Opioids/Narcotics Flashcards
What mu agonists have the best oral bioavailability?
Methadone and Levophanol
What mu agonists are much more potent then morphine?
Hydromorphone, Oxymorphone, Levorphanol (all -orph)
What mu agonist has a low potency?
Meperidine
What is the inactive metabolite of morphine? What forms it?
Nomorphine
Formed by CYP3A4
What are the active metabolites of morphine? What forms them?
UGT 1A1/2B7 form M-3 and M-6-glucuronide
Dehydrogenase converts morphine-> hydromorphone
How does the half life and oral bioavailability of Methadone different from Morphine? This makes it useful for what?
Methadone- longer half life (27hrs vs 2 for morphine)
Better oral bioavailability (90% vs 20% for morphine)
Useful for withdrawal/maintenance and Detox
What is the Methadone MOA?
Independent of Opioid receptors
Direct effect on IRK channels
What distinguishes Meperidine from the other mu agonists?
Causes mydriasis instead of miosis
Has toxic metabolite normeperidine-> seizures
What is the shortest acting High Potency Full mu Agonist, often used in childbirth?
Remifentanil
What mu agonist acts on kappa, delta, and mu receptors?
Sufentanil
Suffix for high potency full mu receptor agonists?
-entanil (anyl)
What anti-tussive agent receives cough independently of opioid receptors?
Dextromethophan
What kind of agonists are codeine, hydrocodone, and oxycodone? How does it dictate strength of response?
Codeine/Hydrocodone= partial agonists Oxycodone= full agonists-> higher efficacy
What breaks down codeine to morphine?
CYP2D6
What gene duplication will an ultrafast codeine metabolizer have?
CYP2D6 gene duplicaiton-> more morphine then expected
What OTC opioids are used as antidiarrheals?
Loperamide and Diphenoxylate
What opioid acts as both a moderate mu agonist and inhibits catecholamine repute?
Tramadol
What does a partial mu agonist do when taken with morphine? Clinical use?
Displaces morphine-> causes withdraw
Used for office-based detox/maintenance
Classic example-> Buprenorphine
What is the MOA for mu receptor antagonists? What are they called?
Occupy/competitively inhibit other mu agonists from receptors
Antidote for opioid overdose
Naloxone IV and Naltrexone po
What drug can be used as a peripheral acting opioid antagonist to decrease opioid-induced constipation?
Methylnaltrexone
