Analgesics and anaesthesia

Question 1

Weak analgesic/antipyretic

Answer 1

Paracetamol

MoA - Unclear - possible COX inhibitor in CNS

Indications - Mild-moderate pain, pyrexia

Adverse effects - Constipation

Interactions - Warfarin

Question 2

NSAIDs

Answer 2

Ibuprofen, diclofenac, naproxen

MoA - Non-selective COX inhibitors, blockade of prostaglandin synthesis

Indications - Mild-moderate pain, inflammation

Adverse effects - GI disturbance, hypertension, aspirin not suitable for under 16s

Interactions - Diuretics, ACEi

Question 3

COX2-selective NSAIDs

Answer 3

Etoricoxib, celecoxib

MoA - COX2 inhibition, localised prostaglandin blockade

Indications - pain, inflammation

Adverse effects - indigestion

Interactions - ACEi, SSRIs

Question 4

Weak opioid analgesics

Answer 4

Codeine, dihydrocodeine

MoA - Stimulation of analgesic opioid receptors

Indications - Mild-moderate pain

Adverse effects - constipation, nausea

Interactions - sedatives

Question 5

Strong opioid analgesics

Answer 5

Morphine, diamorphine, pethidine, fentanyl

MoA - stimulation of analgesic opioid receptors

Indications - severe pain

Adverse effects - constipation, nausea

Interactions - sedatives

Question 6

Partial/mixed agonist opioid analgesics

Answer 6

Buprenorphine, pentazocine

MoA - Modulation of analgesic opioid receptors (µ and k)

Indications - Moderate to severe pain

Adverse effects - Constipation, nausea

Interactions - sedatives

Question 7

Opioid antagonist

Answer 7

Naloxone, naltrexone

MoA - Opioid receptor antagonist

Indication - Opiate overdose, respiratory depression

Adverse effects - nausea, tachycardia

Question 8

Opioid addiction management

Answer 8

Methadone, buprenorphine

MoA - Narcotic opioid replacement; opioid receptor agonist/modulator

Indications - Opiate addiction

Adverse effects - constipation

Interactions - sedatives

Question 9

Drugs for neuropathic pain

Answer 9

Gabapentin, pregabalin, amitriptyline

MoA - VDCC antagonist (gabapentin, pregabalin)/TCS (amitriptyline)

Indications - Neuropathic pain

Adverse effects - dizziness, fatigue

Interactions - antidepressants

Question 10

Inhaled analgesics

Answer 10

Nitrous oxide + oxygen mixture (“Gas & air”) Entonox

MoA - unclear

Indications - analgesia during childbirth

Adverse effects - Decreased vitamin B12 synthesis

Question 11

General anaesthetic

Answer 11

Propofol, isoflurane, sevoflurane, ketamine
MoA - Unclear - possible enhancement of GABA function (Propofol, isoflurane, sevoflurane)
Ketamine - NMDA receptor blockade

Indications - Induction of anaesthesia throughout major surgery

Adverse effects - hypotension

Question 12

Local anaesthetic

Answer 12

Lidocaine, bupivicaine, levobupivicaine

MoA - Voltage-gated sodium channel blockade

Indications - Local anaesthesia

Adverse effects - Rash

Question 13

Neuromuscular blockers

Answer 13

Atracurium besilate, Vecuronium (non-depolarising)

MoA - Competitive antagonist at AChR

Suxamethonium (depolarising)

MoA - Initially depolarisation and desensitisation of AChR

Indications - Tracheal intubation and mechanical ventilation during surgery

Adverse effects - hypotension, skin flushing

Question 14

Drugs for reversing neuromuscular block

Answer 14

Sugammadex

MoA - Oligosaccharide that forms a complex with NMBs removing them from NMJ

Neostigmine

MoA - Peripheral acetylcholinesterase inhibitor

Indication - Immediate reversal of NMB to reduce post-operative pulmonary complications (sugammadex)
(Neostigmine also used for myasthenia gravis)

Question 15

Temazepam, zolpidem

Answer 15

MoA - GABA PAM (γ-subunit)
Enhanced effects of GABA

Indications - Muscle relaxant and sedative

Question 16

Dexmedetomidine

Answer 16

(alpha-2-agonist)
MoA - Alpha-2 agonists inhibit sympathetic activity

Indications - Muscle relaxant and sedative

Adverse effects - Bradycardia (alpha-2-agonist)

Question 17

Alfentanil, fentanil, remifentanil

Answer 17

(opioids)
MoA - Stimulation of analgesic opioid receptors

Indications - Muscle relaxant and sedative