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.
