Pain pharmacology

Question 1

Action of paracetamol?

Answer 1

Pain: stops prostaglandin synthesis in the CNS (decreasing glycine inhibition). Inhibits reuptake of endogenous cannabinoids.
Anti inflammatory: reduces active form of COX2

Question 2

Ibuprofen

Answer 2

NSAID. Mild-moderate. Inhibits COX1 and COX2. Decreases PG formation. Reduces sensitisation.

Question 3

Major side effect of ibuprofen?

Answer 3

Inhibition of COX1- prostaglandins that protect guy mucosa. Peptic ulcers.

Question 4

Diclofenac

Answer 4

NSAID. Moderate-severe. Inhibits prostaglandin formation. Inhibits phospholipase A2 and reduction in arachidonic acid.

Question 5

Diclofenac side effects

Answer 5

Lower COX1 selectivity so no GI. Higher risk of CV complications.

Question 6

Amitriptyline- pain

Answer 6

TCA. Neuropathic pain- depression, insomnia. Mainly snri like. Inhibits sodium, L type calcium, some k. NMDA receptors. Muscarinic alpha 1, alpha 2 adrenoreceptors

Question 7

Amitriptyline side effects

Answer 7

Weigh gain, muscle stiffness, constipation, dry mouth, postural hypotension, nausea, dizziness. Anticholinergic

Question 8

Pregabalin- pain

Answer 8

Anticonvulsant. Alpha 2 delta1 subunit N type calcium channels. Decreased neurotransmitter release

Question 9

Tramadol

Answer 9

Atypical opioid. Moderate-severe. Mu receptors. Slight snri like. Better side effect profile than opiates. Anticholinergic side effects- nausea, constipation

Question 10

Morphine

Answer 10

Opioid. Mu receptors. Decrease excitability. Stimulate PAG and inhibit SC in lamina 2. Reduce anxiety.