L11 - Opioids

Question 1

What types of pain are opioids indicated for?

Answer 1

• both acute and chronic pain
• more effective for nociceptive pain than neuropathic pain
• treatment of moderate to severe pain

Question 2

How do opioids cause analgesia?

Answer 2

• morphine mimics the action of endogenous opioids which act on opioid receptors in the brain and spinal cord as a pain inhibitory system

Question 3

What type of receptor are the opioid receptors? What effect do they have?

Answer 3

• Gi protein receptors
• facilitate opening of K+ channels and inhibit VSCC’s
• cause overall inhibition of neuronal activity

Question 4

What are the opioid receptor subtypes? Where are they located?

Answer 4

• μ 𝛿 κ (the μ receptor responsible for most analgesic and adverse effects)
• located on pre- and post-synaptic neurons

Question 5

What are the desirable effects produced by opioids?

Answer 5

supra-spinal and spinal analgesia

Question 6

What are the adverse effects of opioids?

Answer 6

• euphoria
• respiratory depression
• GI tract effects (reduced GI motility = decreased absorption and constipation)

Question 7

What are the problematic aspects of opioid use?

Answer 7

opioid tolerance and dependence

Question 8

What is opioid tolerance? How long can it take to occur?

Answer 8

• desensitisation to the effects produced by the opioid (desirable and adverse effects not incl. constipation and pupil constriction)
• can occur within 12-24 hour of treatment

Question 9

What is opioid dependence? How can this be avoided?

Answer 9

• onset of withdrawal symptoms upon stopping opioid use

- dependence most severe with short-acting potent opioids like heroin but minimal risk with weak opioids such as codeine

Question 10

What are the low and high efficacy opioids?

Answer 10

low efficacy: codeine

high efficacy: morphine, fentanyl, methadone