Opioid agonists & antagonists Flashcards
1
Q
Morphine, methadone, fentanyl
A
- MOA
- strong μ receptor agonists
- variable affinity for δ and κ receptors
- Effects
- analgesia, relief of anxiety, sedation, slowed GI transit
- Clinical
- severe pain, adjunct in anesthesia (morphine, fentanyl), pulmonary edema (morphine), maintenance in rehab programs (methadone)
- Kinetics, tox
- first pass effect
- duration 1-4h except methadone - 4-6h
- tox: respiratory depression, severe constipation, addiction liability, convulsions
2
Q
Codeine
A
- MOA
- partial agonist
- less efficacious than morphine, can antagonize strong agonists
- Effects
- like strong agonists, weaker effects
- Clinical
- mild-moderate pain, cough
- Kinetics, tox.
- like strong agonists, toxicity dependent on genetic variation of metabolism
3
Q
Buprenorphine
A
- MOA
- mixed opioid agonist-antagonist
- partial μ agonist, κ antagonist
- Effects
- like strong agonists but can antagonize their effects
- reduces craving for alcohol
- Clinical
- moderate pain, some maintenance rehab programs
- Kinetcs, tox.
- long duration of action 4-8h
- may precipitate abstinence syndrome
4
Q
Dextromethorphan
A
- Antitussive (also codeine)
- MOA
- poorly understood but strong and partial μ agonists are also effective antitussives
- Effects
- reduces cough reflex
- dextromethorphan not analgesic
- Clinical
- acute debilitating cough
- Kinetics, tox.
- 30-60min duration
- tox: minimal when taken as directed
5
Q
Naloxone
A
- MOA
- antagonist at μ, δ, κ receptors
- Effects
- rapidly antagonizes all opioid effects
- Clinical
- opioid overdose
- Kinetics, tox.
- duration 1-2h, may have to be repeated
- tox: precipitates abstinence syndrome
6
Q
Tramadol
A
- MOA
- mixed effects: weak μ agonist, moderate SERT inhibitor, weak NET inhibitor
- Effects
- analgesia
- Clinical
- moderate pain, adjunct to opioids in chronic pain syndromes
- Kinetics, tox.
- duration 4-6h
- tox: seizures, risk of serotonin syndrome
