Analgesics

Question 1

What do NSAIDs directly bind to

Answer 1

COX enzymes

Question 2

What do opioids directly bind to

Answer 2

G proteins on the neuronal membrane

Question 3

Mechanism of action of NSAIDs

Answer 3

Inhibit the COX enzymes by directly binding; this decreases prostaglandin synthesis.

Question 4

How NSAIDs give an anti-inflammatory effect

Answer 4

Decrease in prostaglandin E2 and prostacyclin decreases vasodilation and oedema.

Question 5

How NSAIDs give an analgesic effect

Answer 5

Less prostaglandin means less sensitisation of nociceptive nerve ending to inflammatory mediators such as bradykinin and 5-HT.

Question 6

How NSAIDs give an antipyretic effect

Answer 6

Less prostaglandins in the CNS means they cannot elevate the hypothalamic set point for temperature control.

Question 7

How do NSAIDs causes gastric bleeding, ulceration?

Answer 7

NSAIDs inhibit gastric COX-1 which usually inhibits acid secretion to protect the mucosa

Question 8

Which enzymes can NSAID anti-inflammatory effect & GI bleed effect be attributed to

Answer 8

Anti-inflammatory effects due to COX-2 inhibition

Unwanted effects, especially GI due to COX-1 inhibition

Question 9

Which ion channels do opiods act on?

Answer 9

Ca2+

K+

Question 10

What are opiods effects on K and Ca channels

Answer 10

Promote opening of voltage-gated K+ channels -decrease neuronal excitability in post-synaptic neuron

Inhibit opening of voltage-gated Ca2+ channel - reduce transmitter release via Ca2+ from pre-synaptic neuron

Question 11

The most troublesome side effects of opiods

Answer 11

Nausea and vomiting
Constipation
Respiratory depression

Question 12

Which voltage-gated channels on sensory neurons does paracetamol effect?

Answer 12

Na+

Ca2+

Question 13

Aside from being a weak COX inhibitor, what is paracetamols mechanism of action

Answer 13

It’s metabolite activates TRPA1 receptor which reduces voltage-gated Na+ and Ca2+ currents in sensory neurones.

Question 14

How does paracetomol differ from other NSAIDs

Answer 14

not anti-inflammatory

but antipyretic and analgesic

Question 15

delta opioid receptors bind this endogenous opioid

Answer 15

enkephalins

Question 16

u opioid receptors bind this endogenous opioid

Answer 16

endorphins

Question 17

k opioid receptors bind this endogenous opioid

Answer 17

dynorphins

Question 18

which opioid receptor is the most important clinically

Answer 18

All opioids used in clinical practice today exert their action, at least in part, at the µ receptor. µ receptor agonism is responsible for the majority of the analgesic properties of opioids.

Question 19

morphine is a archetypal agonist of which receptor

Answer 19

µ opioid receptor (morphine also binds delta and kappa)