Neuromuscular blocking drugs Flashcards Preview

LCRS Y2: Pharmacology and Therapeutics > Neuromuscular blocking drugs > Flashcards

Flashcards in Neuromuscular blocking drugs Deck (28):
1

Give 3 examples of NMJ blockers

Tubocurarine
Atracurium
Suxamethonium

2

What is the method of action of tubocurarine?

Competitively antagonises nicotinic ACh receptors

3

What % block of nAChRs is required for total muscle relaxation?

70-80%

4

What sort of paralysis is produced by total nAChR block?

Flaccid

5

Recall the distinctive relax-and-return pattern seen in nAChR-antagonist-induced muscle relaxation

Relax in this order, reverse in opposite order:
Extrinsic eye muscles
Small muscles of face/limbs/pharynx
Respiratory muscles

6

What drug class is used to reverse the action of NMJ-blocking drugs? What is the caveat to this?

anti-cholinesterases - but only for POLARISING NMJ blockers

7

Give an example of an anti-cholineesterase

Neostigmine

8

Why is neostigmine always given with atropine?

Neostigmine increases [ACh] in all other cholinergic synapses so you give some atropine with it so that it blocks the muscarinic receptor over stimulation

9

Give 2 clinical uses of spasmolytics

Cerebral palsy
Spasticity following stroke

10

Give 2 clinical uses for suxamethonium

Endotracheal intubation
Muscle relaxant for electroconvulsive therapy

11

Recall the mechanism of action of spasmolytics

Potentiate effects of GABA

12

Give 2 examples of spasmolytics

Diazepam
Baclofen

13

Recall the mechanism of action of diazepam

Facilitates GABA transmission

14

Recall the mechanism of action of baclofen

GABA receptor agonist

15

What sort of drug is atracurium?

Non-depolarising NMJ drug (= ANTagonist)

16

Give an example of a depolarising NMJ drug?

Suxamethonium

17

What is a depolarising NMJ drug?

Depolarising = agonist

18

Recall the mechanism of action of suxamethonium

Causes Phase 1 Block by extending end-plate depolarisation

19

What is a fasciculation?

Individual muscle fibre twitches

20

What is a possible side effect of suxamethonium?

Fasciculations

21

Recall the structure of suxamethonium

2 ACh molecules stuck together

22

What is the normal method of administration and duration of action of suxamethonium?

IV - 5-10 minutes

23

Describe the metabolism of suxamethonium

Metabolised by pseudocholinesterase in the liver and plasma

24

Describe the structure of non-depolarising NMJ drugs

big and bulky with limited rotation around bonds

25

What must always be done when suxamethonium is administered?

Assist respiration

26

Recall 4 side effects of suxamethonium and the reasons for each

1. Post-operative muscle pain (initial fasciculations)
2. Bradycardia (direct muscarinic activation at heart)
3. Hyperkalaemia (only in de-innervation supersensitivity)
4. Raised IOP

27

What are the 2 main causes of unwanted side effects of tubocurarine?

1. Overlap onto ganglionic nAChRs (despite preferential muscle action)
2. Histamine leakage out of mast cells

28

Recall 5 unwanted side effects of tubocurarine

1. Hypotension
2. Tachycardia
3. Bronchospasm (from histamine release)
4. Excessive secretions
5. Apnoea