II. Pharmacology

  1. Tertiary ammonium alkaloid ester of tropic acid
  2. Naturally occurs in plant sources
    1. Atropa belladonna (Deadly nightshade)
    2. Datura stramonium (Jimsonweed, Thorn apple)
  3. Described as Belladonna (beautiful woman) alkaloid
    1. Women of past used Atropine to dilate pupils
    2. Mydriasis was perceived as more attractive
  4. Related isomer to Scopolamine (Hyoscine)

III. Mechanism

  1. Antimuscarinic Cholinoceptor blocking drug
  2. Causes parasympathetic blockade (parasympatholytic)
  3. Inhibits vagal nerve activity (vagolytic)
    1. Enhances Sinus node automaticity
    2. Enhances Atrioventricular Node (AV) conduction

IV. Indications

  1. Symptomatic Bradycardia associated with
    1. Poor perfusion
    2. Hypotension
  2. Relative Bradycardia
  3. Prevent vagally mediated Bradycardia with intubation
  4. Symptomatic Bradycardia with AV Block
  5. Asystole or Pulseless Electrical Activity
    1. No evidence that survival is improved with Atropine
    2. Asystole is nearly always fatal despite intervention

V. Pediatric Dosing

  1. IV Dose
    1. Dose: 0.02 mg/kg IV or IO
    2. Minimum Dose: 0.1 mg
    3. Maximum Dose
      1. Child: 0.5 mg
      2. Adolescent: 1.0 mg
  2. Endotracheal Dose
    1. Dose: 2-3x IV dose (0.06 mg/kg) diluted in 3-5cc NS
    2. Follow dose with several positive pressure breaths

VI. Adult Dosing

  1. Bradycardia
    1. Dose: 0.5-1.0 mg IV
    2. May repeat q3-5 min to max total dose of 0.04 mg/kg
  2. Asystole or Bradycardic Pulseless Electrical Activity
    1. Dose: 1 mg IV
    2. Consider giving entire 0.04 mg/kg at start)
    3. May repeat q3-5 min to max total dose of 0.04 mg/kg
  3. Endotracheal Dosing
    1. Dose: 1-2 mg per dose
    2. Dilute to 10 ml with sterile water or saline

VII. Precautions

  1. Avoid repeat dosing if possible
    1. Increases myocardial oxygen demand
    2. Atropine may provoke Ischemic Heart Disease
  2. Consider external pacing if repeat dosing needed
  3. Avoid dosing Atropine below recommended dose
    1. Causes paradoxical Bradycardia
    2. May precipitate Ventricular Fibrillation

VIII. Adverse effects

  1. Rebound Tachycardia
  2. Paradoxical Bradycardia (if low dose Atropine used)
  3. Pupil dilatation (Mydriasis)
  4. Paradoxical rate slowing
    1. Type II Second degree AV Block
    2. Third Degree AV Block
  5. Arrhythmia (especially in Coronary Artery Disease)
    1. Ventricular Fibrillation
    2. Ventricular Tachycardia
  6. Anticholinergic Toxicity with overdosage
  7. Decreased Sweating and secretions
  8. Mild sedation to Delirium

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atropine (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
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hyoscyamine (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
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HYOSCYAMINE SULF 0.125 MG TAB Generic $0.14 each