progressively higher doses to achieve the original response.
Question 5: Which opioid's long half-life (24–36 hours) produces withdrawal symptoms that are less intense but more prolonged compared to short-acting opioids?
- Heroin
- Hydrocodone
- Methadone (Correct answer)
- Oxycodone
Correct answer: Methadone
Methadone's long half-life means blood levels decline slowly, producing a withdrawal syndrome that is milder in peak intensity but extends over a longer period than short-acting opioids.
Question 6: The concurrent use of two or more psychoactive substances is clinically referred to as:
- Cross-tolerance
- Synergism
- Polysubstance use (Correct answer)
- Potentiation
Correct answer: Polysubstance use
Polysubstance use describes the simultaneous or concurrent use of multiple psychoactive substances, which complicates assessment, treatment planning, and withdrawal management.
Question 7: Stimulants such as cocaine and amphetamines primarily produce euphoria by which mechanism?
- Binding to opioid receptors in the limbic system
- Blocking the reuptake of dopamine, norepinephrine, and serotonin (Correct answer)
- Enhancing GABA-A inhibitory postsynaptic potentials
- Directly activating cannabinoid CB1 receptors
Correct answer: Blocking the reuptake of dopamine, norepinephrine, and serotonin
Stimulants block monoamine reuptake transporters, causing accumulation of dopamine, norepinephrine, and serotonin in the synapse, which produces intense euphoria and increased arousal.
LCAS Pharmacology of Addictive Substances 1
Which neurotransmitter is most centrally involved in the mesolimbic reward pathway associated with substance use disorders?