Pharmacology GPAT-2019- Cholinergic Antagonists

Drug
Actions
Therapeutic Uses
Pharmacokinetics
Adverse Effects
Other
Atropine (antimuscarinic)
-bind competitively to muscarinic receptors, blocking the binding of
Ach
-eye: persistent mydriasis, unresponsiveness to light, cycloplegia
-blockage of M1 receptors on presynaptic neurons results in bradycardia (low dose)
-higher doses block M2 receptors on SA node, causing modest increase in cardiac rate
-blocks the salivary glands, causing xerostomia
-affects sweat and lacrimal glands
-GIT: antispasmodic to reduce activity of GIT -used to reduce hypermotility states of bladder
-used for measurement of refractive errors without interference by the accommodative capacity of eye
-Antidote for
cholinesterase inhibitor insecticides and mushroom poisoning 
-Used as an antisecretory agent prior to surgery 
-general actions last about 4 hours 
-topical application in eye can last for days -Half-life for 4 hours -Readily absorbed, partially metabolized by
the liver
-Eliminated in urine
-Results in mydriasis for
7-14 days
-Dry mouth
-Blurred vision
-“Sandy eyes”
-Tachycardia
-Constipation
-Restlessness
-Confusion
-Hallucinations
-Delirium
-Depression, collapse of circulatory and resp. system and death
-tertiary amine belladonna
alkaloid
-ability to enter CNS -atropine toxicity may be
overcome with PHYSOSTIGMINE
-Toxic levels cause dilation of cutaneous vasculature  -May induce acute attack of eye pain in narrow-angle glaucoma patients 
-In children it may induce rapid increase in body temp.
Scopolamine (antimuscarinic)
-blocks short-term memory -produces sedation, but at higher doses it produces excitation -may produce euphoria 
-Most effective anti-motion sickness drug
-Readily absorbed, partially metabolized by
the liver
-Eliminated in urine
-similar to those of
ATROPINE
-tertiary amine belladonna alkaloid
-peripheral effects similar to ATROPINE, but greater CNS effects 
-longer duration of action than
ATROPINE
Ipratropium (antimuscarinic)
-doesn’t enter CNS or systemic
circulation, isolating its effects to
pulmonary system 
-Useful in treating asthma in patients who can’t take adrenergic agonists 
-Management of COPD


-Quaternary derivative of
ATROPINE 
Tropicamide
Cyclopentolate
(antimuscarinic)

-opthalmic solutions for mydriasis and cyclyplegia 
-Tropicamide: 6 hours -Cyclopentolate: 24 hours


Nicotine (ganglionic
-nondepolarizing, competitive antagonist 
-nicotine patches are effective in reducing the

-deleterious to health
-component of cigarette smoke