anticholinergic

Question 1

Scopolamine

Answer 1

Anticholinergic (blocks rest and Digest)
Tertiary Amine (crosses BBB)

Uses;

• preop sedation
• antisialagogue
• bronchodilation
• bradycardia
• mydriasis (pupil dilation)
• prevention of N/V associate with anesthesia
• Antagonism of gastric H+ ion secretion from parietal cells

MOA;
-binds reversibly with muscarinic cholinergic receptors to prevent acetylcholine from binding
(nonselective bind to M1,2, and 3)

Dose;
Pre-op; 0.3 - 0.65 mg IV (may repeat q 4-6 hours)
Transdermal Patch; 5mcg/hr for 72 hrs
2.5cm² patch to hairless area. behind ear night before surgery or 1 hr prior

Pharmacokinetics;
lipid soluble crosses BBB
-E1/2t; 5 hrs
-DOA; IV dose 4-6 hrs; Patch 72 hours

metabolized highly by the liver
1% excreted unchanged by the kidney

Side Effect; (block rest/ digest)

• tachycardia
• palpitations
• orthostatic hypotension
• delayed awakening from anesthesia
• agitation early post op
• sedation/ psychosis/ somnolence
• constipation
• dry mouth/ nose
• rash
• tolerance and loss of therapeutic effect (with patch)

Contraindicated;

• hypersensitivity
• glaucoma
• myasthenia gravis (need acetylcholine to bind)
• tachycardia r/t CV issue
• GI/GU obstruction
• Paralytic ileus

Caution;
-decreases effects of acetaminophen and levodopa (parkinsons pt)

Question 2

Atropine

Answer 2

Anticholinergic (muscarinic receptor antagonist) 
Tertiary Amine (crosses BBB)

Uses;

• bradycardia
• bronchodilation
• antisialagogue
• combo with anti-cholinesterase to reverse NMBD
• anti-cholinesterase OD
• opioid induced biliary spasm
• myodriasis; pupil dilation
• tx hiccups after LMA placement

MOA;
bind to muscarinic receptors and competitively inhibits acetylcholine from binding; blocking rest and digest
-also antagonizes histamine and serotonin

Dose;
-Bradycardia; 0.4 - 1 mg
-Pre-op Antisialagogue; 0.4 - 0.6 mg
-Combo to Reverse NMBD; 7 - 30 mcg/kg 
(edro; 7 - 10mcg/kg)
(neo; 15 - 30 mcg/kg)
(pyridostigmine; 15 - 20 mcg/kg)

Pharmacokinetics;

• onset; 1 min
• E1/2t; 2 hrs
• DOA; 30 - 60 min
• Vd; 1.6 L/kg
• Pb; 40%
• metabolized in the liver into glucuronide conjugates
• 18% excreted unchanged in urine

Side Effects; 
-tachycardia
-arrhythmias
-dry mouth
-urinary retention
-constipation 
-increased IOP
-blurred vision
-inhibits sweating
-crosses BBB; central anticholinergic syndrome;
(respiratory depression, delirium, restless, hallucinations) tx with physostigmine 15 - 60 mcg/kg  

Contraindicatons;

• glaucoma (narrow angle)
• myasthenia gravis (need Ach binding)
• tachycardia would be harmful (CAD, pheochromocytoma)
• hyperpyrexial (really high fever; blocks sweating)

Question 3

Glycopyrrolate (Robinul)

Answer 3

anticholinergic; muscarinic receptor antagonist
quaternary ammonium (does not cross BBB)

Uses;

• bradycardia
• bronchodilation
• antisialagogue
• combo with anti cholinesterase to reverse NMBD

MOA;
binds to muscarinic receptors and competiviely inhibits acetylcholine from binding

Dose; 
-Antisialagogue & Bradycardia; 0.1 - 0.2 mg
-NMBD reversal
7 - 15 mcg/kg w/neostigmine
(0.2 mg for each 1.0mg of neostigmine)

Pharmacokinetics;

• onset; 1 min
• E1/2t; 1hr
• DOA; 2 - 4 hrs
• Vd; 0.2 - 0.4 L/kg

Side Effects;

• tachycardia
• arrhythmias
• dry mouth
• urinary retention
• constipation
• increased IOP
• blurred vision
• inhibits sweating
• Malignant Hyperthermia

Contraindications;

• glaucoma
• tachycardia would be a problem (CAD, CHF, hyperthyroid)