Pharmacology of Substance Abuse Flashcards

A client with an alcohol use disorder is prescribed disulfiram (Antabuse). The counselor should explain that this medication works by:

Answer: Causing a severe adverse reaction when alcohol is consumed by inhibiting aldehyde dehydrogenase.

Disulfiram works by inhibiting the enzyme aldehyde dehydrogenase, which is crucial for metabolizing alcohol. When a person taking disulfiram consumes alcohol, acetaldehyde builds up in the body, leading to a highly unpleasant and toxic reaction known as the disulfiram-ethanol reaction. This reaction serves as a powerful deterrent to drinking.

A client who uses cocaine reports an intense 'rush' followed by a 'crash'. From a pharmacological perspective, the initial intense euphoria is primarily caused by cocaine's action of:

Answer: Blocking the reuptake of dopamine in the brain's reward pathway.

Cocaine is a powerful stimulant that primarily works by blocking the dopamine transporter (DAT). This blockage prevents the reabsorption of dopamine from the synapse, leading to a significant increase in the concentration and duration of dopamine in the brain's reward centers, such as the nucleus accumbens. This surge of dopamine is responsible for the intense euphoria or 'rush' users experience.

Which of the following best describes the mechanism of action for benzodiazepines like diazepam (Valium) and alprazolam (Xanax)?

Answer: They are positive allosteric modulators of GABA-A receptors.

Benzodiazepines exert their sedative, anxiolytic, and muscle-relaxant effects by binding to a specific site on the GABA-A receptor, which is distinct from the GABA binding site. This binding enhances the effect of the inhibitory neurotransmitter GABA, allowing more chloride ions to enter the neuron. This process makes the neuron less likely to fire, resulting in central nervous system depression. This is known as positive allosteric modulation.

A client is being considered for medication-assisted treatment for alcohol use disorder and reports a goal of complete abstinence. They have no liver problems but struggle with cravings. Which medication works by modulating the glutamate and GABA neurotransmitter systems to help maintain abstinence?

Answer: Acamprosate

Acamprosate (Campral) is thought to work by restoring the balance between the excitatory neurotransmitter glutamate and the inhibitory neurotransmitter GABA, which is disrupted by chronic alcohol use. By stabilizing this balance, it can reduce the protracted withdrawal symptoms like insomnia, anxiety, and restlessness, thereby reducing cravings and helping to maintain abstinence.

A client who has been using heroin for several months abruptly stops. Within 8-12 hours, they begin to experience muscle aches, anxiety, runny nose, and excessive yawning. These symptoms are characteristic of:

Answer: Acute opioid withdrawal

The symptoms described are classic early signs of acute opioid withdrawal. For short-acting opioids like heroin, withdrawal symptoms typically begin within 6-12 hours after the last dose. These initial symptoms often resemble a severe flu and include anxiety, muscle aches, lacrimation (tearing), rhinorrhea (runny nose), and yawning.

Which of the following correctly distinguishes buprenorphine from methadone in the treatment of opioid use disorder (OUD)?

Answer: Methadone can only be dispensed through federally regulated opioid treatment programs (OTPs).

While both are effective medications for OUD, a key regulatory and practical difference is their dispensing. Methadone, a full opioid agonist, is highly regulated and, for the treatment of OUD, can generally only be dispensed through specialized opioid treatment programs (OTPs). Buprenorphine, a partial agonist, can be prescribed by qualified practitioners in office-based settings, increasing its accessibility.