opioids

Question 1

opioids mechanism of aciton

Answer 1

opioids bind to G-protein coupled receptors, causing closing of voltage gated Ca2+ channels on presynaptic nerve terminals to decrease neurotransmitter release and opening of K+ channels which hyperpolarise neurons, reducing neuronal excitability

Question 2

types of opioid receptors

Answer 2

μ, δ, κ (miu, delta, kappa)

Question 3

Neuropathic pain (pain from diseases or damage directly to sensory neurons) require ___ doses than nociceptive pain (pain from physical/chemical agents)

Answer 3

higher

Question 4

elderly require ___ dose to achieve pain relief than younger patients

Answer 4

lower

Question 5

failure to get partial analgesia with incremental dosing in a patient taking opioids for the first time may indicate that…

Answer 5

pain syndrome is unresponsive to opioid therapy

Question 6

people with chronic pain may not feel analgesic effects until…

Answer 6

a threshold is reached

Question 7

types of opioid agonists (the drugs)

Answer 7

morphine, pethidine, fentanyl, methadone, codeine, tramadol

Question 8

which are the weak opioid agonists

Answer 8

codeine (weak μ and δ agonist)
tramadol (weak μ agonist)

Question 9

which drug is used as epidural

Answer 9

pethidine

Question 10

adverse effects of pethidine

Answer 10

dry mouth, blurring of vision

Question 11

which is a long acting opioid

Answer 11

methadone

Question 12

which opioids are strong agonists with high maximum analgesic efficacy?

Answer 12

morphine, pethidine, methadone, fentanyl

Question 13

which opioid is used as an anaesthetic adjuvant? why?

Answer 13

fentanyl as it is short acting

Question 14

general adverse effects of opioids

Answer 14

• nausea/vomiting, drowsiness, constipation (common)
• miosis (a diagnostic feature of opioid overdose)
• urinary retention
• postural hypotension
• bradycardia
• immunosuppressant effect (long term use)
• respiratory depression (at lethal doses)

Question 15

adverse effect of morphine

Answer 15

cause histamine release from mast cells leading to urticaria and itching, bronchoconstriction and hypotension due to vasodilation

Question 16

which group of people do we use morphine with caution in

Answer 16

asthmatics

Question 17

which receptor is most responsible for both therapeutic and adverse effects?

Answer 17

μ (miu)

therapeutic effects refer to analgesia on the supraspinal, spinal and peripheral level

Question 18

which receptor is most responsible for dysphoria?

Answer 18

κ (kappa)

Question 19

what is the effect after prolonged use of opioids?

Answer 19

development of tolerance i.e. less effective after prolonged and frequent use; need a larger dose to achieve same level of analgesia

Question 20

types of opioid antagonists

Answer 20

naloxone, naltrexone, nalmefene

Question 21

function of opioid antagonists

Answer 21

treat opioid overdose

Question 22

which opioid antagonists are short and long acting respectively?

Answer 22

naloxone - short
nalmefene, naltrexone - long

Question 23

why do we use opioid antagonists with extreme caution

Answer 23

they can precipitate a potentially fatal withdrawal syndrome if too much is given