Drugs in Surgery Flashcards Preview

Drugs and Disease > Drugs in Surgery > Flashcards

Flashcards in Drugs in Surgery Deck (33):
1

What are the ways to take general anaesthetics (GAs)?

Inhalational
Intravenous

2

What are premedications?

Muscarinic antagonist
Analgesic
Local anaesthetic
Muscle relaxant

3

What do GAs do?

Abolish awareness and response to pain

4

Why are GAs used in surgery?

Loss of consciousness, including memory
Suppression of pain
Suppression of skeletal muscle reflexes and tone

5

What are the toxic effect of GAs?

Depresses b.p. and resiration (low therapeutic index)
Liver/kidney damage (rarely)

6

What are the characteristics of the ideal anaesthetic?

Quick induction
High potency
Reversibility
Good analgesia
Amnesia
No hangover
Low or harmless metabolism
Non-flammability
Muscle relaxation
Low toxicity

7

What is quick inductio?

Low solubility in blood, giving rapid saturation of bloos

8

What is high potency?

High lipid solubility

9

What is reversibility?

Gases give good control, injection less so

10

What is low toxicity?

Respiratory depression
Cardiovascular depression
Liver damage

11

What are volatile/ gaseous anaesthetics?

Many, simple, unreactive compounds
Halothane and nitrous oxide are commonly used

12

What is the compositiong of volatile/gaseous anaesthetics?

Numerous simple, small molecules
Mostly very unreactive compounds

13

What happens with intravenous agents after injection

Very rapid (high cerebral blood flow)
Very short duration (redistribution to other organs)

14

What is an example of an intravenous agent used?

Thiopentone (barbiturate)

15

What are the characteristics of thiopentone?

Low therapeutic index
Depresses heart and respiration
Repeat dose-> longer anaesthesia (slow metabolism)

16

What are intravenous agents?

Induction agents
Short procedures

17

What are the mechanism of intravenous mechanisms?

Synaptic transmission, not axonal conduction

18

Where is analgesia caused in intravenous mechanisms?

Reticular formation and thalamus

19

Where is unconsciousness caused in intravenous mechanisms?

Rf and hippocampus

20

Where is amnesia caused in intravenous mechanisms?

hippocampus

21

What mechanism was recognised by is now discredited?

Non-receptor

22

What is the lipid-solubility mechanism?

Interact with hydrophobic structure
Membranes- volume expansion (pressure reversal)
Protein binding (hydrophobic sites)

23

What do receptors encourage?

Opening of chloride channels (e.g. GABA receptors)

24

What does Cl- entry into a neurone cause?

Hyperpolarisation and inhibition

25

What do general anaesthetics do in terms of the Cl- entering the neurone?

Enhance the response

26

What drugs are used as a premedication?

Hyoscine
Morphine
Lignocaine

27

What is hyoscine?

Muscarinic receptor antagonist- dries up secretions of saliva and bronchial mucus

28

What is morphine?

Opiate analgesic
Prevents post-operative pain

29

What lignocaine?

Local anaesthetic- blocks conduction in sensory nerves

30

What do muscle relaxant drugs do?

Voluntary muscles can be relaxed by drugs which interfere with nicotinic receptors

31

What are some examples of muscle relaxant drugs?

Tubocurarine
Suxamethonium

32

What does tubocurarine do?

Non-depolarising
Competes with ACh
Long acting
Reversible with ChE inhibitor

33

What does suxamethonium do?

Depolarising
Cation channels stay open
Short acting
Not reversible with ChE inhibitor