Study Set Content:
are sometimes called
• parasympatholytic because they block the effects of
parasympathetic autonomic discharge.
Muscarinic antagonists
Antimuscarinic is
preferable
Other names for muscarinic antagonists
• Cholinergic antagonist
• Cholinergic blockers
• Anticholinergic drugs
Drugs that bind to cholinergic receptors (muscarinic
and/or nicotinic, but do not trigger the usual
intracellular response.
cholinergic antagonist?
THREE SUBCLASS:
(1) Muscarinic blockers
(2) Neuromuscular blocking agents
Ganglionic blockers
inhibit the
efferent impulses to skeletal muscle nicotinic
muscle receptor (NM).
Neuromuscular blocking agents
inhibit the nicotinic
neuronal receptor (N) of both parasympathetic
and sympathetic ganglia.
Ganglionic blockers
MUSCARINIC ANTAGONISTS/ANTIMUSCARINIC
AGENTS
• Atropine
• Scopolamine
• Homatropine
• Cyclopentolate
• Tropicamide pirenzepine
ATROPINE: Therapeutic uses
➢ Bradycardia
➢ Mydriasis & cycloplegia
➢ GI & bladder spasms
➢ Organophosphate poisoning
Duration of action:
4 hours,
4 hours, except when placed
topically in the eye where it lasts for
14 days
ATROPINE: Absorption:
well-absorbed from the GI system &
conjunctiva membrane.
ATROPINE: Excretion:
Excreted through both hepatic
metabolism & renal filtration
ATROPINE: Toxic effects
Dry mouth
• Inhibition of sweating especially in young children
• Tachycardia & cutaneous vasodilation
• Blurring of vision
• Hallucinations & delirium
occurs in Hyoscyamus niger, or
henbane, as the I (-) stereoisomer.
Scopolamine (hyoscine)
Naturally occurring atropine is
is I (-)-hyoscyamine,
Naturally occurring atropine is I (-)-hyoscyamine, but
the compound readily racemizes, so the commercial
material is racemic
d,l -hyoscyamine.
isomers of both alkaloids are at least 100 times
more potent than the d (+) isomers.
The I (-)
A variety of(blank) molecules
have antimuscarinic effects.
semisynthetic and fully synthetic
have been developed to produce more peripheral
effects and reduced CNS effects.
Quaternary amine antimuscarinic agents
