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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.
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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
This is a really short lecture but its brevity does not reflect the value of its content Disclosures
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 Antimuscarinics
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) Structure and Binding
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 Systemic Effects
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! Atropine
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! Scopolamine
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) Glycopyrrolate
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? Case Discussion
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 Anticholinergic Poisoning
Elective Procedure • Is patient optimally medically managed? • Do symptoms resolve with intervention? Proceed with the case?
GENERAL HUMMEL FROM ALCATRAZ….OUT! Thanks for your attention