Opioids

Question 1

Outline the action of opioids

Answer 1

Peripheral = inhib release of substance P (neurotransmitter)

GPCRs opioid receptor binding = increased outward K = decreased excitability = decreased Ca influx = decreased cAMP = decreased neurotransmitter release

Question 2

Describe the pathways involved in pain

Answer 2

Pain transmission from the dorsal horn

Inhibitory descending pathways from higher centres in the brain – A-beta fibres

Question 3

What are the different classes of opioid receptors?

Answer 3

Mu – supra spinal

Delta – spinal cord

Kappa – widely distributed

Question 4

What are the major therapeutic uses of opioids?

Answer 4

Analgesia moderate to severe = morphine, methadone, tramadol

Analgesia mild = codeine

Anaesthetics = fentanyl

Question 5

What are the ADRs from using opioids?

Answer 5

Mu = nausea, vomiting, constipation, drowsiness, miosis, resp depression

Kappa = dysphoria (state of unease)

Question 6

Discuss fentanyl

Answer 6

Analgesia and well as an anaesthetic when with other meds

Rapid onset, lasts 1-2 hours

Activates Mu receptors

Commonly administered via patches