Analgesia (PD Week 4)

Question 1

Name an opioid antagonist

Answer 1

naloxone

Question 2

name 3 opioid agonists

Answer 2

morphine
diamorphine
codeine

Question 3

why do opioids in overdose cause respiratory depression

Answer 3

there are lots of u-receptors in the respiratory area - increased activation can lead to decreased sensitivity which leads to being unable to control hyperventilation which can lead to death

Question 4

How do opioids act on the descending pathway

Answer 4

opioids excite PAG neurons and NRPG which stimulate the NRM the 5-HT/NA neuron of the descending path releases 5-HT and NA - these inhibit presynaptic substance P and glutamate release it also stimulate the interneuron to release enkephalins

enkephalins inhibit substance p and glutamate presynaptic release
enkephalins inhibit postsynaptic neuron from depolarising

Question 5

What is meant by tolerance

Answer 5

when a person’s reaction to a drug decreases such that larger doses are needed to achieve the same effect

Question 6

What is meant by drug dependence

Answer 6

an adaptive state that develops from repeated drug administration which results in the emergence of physical and emotional withdrawal symptoms upon cessation of drug use

Question 7

What is the underlying mechanism of tolerance in relation to morphine

Answer 7

receptor becomes desensitised due to repeated activation

morphine tolerance involves phosphorylation of u-opioid receptors

Question 8

What happens to some opioid receptors upon repeat activation

Answer 8

they become internalised or degraded by lysosomes inside the cell

Question 9

How can we prevent opioid abuse

Answer 9

• ensure proper prescription
• screen for drug abuse
• patients must follow prescribed prescription