Pharmacology of Opioid Addiction (Asbill)

Define drug addiction

Loss of control, craving, compulsive use, continued use despite harm, and relapse vulnerability.

Define tolerance

Reduced response after repeated exposure; higher dose may be needed to achieve the same effect.

Define sensitization

Some effects can be enhanced after repeated use or after abstinence; overdose risk increases after a drug-free period.

Define dependence

Physiologic adaptation: stopping opioids or giving an antagonist can precipitate withdrawal.

What are the biological risk factors of addiction?

genes

gender

mental disorder

age

method if administration

What are the environmental risk factors of addiction?

stress

peer influence (family, friends, work)

early use

availability

cost

How do opioids decrease GABA release?

reduce cAMP

reduce Ca influx

increase K efflux/ hyperpolarization

T/F: The increase in NE due to lower levels of GABA release is why OUD develops

False

Opioid-induced respiratory depression is most directly related to opioid effects on respiratory centers that include which structure?

pre-Bötzinger complex in the brainstem

μ-Opioid receptor activation within the reward pathway can increase dopamine signaling through which mechanism?

reduced GABA-mediated inhibition of dopamine neurons

A patient with opioid use disorder is started on buprenorphine. Which pharmacologic property of buprenorphine best explains this effect?

partial agonist activity

A 62-year-old patient with metastatic cancer has received morphine for several months. Initially, 10 mg provided adequate analgesia, but the patient now requires 20 mg to achieve a similar effect. The patient has not demonstrated compulsive drug-seeking behavior.

Which cellular adaptation most likely contributes to this change in response?

Receptor desensitization and internalization following repeated opioid exposure

A patient who has used opioids chronically completes an extended period of abstinence and then returns to a previously tolerated dose. Shortly afterward, the patient develops profound respiratory depression.

Which pharmacologic concept best explains the increased overdose risk?

Loss of tolerance during abstinence