Flashcards in Neuromuscular blocking drugs Deck (28):
Give 3 examples of NMJ blockers
What is the method of action of tubocurarine?
Competitively antagonises nicotinic ACh receptors
What % block of nAChRs is required for total muscle relaxation?
What sort of paralysis is produced by total nAChR block?
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
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
Give an example of an anti-cholineesterase
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
Give 2 clinical uses of spasmolytics
Spasticity following stroke
Give 2 clinical uses for suxamethonium
Muscle relaxant for electroconvulsive therapy
Recall the mechanism of action of spasmolytics
Potentiate effects of GABA
Give 2 examples of spasmolytics
Recall the mechanism of action of diazepam
Facilitates GABA transmission
Recall the mechanism of action of baclofen
GABA receptor agonist
What sort of drug is atracurium?
Non-depolarising NMJ drug (= ANTagonist)
Give an example of a depolarising NMJ drug?
What is a depolarising NMJ drug?
Depolarising = agonist
Recall the mechanism of action of suxamethonium
Causes Phase 1 Block by extending end-plate depolarisation
What is a fasciculation?
Individual muscle fibre twitches
What is a possible side effect of suxamethonium?
Recall the structure of suxamethonium
2 ACh molecules stuck together
What is the normal method of administration and duration of action of suxamethonium?
IV - 5-10 minutes
Describe the metabolism of suxamethonium
Metabolised by pseudocholinesterase in the liver and plasma
Describe the structure of non-depolarising NMJ drugs
big and bulky with limited rotation around bonds
What must always be done when suxamethonium is administered?
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
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