NMBD

Question 1

What is the definition of NMBD?

Answer 1

Reversible occupation of nicotinic cholinergic receptors by drugs that prevent neuromuscular transmission by restricting Ach access to receptor sites

Question 2

NMBD result in what?

Answer 2

complete paralysis of striated muscles-most effective way of relaxing muscles

Question 3

T/F: Animals can retain consciousness when on NMBD?

Answer 3

TRUE

Question 4

T/F: Respiration ceases when on NMBD due to the effect the drugs have on the diaphragm.

Answer 4

TRUE-Make sure to ensure artificial ventilator support

Question 5

When are NMBD drugs used?

Answer 5

Microscopic ophthalmic sx, thoracic sx and diaphragm hernia repair, orthopedic sx

Question 6

What is the MOA of NMBD drugs?

Answer 6

Reversibly occupy postsynaptic nicotinic cholinceptors and prevent neuromuscular transmission by restricting Ach access to these sites

Question 7

How does a muscle contraction occur?

Answer 7

AP arrives at pre-junctional alpha motor neuron ending –> nerve terminal becomes depolarized –> conversion of ATP to cAMP results in Ca influx into nerve terminal which further releases Ach into synaptic cleft –> Ach crosses synapse to interact with post-junctional nicotinic receptors resulting in muscle cell action potential and muscle contraction –> Ach rapidly metabolized by acetylcholinesterase in synaptic cleft

Question 8

What is an example of depolarizing (non-competitive) NMBD?

Answer 8

Succinylcholine. Depolarize postsynaptic membrane until fatigued leading to muscle paralysis

Question 9

What is an example of non-depolarizing (competitive) NMBD?

Answer 9

Atracurium, rocuronium, vecuronium, rapacurium. Block interaction of Ach with receptors

Question 10

What is the order in which NMBD act on specific muscle groups?

Answer 10

Face/muscles of expression –> neck muscles –>diaphragm–> distal limbs –> proximal limbs –>abdominal muscles –> intercostal muscles

Question 11

T/F: NMBD are water soluble drugs.

Answer 11

TRUE. THey do NOT cross the BBB

Question 12

What drugs potentiate the effects of NMBD?

Answer 12

Inhalational anesthetic drugs, injectable anesthetic drugs, aminoglycosides, antiarrhythmic drugs, diuretics, Mg

Question 13

What are the pros and cons to depolarizing NMBD?

Answer 13

Pros: rapid onset, short duration
Cons: muscle fasiculations, muscle contractions, malignant hyperthermia, cardiac arrhythmias, histamine release

Question 14

What are the two benzylisoquinolinium non-depolarizing NMBD drugs?

Answer 14

Atracurium and cis-atracurium

Question 15

T/F: Atracurium has slow metabolism due to non-enzymatic degradation which is dependent on pH and temperature

Answer 15

FALSE. Fast metabolism

Question 16

What is the first NMBD that is free of CV effects?

Answer 16

Vecuronium

Question 17

What is the shortest and longes acting non-depolarizing NMBD?

Answer 17

Long acting: pancuronium (>30 minutes)

Short acting: Rapacuronium (<10 minutes)

Question 18

What nerves do you place a peripheral nerve stimulator on in SA vs. equine?

Answer 18

SA: peroneal and ulna n.
Horse: facial n. and superficial peroneal n.

Question 19

What are the two nerve stimulation patterns?

Answer 19

Single twitch and Train of four

Question 20

What rate does single twitch stimulate at?

Answer 20

0.1-1 Hz

Question 21

What is the degree of relaxation for single twitch stimuli?

Answer 21

Degree of relaxation=post NMBD elicited response/pre-relaxant response

Question 22

What is the degree of relaxation for train of four stimuli?

Answer 22

Degree of relaxation=ratio of intensity of twitch 4/twitch 1

Question 23

How are NMBD drugs antagonized?

Answer 23

Anti-cholinesterases (edrophonium and neostigmine)

Question 24

Aminosteroid NMBD can be antagonized with what?

Answer 24

Sugammadex