Opiod Analgesics

Question 1

What is the general mechanism of action of opiods?

Answer 1

Stimulation of Mu, Kappa, and delta receptors to cause K+ influx into cells and blocking of Ca+ channels to decrease impulse conduction

Question 2

What are general side effects of opiods?

Answer 2

Vasodilation, sedaton, bradycardia, panting, constipation, vomiting, hypoxia, release of ADH

Question 3

Morphine mechanism?

Answer 3

Mu agonist.

Needs glucouronic liver metabolism into active M6G and M3G

Question 4

Morphine side effects and contraindication?

Answer 4

High incidence of vomiting (80%) // Causes histamine release for vasodilation and myocardial depression
Don’t use in hypovolemic/hypotensive patients

Question 5

Meperidine mechanism?

Answer 5

Synthetic Mu agonist // Causes less excitation in horses & cats // INCREASES HR unlike other opiods

Question 6

Fentanyl mechanism?

Answer 6

Mu agonist // Short acting potent analgesic (100xs potency to morphine) // Has less cardiac and vomiting effects

Question 7

Tramadol mechanism?

Answer 7

Synthetic Mu agonist (1/10th potency of morphine) // moderate analgesic and anti-tussive

Question 8

Codeine mechanism?

Answer 8

Mu agonist (1/10th potency of morphine) // naturally occuring in opium // oral analgesic and anti-tussive

Question 9

Buprenorphine mechanism?

Answer 9

Partial Mu agonist // Binds very strongly to Mu receptor // long acting, but slow onset (30+min)

Question 10

Butorphanol mechanism?

Answer 10

Mu antagonist, Kappa agonist // Antitussive and reversal for Mu agonists // not as much analgesia

Question 11

Naloxone mechanism?

Answer 11

Synthetic opiod antagonist = reversal for agonists but short acting and may require several doses