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anticholinergic drugs
CVM
61
Medical
Graduate
03/15/2010

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Term
what are the three types of anticholinergic drugs?
Definition
antimuscarinics (atropine, propantheline - inhibit cholinergic transmission at postganglionic para-sympathetic receptor sites), ganglionic blocking agents (mecamylamine, trimethaphan - block cholinergic transmission at autonomic ganglia in both parasympathetic and sympathetic nerve fibers), and neuromuscular blockers (not covered this year)
Term
what is the term anticholinergic primarily used to denote?
Definition
muscarinic (G-protein coupled) blockers, which have relatively selective blocking action
Term
what happens with an overly large dose of any of the anticholinergics?
Definition
loss of specificity of receptor blocking action - wide range of ADRs
Term
what are the major organs affected by anticholinergic drugs?
Definition
since parasympathetic nerves are distributed throughout the body, anticholinergic drugs can affect the eye, resp tract, heart, GI tract, urinary bladder, most nonvascular smooth muscle, exocrine glands and the CNS
Term
what are the major pharmacologic effects of anticholinergic drugs on the GI?
Definition
decreased motility, secretions -> constipation (interfernce with vagal control)
Term
what are the major pharmacologic effects of anticholinergic drugs on the CV?
Definition
tachycardia (though small doses of atropine can produce bradycardia)
Term
what are the major pharmacologic effects of anticholinergic drugs on the urinary tract?
Definition
contraction of the sphincter muscle/relaxation of detrusor muscle, resulting in urinary retention
Term
what are the major pharmacologic effects of anticholinergic drugs on the eye?
Definition
relaxation of the ciliary muscle: cyclopelagia (paralysis of accomodation), relaxation of the sphincter muscle: mydriasis (excessive dilation of the pupil) - relaxation for the fundoscopic exam
Term
what are the major pharmacologic effects of anticholinergic drugs on the exocrine glands?
Definition
decreased sweating, salivation and mucous formation (problem in geriatric pts with swallowing)
Term
what are the major pharmacologic effects of anticholinergic drugs on the smooth muscle?
Definition
relaxation of non-vascular smooth muscle (biliary, bronchiolar, intestinal, uterine)
Term
what are the major pharmacologic effects of anticholinergic drugs on the CNS?
Definition
decreased sensitivity to motion, drowsiness, disorientation, possible hallucinations, decreased skeletal muscle activity (similar to alzheimer's)
Term
what are the different kinds of muscarinic blockers?
Definition
belladonna alkaloids, tertiary and quaternary amines
Term
what are the principal naturally occuring anticholinergic drugs?
Definition
the belladone alkaloids atropine and scopolamine. they are are similar but the oxygen added to scopolamine can make a patient a little more drowsy. cocain has a similar structur to atropine
Term
what is the M/A for the belladonna alkaloids atropine and scopolamine?
Definition
competetive antagonistic blockage of postsynaptic muscarinic ACh receptors. large doses block cholinergic transmission at autonomic ganglia and the neuromuscular junction.
Term
how rapidly are belladona alkaloids absorbed? are they selective in blocking action of muscarinic receptors? can they penetrate the CNS?
Definition
they are absorbed rapidly PO, they are relatively selective in blocking action at M receptor sites, and readily enter the CNS. there is a wide range however, of undesirable peripheral and central effects even when used therapeutically
Term
what are uses of the belladonna alkaloids atropine and scopolamine in eye exams, preop, GI issues, myastenthia tx, allergies, and asthma?
Definition
mydriasis and cycloplegia for eye exam, preop reduction of salivation/bradycardia, reduction of GI motility/secretions in cases of peptic ulcer, GI spasms, irritable bowel syndrome, or other GI disorders. reduction of muscarinic side effects assoicated with myasthenia anticholinesterase tx, relief of nasopharyngeal/broncial secretions associated with allergic disorders, relief of bronhoconstriction due to excessive parasympathetic nerve activity in bronchia asthma/other chronic obstructive pulmonary disease
Term
what are uses of the belladonna alkaloids atropine and scopolamine in motion sickness, enuresis, sinus bradycardia/conduction block, sedation, cholinergic OD, and parkinsons?
