Nondepolarizing neuromuscular blocking agents

Question 1

Nondepolarizing neuromuscular blocking agents - MOA

Answer 1

Competative inhibition of ACh at the muscle type of nicotinic receptors. This inhibits neurotransmission at the skeletal neuromuscular junctions and cause weakness and paralysis.

Question 2

Nondepolarizing neuromuscular blocking agents are also known as…

Answer 2

Curariform drugs

Question 3

Curariform drugs (6 drugs + their classification)

Answer 3

Atracurium (a benzylisoquinoline). 
Cisatracurium (a benzylisoquinoline).
Doxacurium (a benzylisoquinoline).
Pancuronium (an ammino-steroid). 
Rocuronium (an ammino-steroid).
Vecuronium (an ammino-steroid).

Question 4

Nondepolarizing neuromuscular blocking agents - adm

Answer 4

ONLY IV

Question 5

Which drug is the preferred paralytic drug for critically ill pts with renal and hepatic impairments, and why?

Answer 5

Cisatracurium. It decomposes spontaneously through nonenzymatic (Hoffman) degradation.

Question 6

Order of muscle paralysis by curariform drugs

Answer 6

1) Eyes and face.
2) Limbs and face.
3) Intercostals and diaphragm.

Question 7

Nondepolarizing neuromuscular blocking agents - indications

Answer 7

Abdominal surgery (relaxes abd muscles) and other surgeries. 
Adjunct to electroconvulsive therapy to prevent injury by involuntary muscle contractions.
Facilitation of intubation.

Question 8

Curariform drugs - adverse effects and mechanism behind these effects

Answer 8

Hypotension, bronchospasm, salivary and excessive bronchial secretions (increased histamine release from mast cells).
Tachycardia and hypotension (block autonomic ganglia and muscarinic receptors).

Question 9

Which curariform drugs stimulate less histamine release from mast cells and have fewer autonomic side effects? (4 drugs)

Answer 9

Doxacurium.
Cisatracurium.
Rocuronium.
Vecuronium.

Question 10

Curariform drug associated with higher incidence of hypotension and tachycardia

Answer 10

Pancuronium (causes a medium grade of ganglionic blockade)

Question 11

Nondepolarizing neuromuscular blocking agents - interactions (5)

Answer 11

Muscle-relaxing effect is potentiated by: Volatile inhalational anesthetics (sevoflurane), aminoglycosides, tetracyclines, CCBs, neuromuscular disorders (myasthenia gravis)

Question 12

How can the effects of curariform drugs be reversed?

Answer 12

Cholinesterase inhibitors (neostigmine), but only after partial recovery of neuromuscular function.
Sugammadex (clinical testing): may reverse steroidal curariform drugs even during complete paralysis.

Question 13

Nondepolarizing neuromuscular blocking agents with intermediate duration of action (which drugs and time of action)

Answer 13

Atracurium, cisatracurium, rocuronium, vecuronium.

30-60 minutes.

Question 14

Curariform drug that may cause histamine release after high dose adm?

Answer 14

Atracurium

Question 15

Curariform drugs with longer duration of action

Answer 15

Doxacurium.

Pancuronium