Drugs used in surgery

Question 1

General anaesthetics

Answer 1

Many central nervous system functions suppressed

• loss of consciousness
• suppression of pain
• suppression of skeletal muscles

toxic effects:
depress b.p. and respiration (low therapeutic index)
-liver/kidney damage (rare)

Question 2

Characteristics of the ideal anaesthetic

Answer 2

• quick induction (low solubility in blood)
• high potency -high lipid solubility
• reversibility-gases give good control
• good analgesia
• amnesia
• no hangover

Question 3

Characteristics of the ideal anaesthetic (ii)

Answer 3

• low or harmless metabolism
• non-flammability
• muscle relaxation
• low toxicity
• eg. respiratory depression, cardiovascular depression, liver damage

Question 4

1. Volatile/ gaseous anaesthetics

Answer 4

• halothane and nitrous oxide are commonly used

- small molecules, numerous

Question 5

2. Intravenous agents

• induction agents
• short procedures
• thiopentone
• ketamine
• etomidate
• propofol
• diazepam
• midazolam

Answer 5

• I.V injection
• very rapid (high cerebral blood flow), short duration (redistribution to other organs)
• e.g THIOPENTONE (barbiturate) depresses heart and respiration
• repeat dose -longer anaesthesia (slow metabolism)

Question 6

General anaesthetics enhance the action of …

Answer 6

opening if chloride channels (eg GABA receptors)

-Cl- entry into neurone –> hyperpolarisation and inhibition

Question 7

PREMEDICATION

Answer 7

-hyoscine - muscuranic receptor antagonist - dries up secretions of saliva and bronchial mucus

Question 8

Lignocaine

Answer 8

local anaesthetic, blocks conduction in sensory nerves

Question 9

Muscle relaxant drugs: tubocuranine

Answer 9

• non-depolarising
• competes with ACh
• long acting
• reversible with ChE inhibitor

Question 10

Muscle relaxant drugs: suxamethonium

Answer 10

• depolarising
• cation channels stay open
• short acting
• not reversible with ChE inhibitor