Neuromuscular Blocking Drugs Flashcards
What is Chondrodendon tomentosum?
A vine from south america that can be used to make a deadly poison.
What are the two categories of non-depolarizing agents?
Isoquinoline derivatives
Steroid derivatives
Which drugs are isoquinoline derivatives?
Atracurium
Cisatracurium
D-Tubocurarine
What drugs are steroid derivatives?
Pancuronium
Rocuronium
Vecuronium
What is the name of the depolarizing agent?
Succinylcholine
What drugs are reversal agents?
Pyridostigmine
Neostigmine
physostigmine
sugammedex
What is the location and function of nicotinic receptors?
- Neuromuscular end plate, skeletal muscle
2. Autonomic ganglion cells
What is the basic structure of the nicotinic Ach receptor?
The Nicotinic Ach receptor is a transmembrane ligand gated Na+ channel that opens when bound to Ach.
What is the fundamental difference in the molecular mechanism of action between the depolarizing and the non-depolarizing NMBs?
The Non-depolarizing agents bind to the Ach binding sites on nicotinic receptors but prevent the channel from opening.
The depolarizing agents bind to the Ach binding site on nicotinic receptors both opening the channels and preventing the channels from closing again for repolarization.
What is the distribution and elimination of the Non-depolarizing NMBs (please name the drugs again)?
Non depolarizing NMBs:
Isoquinolines-Atracurium, Cisatracurium, D-Tubocurarine
Steroids- Pancuronium, Rocuronium, Vecuronium
Rapid initial distribution (Poor protein binding, highly ionized)
Slower elimination
What is special about the metabolism and elimination of atracurium?
Atracurium undergoes hepatic metabolism and Hoffmann elimination
What adverse effect is related to Atracurium metabolism?
Atracurium is matabolized mainly to laudanosine with is causally related to seizures.
What makes Cisatracurium somewhat better than atracurium?
Cisatracurium < dependence on hepatic inactivation, produces <
laudanosine, and releases < histamine
Cisatracurium has all the advantages of atracurium with fewer side effects.
Does succinylcholine have and extremely long or short duration of action? Why?
Succinylcholine has a very short duration of action (5-10 minutes) because it is rapidly hydrolyzed by buyrylcholinesterase in the liver and high capacity pseudocholinesterase in the plasma
Why must we be cautious when we prescribe succinylcholine?
There are many genetic variants of plasma cholinesterase which can drastically impact drug duration.
What can be done to overcome the heterogeneity of plasma cholinesterase?
The dibucaine test is used to identify abnormal variants of plasma pseudocholinesterase.
• Inhibits normal enzyme by 80% and abnormal enzyme by only 20%
What is the elimination route of Atracurium?
Spontaneous