Atropine

# Atropine ## Overview - **Classification**: Anticholinergic, Muscarinic Antagonist - **Mechanism**: Blocks acetylcholine's action at muscarinic receptors, leading to parasympathetic inhibition. This increases heart rate, reduces secretions, and relaxes smooth muscle. ## Primary Indications 1. **Symptomatic Bradycardia** - Increases heart rate in hemodynamically unstable bradycardia. 2. **Organophosphate or Carbamate Poisoning** - Antidote to muscarinic effects. 3. **Preoperative Medication** - Reduces salivary and bronchial secretions, prevents bradycardia during intubation. 4. **Cholinergic Crisis/Reversal** - Reverses muscarinic effects of cholinesterase inhibitors. ## Adult Dosing ### Standard Dosing **Symptomatic Bradycardia** - **Dose**: **0.5 mg** - **Frequency**: Every 3-5 minutes as needed - **Route**: Intravenous (IV), Intraosseous (IO) - **Maximum Dose**: Total of **3 mg** (or 0.04 mg/kg) **Organophosphate/Carbamate Poisoning** - **Dose**: **1-2 mg** (or higher for severe cases) - **Frequency**: Every 5-10 minutes until atropinization (dry mucous membranes, clear lungs, heart rate >80 bpm) - **Route**: Intravenous (IV), Intramuscular (IM) **Preoperative Medication** - **Dose**: **0.4-0.6 mg** - **Frequency**: Single dose - **Route**: Intravenous (IV) or Intramuscular (IM) - **Special Considerations**: Administer 30-60 minutes prior to procedure. **Cholinergic Crisis / Reversal of Neuromuscular Blockade** - **Dose**: **0.6-1.2 mg** (often given with neostigmine/pyridostigmine) - **Frequency**: Single dose or repeated as needed - **Route**: Intravenous (IV) ### Dose Adjustments - **Renal Impairment**: No specific dose adjustments formally recommended for acute use. Use with caution as renally excreted. - **Hepatic Impairment**: No specific dose adjustments formally recommended. - **Elderly Patients**: Increased sensitivity to anticholinergic effects. Start with lower doses and titrate carefully, monitor for confusion, urinary retention. ## Pediatric Dosing ### Neonates (0-28 days) - **Symptomatic Bradycardia**: **0.02 mg/kg** IV/IO - **Frequency**: Single dose, may repeat once. - **Minimum Dose**: **0.1 mg** (to avoid paradoxical bradycardia). - **Maximum Single Dose**: **0.5 mg**. - **Special Notes**: Use extreme caution due to unpredictable response and risk of paradoxical bradycardia at low doses. ### Infants (1-12 months) - **Symptomatic Bradycardia**: **0.02 mg/kg** IV/IO - **Frequency**: Every 3-5 minutes as needed. - **Minimum Dose**: **0.1 mg** (to avoid paradoxical bradycardia). - **Maximum Single Dose**: **0.5 mg**. - **Maximum Total Dose**: **1 mg**. ### Children (1-12 years) - **Symptomatic Bradycardia**: **0.02 mg/kg** IV/IO - **Frequency**: Every 3-5 minutes as needed. - **Minimum Dose**: **0.1 mg**. - **Maximum Single Dose**: **0.5 mg**. - **Maximum Total Dose**: **1 mg**. ### Adolescents (13-18 years) - **Dose**: Approach adult dosing (e.g., **0.5 mg** IV for bradycardia). - **Frequency**: Every 3-5 minutes as needed. - **Maximum Single Dose**: **1 mg**. - **Maximum Total Dose**: **3 mg**. ## Safety Information ### Contraindications - **Absolute**: Acute narrow-angle glaucoma. - **Absolute**: Obstructive uropathy (e.g., prostatic hypertrophy, bladder neck obstruction). - **Absolute**: Paralytic ileus, severe ulcerative colitis, toxic megacolon. - **Relative**: Myasthenia gravis (may exacerbate weakness), severe cardiac disease (e.g., unstable angina, acute MI). ### Common Adverse Effects - **Very Common (>10%)**: Dry mouth, blurred vision, mydriasis. - **Common (1-10%)**: Tachycardia, palpitations, urinary retention, constipation, headache, dizziness, flushing. - **Serious but Rare**: Ventricular fibrillation, delirium, coma, acute glaucoma, severe allergic reaction. ### Key Drug Interactions - **Anticholinergic Agents**: Increased risk of severe anticholinergic effects (e.g., TCAs, antihistamines, phenothiazines). Monitor for altered mental status, urinary retention. - **Digoxin**: May increase digoxin levels by slowing GI motility. Monitor digoxin levels. - **Potassium Chloride (solid formulations)**: Increased risk of GI lesions due to delayed gastric emptying. Administer with caution. ## Monitoring & Follow-up - **Before Treatment**: Baseline vital signs (HR, BP, respiratory rate), ECG (for bradycardia). - **During Treatment**: Continuous cardiac monitoring, vital signs, level of consciousness, urinary output, assessment for signs of atropinization (organophosphate poisoning). - **Clinical Signs**: Watch for improvement in heart rate/perfusion (bradycardia), drying of secretions, improved breathing (poisoning). ## Clinical Pearls - 💡 **Timing**: Rapid IV push is crucial for effective treatment of symptomatic bradycardia. - 💡 **Pediatric Dosing**: Always ensure the **minimum dose of 0.1 mg** is given in children to prevent paradoxical bradycardia. - 💡 **Organophosphate Poisoning**: Titrate to effect (atropinization) rather than a fixed dose. End-points include clear lungs, dry secretions, and HR >80 bpm. - 💡 **Anticholinergic Syndrome**: Be aware of the "red as a beet, dry as a bone, hot as a hare, blind as a bat, mad as a hatter, full as a flask" mnemonic for severe anticholinergic toxicity. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.