Opiods Flashcards
Opioids (General)
**Uses: Analgesic
***Mechanism: Main active substance is MORPHINE which acts as an agonist at receptors for endogenous opioid. Opioid receptor is “G protein-coupled receptor”
***Found in CNS and GI
*Opioid receptor subtypes:
MU = main site of action for morphine
KAPPA = site of some drugs (pentazocine)
Signs of Opioid Overdose (OD)
1) Reduced consciousness
2) Respiratory depression
3) Constriction of pupils (miosis)
Morphine
Uses: Analgesia
Mechanism: MU Agonist
Potency: 10mg Intramuscular or Subcutaneous
Time Action: peak at 1 hour, or minutes w/ IV. Duration is 4-6 hours
**Oral Potency: is only 1/12 to 1/6 of intramuscular potency
Selectivity: Standard
Heroin
*also called “Diactylemorphine”
Use: Analgesia, recreation
Mechanism: MU agonist
Potency: 3-5 times the potency of Morphine
Time action: similar to morphine
Oral potency: —-
Selectivity: like Morphine, no special analgesic or euphoric action. Heroin has low activity (monoacetyl morphine and morphine provide most action
Codeine
Uses: Antitussive (stop coughing), minor analgesia
**Mechanism: MU agonist
***Potency: 1/12 potency of morphine BUT EQUAL ANTITUSSIVE
Time action: —-
Oral potency: Good, Methyl group protects first pass
Selectivity: Like morphine, antitussive, dysphoria w/ high dose
Hydrocodone
Use: Antitussive?
Mechanism: MU Agonist
Potency: —-
Time-action: —-
Oral Potency: Fair
***Selectivity: Like codeine, metabolism ends to hydromorphone which accumulates in patients with renal failure
**Added to other medications for antitussive effects
Dextromethorphan
**Uses: Antitussive (combined with other drugs),
no analgesic action
***Mechanism: Maybe sigma receptors, NMDA-type glutamate receptor. Not a true opiod
Meperidine (Demerol)
Uses: Analgesia
Mechanism: MU agonist
Potency: —
Time action: Faster onset (<1hr), shorter duration (2-4 hours)
Oral potency: fair
Selectivity: like morphine, some toxic metabolites, less constipation, no significant antitussive activity
***Toxicity: Has typical opioid toxicity PLUS nor-meperidine metabolite causes CNS excitation. Also it interacts with MAO inhibitors causing SERATONIN SYNDROME
Diphenoxylate (Loperamide)….loperamide is Immodium, but maybe don’t need to know this card for exam
**Uses: Control Diarrhea
**Mechanism: MU inhibitor to gut of opioid receptors (online it says MU agonist that decreases activity of myenteric plexus???)
Potency: low, low abuse liability
Time action: —
Oral potency: high
Selectivity: low solubility means it doesn’t cross blood brain barrier. Stays in Gut and increases tone.
***Fentanyl
**Uses: Analgesia, control breakthrough pain in those already tolerant
**Mechanism: MU agonist
**Potency: 80-100 times the potency of morphine
Time action: Very short duration due to redistribution
Oral potency: Very low, not used orally
Selectivity:
***Becoming more abused and can cause death b/c of higher potency
Methadone
Uses: Analgesic, Acute: treat dependence, Chronic: “maintenance” part of treatment for addiction
Mechanism: MU agonist -Potency like morphine -Time action: similar after single dose but long after multiple doses -Oral potency: Good Selectivity: like morphine
Accumulation occurs since 24 hr half life steady state not reached till 5 days!
Less peaks and valleys!
Oxycodone
Uses: Antitussive analgesic
*Mechanism: MU Agonist
*Potency: similar to codeine but more potent
Time action: Time release tablets are made (OxyContin)
Oral potency:
Selectivity:
*Taken w/ Acetaminophen = Percocet
*Naloxone (Narcan)
- Uses: Anti-opiod OD (overdose) medication, life-saving for families, SHORT-ACTING; production of constipation
- Mechanism: Opioid COMPETITIVE Antagonist at MU, Kappa, and Delta receptors
Selective dose dependent reversal of opioid agonist effects.
**W/Physical dependence will precipitate immediate/intense “abstinence syndrome”
SHORT duration of action
First pass biotransformation
Naltrexone
Uses: treat addiction (of opioid and also approved for ethanol addiction), LONG-ACTING ANTAGONIST
Mechanism: Opioid receptor antagonist
Pentazocine
Use:
Mechanism: Kappa agonist and MU antagonist (weak partial agonist)
*Lower potency and limited efficacy than morphine
*Shorter time action
Good oral potency
May precipitate abstinence in dependent patients, Not a partial agonist, can increase BP, dysphoric at high dose
