Ch 11 - Pain Medicine: Opioid Pharmacology Flashcards
What are the presynaptic actions of opioids?
Lower influx of Ca to reduce NT release in sensory C fibers
What are the postsynaptic actions of opioids?
Inc the transport of K in the cell to facilitate hyperpolarization in 2nd order neurons
Opiates activate the chemoreceptor trigger zone in the medulla, which leads to ____.
GI SE of nausea and vomiting
Opioid receptor type Mu1 causes
Analgesia
Opioid receptor type Mu2 causes
Respiratory depression Sedation Vomiting Euphoria Anorexia Physical dependence Pruritus
Opioid receptor type Delta causes
Analgesia
Spinal analgesia
Opioid receptor type Kappa causes
Analgesia Sedation Psychomimetic effects Dyspnea Respiratory depression Euphoria Dysphoria
Lipid-soluble drugs exert most of their effect at ___.
Localized areas where they are administered
ex) fentanyl
What are the endogenous opioids?
Leu-Enkephalin
Beta-Endorphin
Dynorphin A&B
What are the opioid agonists?
Morphine Diamorphine (heroin) Fentanyl Meperidine Methadone
What are the opioid antagonists?
Naloxone
Naltrexone
What are the partial opioid agonists?
Buprenorphine
Pentazocine
MOA of oxycodone
Mu agonist
Metobalites of Oxycodone
Oxymorphone
Noroxycodone
MOA of Oxymorphone
Opioid agonist
Metabolites of Oxymorphone
6-Hydroxy-oxymorphone
MOA of Hydromorphone
Mu agonist
Metabolites of Hydromorphone
Hydromorphone-3-Glucuronide
MOA of Tramadol
Weak Mu agonist
Weak NE/5HT reuptake inhibitor
Contraindication for Tramadol
CI with MAOI or SSRI d/t serotonin syndrome
MOA of Morphine
Mu agnoist
Metabolites for Morphine
Morphine-3-glucuronide
Morphine-6-glucuronide
Hydromorphone
Contraindication for Morphine
Do not use in renal failure
MOA of Meperidine
Weak mu agonist
Metabolites of Meperidine
Normeperidine
Contraindication for Meperidine
Do not administer with MAOI
MOA of Hydrocodone
Mu and kappa agonist
Metabolites of Hydrocodone
Dihydrocodeine
Hydromorphone
MOA of Methadone
Mu and delta agonist
NE and 5HT reuptake inhibitor
NMDA antagonist
Metabolites of Methadone
2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) (inactive)
Contraindication for Methadone
May cause QT
prolongation
MOA of Fentanyl
Mu agonist
Metabolites of Fentanyl
Norfentanyl
MOA of Buprenorphine (Subutex or Suboxone)
Partial mu and kappa agonist, delta antagonist Suboxone contains naloxone (receptor antagonist)
MOA of Pentazocine (Talwin)
Kappa agonist, mu antagonist
MOA of Butorphanol (Stadol)
Kappa agonist, mu antagonist
MOA of Nalbuphine (Nubain)
Kappa agonist, mu antagonist
How can opioids cause respiratory sedation?
Acts on brainstem to reduce sensitivity of the respiratory centers to PCO2
How can opioids suppress coughing?
Inhibitory effect on the brainstem nuclei in the cough reflex pathway (common use for codeine)
How do opioids cause constipation?
Maintained contraction of the smooth muscles in the gut (and therefore decreased motility)
How do opioids cause sexual dysfunction?
Correlated to hypogonadism and associated with lower testosterone levels (erectile dysfunction, decreased libido)
