Lecture 11 - Neuromuscular Pharmacology

Question 1

Definition of Neuromuscular Blocking Agent?

Answer 1

paralyse patients undergoing surgery or being ventilated - are NOT sedative, amnesic or analgesic

Question 2

Classifications of NMBAs?

Answer 2

mechanism of action (depolarising and non-depolarising), chemical structure, duration of action (ultra short, short, intermediate, long)

Question 3

Nicotinic ACh receptor?

Answer 3

pentamer, two alpha subunits that need to be binded simultaneously for channel to open

Question 4

Succinylcholine?

Answer 4

mimics Ach, depolarises but doesn’t allow repolarisation, causes fasciculations followed by relaxation, not susceptible to hydrolysis by AChE

Question 5

Succinylcholine and DNMB?

Answer 5

rapid onset, rapid offset (3-5min), ultrashort acting, offset combination of AChE at NMJ and plasma cholinesterases in plasma

Question 6

Dangers of succinylcholine?

Answer 6

potassium rise (catastrophic in upregulated NAChR’s), rasies intracranial pressure, bradycardia, anaphylaxis, malignant hyperpyrexia

Question 7

Benefits of succinylcholine?

Answer 7

ideal for rapid control of airway in a patient w high risk of aspiration (intubation)

Question 8

Non-depolarising neuromuscular blockade?

Answer 8

exerts competitive antagonism, preventing depolarisation, conc. at NMJ declines as drug eliminated, ACh competes out the drug

Question 9

Mivacurium?

Answer 9

short acting, rapid metabolism by plasma esterases responsible for fast offset

Question 10

Atracurium?

Answer 10

intermediate acting, spontaneous degradation independent of liver and kidney; good for hepatic and renal failure

Question 11

Vecuronium?

Answer 11

intermediate acting, lowest risk of histamine release (anaphylaxis)

Question 12

Rocuronum?

Answer 12

intermediate acting, fastest onset, risk of anaohylaxis

Question 13

Pancuronium?

Answer 13

long acting, some effect at muscarinic receptors, leaing to tachycardia

Question 14

Reversal of NMBAs?

Answer 14

to ensure no muscle impairment e.g. respiratory muscles; done by increasing ACh concentration at NMJ and decreasing plasma non-depol NMBAs

Question 15

Drugs for NMBAs reversal?

Answer 15

Neostigmine for AChE inhibition, but this also works on MAChR, so combo with atropine to counter this.

Question 16

Train of four?

Answer 16

4 twitches after admin of NMBAs, EMG response is measured for the twitches, TOF ratio is 4th over 1st, <0.9 ratio means hypoxia risk, diaphragm more resilient but respiratory use still compromised