atropine (Atropair, Atropine-Care)

Indications

• surgery
  • used with general anesthesia
  • pre-operative medication to reduce salivation & excessive secretions of the respiratory tract
  • used to prevent cholinergic effects during surgery
• cardiology
  • hypotension
  • bradycardia
    • treatment of choice for symptomatic bradycardia (class I)
  • AV block
    • may be beneficial (class IIa) for treatment of AV block at the nodal level or ventricular asystole
• amblyopia
• antidote for muscarinic toxidrome
  • organophosphate poisoning (pesticides), carbamate toxicity, anticholinesterase toxicity (physostigmine)
  • mushroom poisoning
• ophthalmic agent - mydriasis & cycloplegia for examination of the retina & optic disc
• diarrhea: used in combination with diphenoxylate in Lomotil
• irritable bowel syndrome
• urinary incontinence, neurogenic bladder
• sialorrhea

Contraindications

• asthma
• narrow angle glaucoma (ophthalmic)
• atropine is no longer recommended for pulseless electrical activity (PEA)
• atropine may be best avoided in patients with
  • type II second degree heart block
  • new onset type III heart block with wide QRS complexes,
  • these rhythms are frequently secondary to anteroseptal myocardial infarction, resulting in a conduction system defect at the His-Purkinje level
  • diminished vagal tone will not help these patients

pregnancy category = c

safety in lactation = -

safety in lactation = ?

Dosage

• 0.4-0.6 mg PO, SC, IM, IV every 4-6 hours
• pre-operative: give 30-60 minutes prior to induction of anesthesia
• ACLS: 1 mg IV, repeat in 3-5 minutes, max 0.03 mg/kg
• endotracheal: 2-2.5 x the IV dose in 10 ms of normal saline

Tradenames: Isopto Atropine, Atropair, Atropine-Care. Mydriasis: 1 drop QD-TID for 7-14 days Cycloplegia: 1 drop QD-TID for 5-10 days

0.5 % 1.2%

Pharmacokinetics

• well absorbed throught the GI tract:
  • absorbed in upper small intestine
  • peak plasma levels in 1 hour
• IM injection: peak plasma levels in 30 min
• endotracheal administration:
  • absorbed well through the endotracheal route
  • peak plasma concentrations in 1.5-4 hours
  • a total dose of 3 mg produces total vagal block in humans
• limited amounts cross the blood-brain barrier
• maximal mydriasis in 30-40 minutes with duration of action of 7-12 days
• maximal cycloplegia in several hours with duration of action of 2 weeks

elimination via kidney

1/2life = 2-3 hours

Adverse effects

• common (> 10%)
  • dry, hot skin
  • impaired GI motility
  • constipation
  • dry mouth & throat
  • irritation at site of injection
  • dry nose
  • decreased sweating
• not common (1-10%)
  • photophobia, decreased flow of breast milk, dysphagia
• uncommon (< 1%)
  • orthostatic hypotension, tachycardia, palpitations, ventricular fibrillation, confusion, drowsiness, ataxia, fatigue, delirium, headache, memory impairment, restlessness, rash, nausea/vomiting, difficulty urinating, tremor, weakness, intraocular pain, blurred vision, mydriasis
• other
  • dizziness, bronchospasm
• toxicity
  • fever, delirium

• drug adverse effects of parasympatholytics

Drug interactions

• additive effects when co-administered with other anticholinergic agents
• may alter absorption of other drugs

• drug interaction(s) of parasympatholytic with parasympathomimetic

Laboratory

• atropine in hair
• atropine in blood
• atropine in serum/plasma
• atropine in urine

Mechanism of action

• antimuscarinic agent that competitively inhibits action of acetylcholine
• dose-dependent anti-muscarinic activity
• relative degree of sensitivity
  • secretions of salivary, bronchial & sweat glands
  • pupillary dilatation
  • ocular accomodation
  • increased heart rate
  • contraction of the detrussor muscle of the bladder & smooth muscle of the GI tract
  • gastric acid secretion & motility
• blocks action of acetylcholine at muscarinic receptor sites in the smooth muscle of the iris

More general terms

• belladonna alkaloid
• parasympatholytic (anticholinergic, antimuscarinic agent)
• mydriatic agent
• cycloplegic agent
• antidote
• anti-motility agent; antiperistaltic agent

More specific terms

• hyoscyamine (Anaspaz, Levsin)

Additional terms

• bradyarrhythmia (bradycardia)
• pulseless electrical activity; electromechanical dissociation (PEA)

Component of

• atropine/hyoscyamine/scopolamine
• atropine/hyoscyamine/phenobarbital/scopolamine
• atropine/chlorpheniramine/hyoscyamine/pseudoephedrine/scopolamine
• atropine/benzoic acid/hyoscyamine/methenamine/methylene blue/phenyl salicylate
• atropine/edrophonium
• atropine/pralidoxime (Duodote)
• atropine/diphenoxylate (Lomotil, Lonox)
• atropine/belladonna/hyoscyamine/phenobarbital/scopolamine (Donnatal)
• atropine/attapulgite/hyoscyamine/scopolamine (Donnagel)
• atropine/difenoxin (Motofen)

Database

• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=3661
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=174174