Definition
belladona alkaloids can be used in prevention/relief from motion sickness, treatment of enuresis as well as urinary urgency, tx of sinus bradycardia/conduction block due to excessive vagal tone, production to sedation/amesia (twilight sleep), antidoe to cholinergic OD/pesticides, relief of parkinsons symptoms and control of extrapyramidal disorders resulting from antipsychotic meds
Term
how are the belladonna alkaloids absorbed?
Definition
atropine and scopolamine are absorbed rapidly from the GI tract and eye. scopolamine is also absorbed significantly throuh the skin behind the ear when applied as a transdermal patch
Term
what are belladonna alkaloid ADRs for the GI?
Definition
dry mouth, vomiting, dysphagia, bloating, constipation, paralytic ileus, possibly gastroesophageal reflux
Term
what are belladonna alkaloid ADRs for the CV?
Definition
tachycardia, facial flushing, HTN
Term
what are belladonna alkaloid ADRs for the CNS?
Definition
headache, confustion, drowsiness, nervousness, restlessness, insomnia, delirium, hallucinations, elevated body temp
Term
what are belladonna alkaloid ADRs for the eye?
Definition
blurred vision, photophobia, cycloplegia, increased intraocular tension
Term
what are belladonna alkaloid ADRs for the skin?
Definition
rashes, urticaria, systemic allergic reactions
Term
what are belladonna alkaloid ADRs for the GU?
Definition
urinary retention, dysuria, impotence
Term
what are other general belladonna alkaloid ADRs?
Definition
reduced sweating, suppression of lactation, possible respiratory depression
Term
what are possible contraindication for belladonna alkaloids?
Definition
narrow angle glaucoma, *severe coronary artery disease, GI obstruction/intestinal atony/paralytic ileus/hepatic disease/ulcerative colitis, renal obstruction/disease, and myasthenia gravis
Term
what drugs can increase the effects of the belladona alkaloids?
Definition
antihistamines, tricyclic anti-depressants, antipsychotics, anti-anxiety drugs, quinidien, procainamide
Term
what drugs can decrease the effect of the belladonna alkaloids?
Definition
antacids that can impair GI absorption
Term
what drugs might antimuscarinics enhance the effects of?
Definition
bronchodilators (adrenergics, theophylline)
Term
what drug's effect might be decreased by antimuscarinics?
Definition
cholinergics such as pilocarpine or physostigime
Term
what are the tertiary amines?
Definition
dicyclomine, oxybutin, oxyphencyclimine, cyclopentolate, tropicamide, benztropine, trihexyphenidyl, diphenhydramine, and ethopropazine
Term
what are the benefits of the tertiary amines?
Definition
they are well absorbed PO, have good lipid-solubility, and are widely distributed into peripheral/central tissues
Term
what are the antispasmotic tertiary amine anticholinergics?
Definition
dicyclomine for IBS, oxybutinin for bladder instability, and oxyphencyclimine for peptic ulcers
Term
what are the mydriatic tertiary amines? what are they used for?
Definition
cyclopentolate (24 hr duration) and tropicamide (6 hr duration) are used to produce mydriasis/cycloplegia for eye exams b/c they have shorter durations than the belladona alkaloids
Term
what are possible ADRs for the mydriatic tertiary amines?
Definition
disorientation, retrograde amnesia, hallucinations, cardiac arrhythmias (a-fib/supraventricular tachycardia), and death in children
Term
what are the antiparkinson's/anti-extrapyramidal disorder tertiary amine anticholinergics? how do they work?
Definition
benztropine, trihexyphenidyl, diphenhydramine, and ethopropazine are used to balance ACh and dopamine (parkinsons = dopamine deficiency, extrapyramidal disorders = dopamine blockage) these are more selective than belladonna alkaloids.
Term
what are the peripheral ADRs associated with the antiparkinson's/anti-extrapyramidal disorder tertiary amine anticholinergics?
Definition
constipation, urinary retention, and tachycardia
Term
what is benztropine used for? trihexyphenidyl?
Definition
**benztropine: initiation of therapy, trihexyphenidyl: maintenance of therapy
Term
what is diphenhydramine?
Definition
benadryl, an antihistamine with central anticholinergic activity. it has less peripheral side effects than other agents, and has a sedative effect
Term
what is ethopropazine?
