NMBD Flashcards
What is the definition of NMBD?
Reversible occupation of nicotinic cholinergic receptors by drugs that prevent neuromuscular transmission by restricting Ach access to receptor sites
NMBD result in what?
complete paralysis of striated muscles-most effective way of relaxing muscles
T/F: Animals can retain consciousness when on NMBD?
TRUE
T/F: Respiration ceases when on NMBD due to the effect the drugs have on the diaphragm.
TRUE-Make sure to ensure artificial ventilator support
When are NMBD drugs used?
Microscopic ophthalmic sx, thoracic sx and diaphragm hernia repair, orthopedic sx
What is the MOA of NMBD drugs?
Reversibly occupy postsynaptic nicotinic cholinceptors and prevent neuromuscular transmission by restricting Ach access to these sites
How does a muscle contraction occur?
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
What is an example of depolarizing (non-competitive) NMBD?
Succinylcholine. Depolarize postsynaptic membrane until fatigued leading to muscle paralysis
What is an example of non-depolarizing (competitive) NMBD?
Atracurium, rocuronium, vecuronium, rapacurium. Block interaction of Ach with receptors
What is the order in which NMBD act on specific muscle groups?
Face/muscles of expression –> neck muscles –>diaphragm–> distal limbs –> proximal limbs –>abdominal muscles –> intercostal muscles
T/F: NMBD are water soluble drugs.
TRUE. THey do NOT cross the BBB
What drugs potentiate the effects of NMBD?
Inhalational anesthetic drugs, injectable anesthetic drugs, aminoglycosides, antiarrhythmic drugs, diuretics, Mg
What are the pros and cons to depolarizing NMBD?
Pros: rapid onset, short duration
Cons: muscle fasiculations, muscle contractions, malignant hyperthermia, cardiac arrhythmias, histamine release
What are the two benzylisoquinolinium non-depolarizing NMBD drugs?
Atracurium and cis-atracurium
T/F: Atracurium has slow metabolism due to non-enzymatic degradation which is dependent on pH and temperature
FALSE. Fast metabolism
What is the first NMBD that is free of CV effects?
Vecuronium
What is the shortest and longes acting non-depolarizing NMBD?
Long acting: pancuronium (>30 minutes)
Short acting: Rapacuronium (<10 minutes)
What nerves do you place a peripheral nerve stimulator on in SA vs. equine?
SA: peroneal and ulna n.
Horse: facial n. and superficial peroneal n.
What are the two nerve stimulation patterns?
Single twitch and Train of four
What rate does single twitch stimulate at?
0.1-1 Hz
What is the degree of relaxation for single twitch stimuli?
Degree of relaxation=post NMBD elicited response/pre-relaxant response
What is the degree of relaxation for train of four stimuli?
Degree of relaxation=ratio of intensity of twitch 4/twitch 1
How are NMBD drugs antagonized?
Anti-cholinesterases (edrophonium and neostigmine)
Aminosteroid NMBD can be antagonized with what?
Sugammadex
