Neuromuscular Blocking Agents
Summary of Effects:
Eye: Mydriasis and cycloplegia
Bronchi: Little effect
GI tract: Motility; constipation
Contractility of bladder
Impaired erection and ejaculation
Heart: Slight HR
NITRIC OXIDE MEDIATED VASODILATION
ACh activates muscarinic receptors in endothelial cells that triggers Nitric Oxide
(NO) formation. NO is a potent vasodilator.
CARDIOVASCULAR ACTIONS OF ATROPINE
o Low dose - decrease
o High dose increase
Depolarizing Blockers Succinlycholine
Cause initial activation of skeletal muscle
Produces a transient fasciculation of muscle
Similar to that produced by Ach
Activates or drives NM so that the NMJ endplate stays depolarized,
Muscarinic Receptor Blocking Agents
Muscarinic receptor blockade does not interfere with transmission at autonomic
ganglionic sites, the adrenal medulla, or skeletal muscle fibers. Sympathetic
adrenergic functions are not affected.
MUSCARINIC RECEPTOR BLO
Neuromuscular Blocking Drugs
Non-depolarizing blockers are reversed by 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
M2 and M3 Muscarinic Receptor Antagonists
M2 MUSCARINIC RECEPTOR ANTAGONISTS
Blocks the M2 receptor
Blocks the action of acetylcholine at cardiac muscle fibers
Blocks M2 muscarinic and the NN nicotinic receptors
M3 MUSCARINIC REC
Therapeutic Uses of Succinylcholine
o Adjunct to ECT (to prevent trauma)
o Some diagnostic tests: endoscopy; bronchoscopy
Note: No need for pharmacological reversal of neuromuscular blockade by
o Pharmacology - potent anti-muscarinic, shows selectivity for the urinary bladder
o Therapeutic use -reduce urinary urgency
o Cytochrome P450
o Active metabolite is DD-01 (variations of Cytochrome P450 then will not effect
SCOPOLAMINE: Angels Trumpets
Source Belladonna Plant
Lower doses of scopolamine (0.1 - 0.2 mg) produce greater cardiac slowing than an
equivalent dose of atropine.
Higher doses produce tachycardia
Low doses of scopolamine produce CNS effects that are not
Pharmacologic Actions of ANS
Absorption and Distribution
Poorly absorbed from the GI tract.
Thus given by slow iv infusion.
Effect is rapid (within 2-3 minutes) and short acting (10 minutes).
Undergoes rapid elimination.
Hence the need for slow infusion r