Pharmacology of Addictive Substances Flashcards

Which receptor subtype is primarily responsible for the euphoric effects of opioids?

Answer: Mu (μ)

Mu (μ) opioid receptors mediate euphoria, analgesia, and respiratory depression, making them the primary target for opioid misuse.

A patient on buprenorphine/naloxone reports that injecting the medication produces little to no euphoria. Which pharmacological property of naloxone best explains this?

Answer: Naloxone blocks opioid receptors when administered parenterally

Naloxone has poor sublingual bioavailability but becomes active when injected, blocking opioid receptors and precipitating withdrawal, deterring misuse.

Cocaine's primary mechanism of action involves blocking the reuptake of which neurotransmitter most responsible for its reinforcing effects?

Answer: Dopamine

Cocaine blocks dopamine transporter (DAT), causing dopamine accumulation in the nucleus accumbens, which drives its reinforcing and euphoric effects.

Which benzodiazepine property makes diazepam particularly prone to misuse compared to oxazepam?

Answer: Diazepam has a faster onset of action due to higher lipophilicity

Diazepam's high lipophilicity allows rapid CNS penetration and faster onset, producing a more intense euphoric effect that increases its misuse potential.

Which mechanism explains why alcohol withdrawal can be life-threatening, unlike opioid withdrawal?

Answer: Alcohol causes upregulation of GABA-A receptors leading to CNS hyperexcitability upon cessation

Chronic alcohol use downregulates GABA-A receptors and upregulates NMDA receptors; abrupt cessation causes CNS hyperexcitability, risking seizures and death.

Naltrexone reduces alcohol cravings primarily by which pharmacological mechanism?

Answer: Blocking opioid receptors that mediate alcohol-induced dopamine release

Naltrexone blocks mu-opioid receptors, preventing the endorphin-mediated dopamine release that reinforces alcohol consumption.

A patient who smokes methamphetamine develops severe hyperthermia and rhabdomyolysis. Which pharmacological mechanism most directly contributes to hyperthermia?

Answer: Massive norepinephrine release causing peripheral vasoconstriction and excess heat retention

Methamphetamine causes massive norepinephrine release, producing intense vasoconstriction that impairs heat dissipation and raises core body temperature.