Drugs in Surgery

Question 1

What two ways are general anaesthetics normally administered?

Answer 1

Intravenously (into the vein) and inhalational

Question 2

What happens to the CNS when you use a general anasthetic?

Answer 2

Its functions are surpressed

Question 3

hat 3 things does depression of CNS functions this lead to?

Answer 3

Supression of conciousness
Supression of pain
Surpression of SKELETAL muscle relflexes

Question 4

What two bad side effects can general anathetics usually do?

Answer 4

Lower blood pressure

Affect respiration

Question 5

What bad thing can rarely happen when using general anaesthetics?

Answer 5

Liver/kidney damage

Question 6

What are the 10 things that make the ideal anaesthetic?

Answer 6

1. Quick induction
2. High potency
3. Reversibility
4. Good analgesic
5. Causes amnesia
6. Causes muscle relaxation
7. Low or harmless metabolism
8. Low toxicity
9. No hangover
10. Non-flammable

Question 7

What does having a quick induction entail?

Answer 7

Having low solubility in the blood so the blood becomes saturated

Question 8

What would give the general anaesthetic a high potency?

Answer 8

Having a high lipid solubility so less of the drug is needed to give a response

Question 9

When it comes to reversibility; would intravenous or inhalational administration be more useful?

Answer 9

Inhalational as you have more control over it than you would intravenous

Question 10

In order for a general anaesthetic to have low toxicity what three things would you want to avoid?

Answer 10

1. Respiratory depression
2. Cardiovascular depression
3. Liver damage

Question 11

What does no hangover from a general anasthetic mean?

Answer 11

Want the effects to wear off after the operation - no drowsiness or sickness

Question 12

What does low or harmless metabolism entail?

Answer 12

We dont want that drug to be broken down into something harmful

Question 13

What kind of molecules are involved in halational anaesthetics?

Answer 13

Small, unreactive molecules

Question 14

What are two examples of small unreactive molecules used as inhalational anaesthetics

Answer 14

Halothane and nitric oxide

Question 15

What sort of concentrations do these inhalational anaesthetics have to be adminstered at?

Answer 15

Very high concentrations

Question 16

Why is halothane a good inhalational general anaesthetic?

Answer 16

It is potent, not irritant and volatile

Question 17

Halothane and nitric oxide dont induce anasthesia; what do they do?

Answer 17

They maintain it

Question 18

What is nitric oxide otherwise known as and what is it used in?

Answer 18

Laughing gas used in childbirth

Question 19

Intravenous agents are very rapid; why is this?

Answer 19

Because of high cerebral blood flow

Question 20

Intravenous agents have a very short duration; why is this?

Answer 20

They are quickly redistrubuted to other organs away from the CNS

Question 21

With it high cerebral blood flow how long does it take for intravenous agents to take affect?

Answer 21

30 seconds

Question 22

What is thiopentone?

Answer 22

A intravenous general anasthetic

Question 23

Why is thipentone known as barbiturate?

Answer 23

It is derived from baribituric acid

Question 24

Why is thiopentone not a good general anasthetic?

Answer 24

It causes cardiovascular and respiratory depression and has a low therpeutic index

Question 25

What did thiopentone used to be used for and why is it not anymore?

Answer 25

Sleeping tablets and because it is fatal if overdosed

Question 26

What happens if you give one dose of thiopentone?

Answer 26

The subject stays asleep for about 5-10 minutes before the affect wears off

Question 27

Why does the effect of thiopentone wear off quickly after only one dose?

Answer 27

It rapidly distrubutes to other organs

Question 28

If you want a longer anathestia using thiopentone what do you have to do?

Answer 28

Repeat the dose so the metabolism is slow

Question 29

Intravenous agents are induction agents; what does this mean?

Answer 29

They are given to induce anathestia before other drugs are given to mentain it

Question 30

When can intravenous agents be used as the only drug?

Answer 30

During short procedures

Question 31

What areas of the brain are involved in GAs analgesic action?

Answer 31

Repression of reticular formation and the thalamus

Question 32

What area of the brain is involved in GAs amnesia action?

Answer 32

Repression of the hippocampus

Question 33

What area of the brain is involved in GAs unconsciousness action?

Answer 33

The reticular formation and the hippocampus

Question 34

What was the old theory of how general anaesthetics worked?

Answer 34

Lipid solubility theory

Question 35

What did the lipid solubility theory entail?

Answer 35

That the GAs interacted with hydrophobic structures which included those on the membrane and increased the fluidity of the membrane

Question 36

What is now the believed mechanism of how GAs work?

Answer 36

They act on GABA receptors

Question 37

What does the GAs acting on GABA receptors do?

Answer 37

Encourages the opening of chloride channels and chloride flooding into the neuron leads to hyperpolatisation and cell inhibition

Question 38

What is hyoscine?

Answer 38

A muscarnic receptor antagonist

Question 39

Why would hyoscine be used a premedication?

Answer 39

Because the parasympathic nervous systems stimulates the glands to secrete muscous so hyoscine would block this and dry up secretions

Question 40

Why would morphine be used as a premedication?

Answer 40

To prevent post operative pain

Question 41

What is lignocaine?

Answer 41

A local anasthetic

Question 42

How does lignocaine act as a loca anastethic?

Answer 42

It blocks sensory nerve conduction

Question 43

In order to relax voluntary muscles what receptors need to be targetted?

Answer 43

Nicotinic receptors

Question 44

What is tubocurraine?

Answer 44

A reversible competitve antagonist of acteylcholine

Question 45

Tubocurraine is non-depolarising; what does this mean?

Answer 45

It blocks the nictonic receptor so does not allow the influx of Na+ ions to cause depolarisation

Question 46

Is tubocurraine long or short acting?

Answer 46

Long

Question 47

How would you stop the effects of tubocurraine?

Answer 47

Inhibition of acteylcholineesterase so there is more ach to compete with the tubocurraine

Question 48

Suxamethonium is a depolarsing drug; what does this mean?

Answer 48

It doesnt block the cation channels like tubocurraine and they stay open leading to hyperpolarisation

Question 49

IS suxamethonium long or short acting?

Answer 49

Short

Question 50

Can suxamethonium be reversed with inhibition of acetylcholineesterate?

Answer 50

No

Question 51

What kind of drug is suxamethonium?

Answer 51

A nictonic receptor agonist