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Anticholinergics. Jacob Hummel M.D. Tulane University Anesthesiology. Know the different mechanisms of action for atropine, scopolamine and glycopyrrolate Clinical use of each of these drugs Effects on the cardiovascular, respiratory, cerebral, G.I. and other organ systems. Objectives. - PowerPoint PPT Presentation
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Jacob Hummel M.D.Tulane University Anesthesiology
Anticholinergics
*Objectives
*Know the different mechanisms of action for atropine, scopolamine and glycopyrrolate
*Clinical use of each of these drugs
*Effects on the cardiovascular, respiratory, cerebral, G.I. and other organ systems
*Disclosures
*This is a really short lecture but its brevity does not reflect the value of its content
*Antimuscarinics
*This term is more indicative of what these drugs accomplish as they are primarily blocking the effects of acetylcholine at the muscarinic receptors
*Antimuscarinics
*Primary use is prior or concomitant administration with anticholinesterases
*Crucial in the treatment of bradycardia
*Beneficial in the prevention of PONV
*Antisialogogues
*The Antimuscarinics
*
*Structure and Binding
*Ester linkage essential for effective binding to the acetylcholine receptors, competitively inhibiting the binding of acetylcholine
*Different types of muscarinic receptors: neuronal (M1), cardiac (M2), and glandular (M3)
*Systemic Effects
*CARDIOVASCULAR*Blockade of the muscarinic receptors in the
sinoatrial node results in tachycardia
*Useful for reversing vagal reflexes
*Systemic Effects
*RESPIRATORY*Inhibit secretions along the respiratory tract
*Relaxes bronchial smooth muscle -> decreased airway resistance but increased dead space
*Systemic Effects
*CEREBRAL*Range of effects, stimulation to depression*Physostigmine reverses these occurrences
*Systemic Effects
*G.I.*Decreased secretions and salivation*Decreased peristalsis*Lower esophageal sphincter pressure
reduced
…better view, but more at risk for aspiration
*Systemic Effects
*Other Effects*Mydriasis*Urinary retention*Reduced sweating, rise in body temp
*Atropine
*Potent effects on the heart and lungs*Most efficacious for
treating bradycardia*Tertiary amine allows it
to cross blood-brain barrier*Derivative is ipratropium
bromide and used to treat bronchospasm*Use cautiously with heart
disease, narrow angle glaucoma, BPH and bladder-neck obstruction
Give me the atropine, NOW!
*Scopolamine
*Similar dosing to atropine, 0.01-0.02 mg/kg with adult dose around 0.4 - 0.6 mg*More potent
antisialogogue than atropine*Greater CNS effects*Lipid solubility allows for
the transdermal patch*Don’t touch your eyes
after you put a patch on someone!
*Glycopyrrolate
*Contains mandelic acid in place of the tropic acid seen in atropine*Dosing is usually half of the atropine dosing and used
for similar effects (bradycardia, antisialogogue, etc.)*Quaternary structure prevents crossing of the blood-
brain barrier*No ophthalmic activity*Potent antisialogogue*Longer duration of action than atropine (2-4 hrs. vs
30 minutes)
*Case Discussion
*An elderly patient is scheduled for enucleation of a blind, painful eye. Scopolamine, 0.4 mg intramuscularly, is administered as premedication. In the preoperative holding area, the patient becomes agitated and disoriented
The only other medication the patient has received is 1% atropine eye drops
*…how do you treat and would you proceed with the case?
*Anticholinergic Poisoning
*Signs and Symptoms*Agitation, delirium, unconsciousness*dry mouth, tachycardia, atropine flush,
atropine fever, and impaired vision
…antidote is physostigmine as it is the only anticholinesterase to cross the blood-brain barrier
*Proceed with the case?
*Elective Procedure*Is patient optimally medically managed?*Do symptoms resolve with intervention?
*Thanks for your attention
*GENERAL HUMMEL FROM ALCATRAZ….OUT!
*References