Definition
a antiparkinson's/anti-extrapyramidal disorder tertiary amine with a high degree of peripheral anticholinergic action and less efficacy than other agents
Term
what are the quaternary amines? what are they mainly used for?
Definition
clindinium, glycopyrrolate, methantheline, and propantheline which are mainly used for reduction of gastric acid secretion in tx of peptic ulcers. they can also be used for decreasing GI/bile motility in spastic disorders, and decreasing motility of urinary tract in a hypertonic neurogenic bladder
Term
what are problems with the quaternary amines?
Definition
low degree of lipid solubility, poor/erratic adsorption, and limited systemic distribution (do not cross BBB)
Term
what is seen with small doses of quaternary amines?
Definition
inhibition of sweating, salivation, and bronchial secretions. *smaller doses will inhibit secretions but not the target
Term
what is seen with medium doses of quaternary amines?
Definition
mydriasis, cycloplegia, tachycardia, decreased gastric acid secretion, decreased GI/urinary motility
Term
what is seen with large doses of quaternary amines?
Definition
delirium
Term
what is glycopyrrolate used for?
Definition
preanesthetic used to decrease saliva, reduce secretions of GI/resp tracts, prevent bradycardia, and reduction of gastric acid secretion in treatment of peptic ulcers
Term
when is methantheline used? propantheline?
Definition
methantheline is usually used for tx of hypertonic neurogenic bladder, propantheline is more potent. both can also be used for reduction of gastric acid secretion in treatment of peptic ulcers
Term
what is clindinidum used for?
Definition
reduction of gastric acid secretion in treatment of peptic ulcers
Term
how are ganglionic blocking agents generally classified? what are the 2 kinds of ganglionic blocking agents?
Definition
anticholinergic drugs that act *primarily at postsynaptic cholinergic sites within autonomic ganglia are termed ganglionic blocking agents and they are divided into depolarizing and nondepolarizing categories.
Term
what is a depolarizing ganglionic blocking agent?
Definition
nicotine, an alkaloid, which intially stimulates the postsynaptic ganglionic receptor causing elevated BP, HR, GI motility, CNS stimulation and respiration - but with large doses and systemic absorption, repolarization of the membrane can be prevented - blocking stimulation and leading to reduced BP, increased HR, confusion, convulsions, and respiratory failure
Term
how do the non-depolarizing ganglionic blocking agents work?
Definition
nonselective (both symp and parasymp) competetive antagonism of ACh at receptor sites of ganglia in the ANS
Term
what are the net effects of non-depolarizing ganglionic blocking agents?
Definition
the net effects are dependent on which division of the ANS has primary control of the organ/system. if symp: marked vasodilation, (orthostatic hypotension), and decreased venous return (decreased cardiac output). parasymp: decreased GI motility/secretions, dry mouth, urinary retention, constipation, cycloplegia & mydriasis, and impotence
Term
what are the two non-depolarizing ganglionic blocking agents?
Definition
mecamylamine and trimethaphan which are powerful BP reducing drugs but are infrequently used due to the wide range of side effects
Term
what is mecamylamine used for?
Definition
mecamylamine has good absorption from the GI and enteres the CNS. management of moderate to severe essential HTN and uncomplicated malignant HTN when other antihypertensive drugs have failed
Term
what are contraindications for mecamylamine use? ADRs?
Definition
ADRs are consistent with those usually seen with anticholinergics, and contraindications are for coronary insufficiency and recent MI. rapid termination should be avoided due to possible occurence of HTN rebound
Term
what is trimethephan often used for?
Definition
if a pt has a hypertensive crisis
Term
what are other effects of trimethaphan?
Definition
direct relaxant effect on vascular smooth muscle and histamine release
Term
how is trimethaphan in terms of duration of action and interactions with other drugs?
Definition
it works for 10-30 min and has a physical incompatibility with other IV solutions (does not mix)
Term
what are restricted uses of trimethaphan?
Definition
producing controlled hypotension during sx, acute control of BP in HTN emergencies, and control of blood pressure in cases of acute dissecting aortic aneurysm
Term
what are the ADRs associated with trimethaphan?
Definition
primary anticholinergic
Term
what drugs can help with a trimethaphan OD?
Definition
phenylephrine and mephentermine: vasopressor drugs of choice to reverse significant hypotension
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