Neuromuscular blocking agents: Difference between revisions

Revision as of 03:30, 24 February 2015

Background

Non-depolarizing
- Competitively block binding of ACh to its receptors
Depolarizing
- Depolarizing skeletal muscle fiber
- Persistent depolarization makes the muscle fiber resistant to further stimulation by ACh

Types

Neuromuscular Blocking Agents
Agent	Time to onset (seconds)	Duration (minutes)	Side effects	Clinical use
Non-Depolarizing
Succinylcholine				fasciculations, post-operative pain
Depolarizing
Atracurium (Tracrium)	90	30 min or less^[1]	hypotension, transiently,^[1] by release of histamine Toxic metabolite called laudanosine, greater accumulation in individuals with renal failure	widely^[1]
Cisatracurium (Nimbex)	90	60–80	does not cause release of histamine
Vecuronium (Norcuron)	60	30–40^[1]	Few,^[1] may cause prolonged paralysis^[1] and promote muscarinic block	widely^[1]
Rocuronium (Zemuron)	75	45–70^{[citation needed]}	may promote muscarinic block
Pancuronium (Pavulon)	90	180 or more^{[citation needed]}	tachycardia (slight)^[1] (no hypotension)^[1]	widely^[1]

Sources

↑ ^1.0 ^1.1 ^1.2 ^1.3 ^1.4 ^1.5 ^1.6 ^1.7 ^1.8 ^1.9 Cite error: Invalid <ref> tag; no text was provided for refs named Rang151

Authors:

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[1]

@@ Line 1: / Line 1: @@
 ==Background==
-These drugs fall into two groups:
+*'''Non-depolarizing'''
+**Competitively block binding of ACh to its receptors
-*'''Non-depolarizing blocking agents''': These agents constitute the majority of the clinically relevant neuromuscular blockers.  They act by competitively blocking the binding of ACh to its receptors, and in some cases, they also directly block the [[ionotropic]] activity of the ACh receptors.<ref name="pmid8866353">{{cite journal |author=Bufler J, Wilhelm R, Parnas H, Franke C, Dudel J |title=Open channel and competitive block of the embryonic form of the nicotinic receptor of mouse myotubes by (+)-tubocurarine |journal=J. Physiol. (Lond.) |volume=495 ( Pt 1) |issue= Pt 1|pages=83–95 |year=1996 |pmid=8866353 |doi= |pmc=1160726}}</ref>
+*'''Depolarizing'''
+**Depolarizing skeletal muscle fiber
-*'''Depolarizing blocking agents''': These agents act by [[Depolarization|depolarizing]] the [[sarcolemma]] of the skeletal [[muscle fiber]]. This persistent depolarization makes the muscle fiber resistant to further stimulation by ACh.
+**Persistent depolarization makes the muscle fiber resistant to further stimulation by ACh
 ==Types==
@@ Line 21: / Line 21: @@
 |
 |
-|
+|fasciculations, post-operative pain
 |-
 | '''Depolarizing'''
@@ Line 60: / Line 60: @@
 |-
 |}
-==Comparison of Drugs ==
-The main difference is in the reversal of these two types of neuromuscular-blocking drugs.
-* Non-depolarizing blockers are reversed by [[acetylcholinesterase inhibitor]] drugs since they are competitive antagonists at the ACh receptor so can be reversed by increases in ACh.
-* The depolarizing blockers already have ACh-like actions, so these agents have prolonged effect under the influence of acetylcholinesterase inhibitors. Administration of depolarizing blockers initially produces ''fasciculations'' (a sudden twitch just before paralysis occurs). This is due to depolarization of the muscle. Also, post-operative pain is associated with depolarizing blockers.
 ==Sources==
 <references/>