Atropine injection for life-threatening muscarinic symptoms and bradycardia

Atropine sulfate injection is a sterile solution administered by intravenous, intramuscular, subcutaneous, intraosseous, or endotracheal routes. It temporarily blocks severe or life-threatening muscarinic effects such as excessive salivation, bradycardia, or poisoning by organophosphorus compounds, carbamates, or muscarinic mushrooms.

• Temporary blockade of severe muscarinic effects: Used as an antisialagogue and antivagal agent in preanesthesia and during surgery.
• Antidote for poisoning: Treats organophosphorus, carbamate, or muscarinic mushroom poisoning in adults and children, with doses titrated to symptom response.
• Symptomatic bradycardia: Used to raise heart rate in patients with vagal-induced bradycardia, excluding heart transplant patients and certain types of heart blocks, in both adult and pediatric populations.

Atropine sulfate

Atropine is an antimuscarinic agent that blocks the action of acetylcholine on muscarinic receptors located on smooth muscles, glands, and the heart. By competitively inhibiting these receptors, it reduces vagal stimulation, alleviates muscarinic symptoms such as excessive secretions, and increases heart rate. It has stronger effects on heart, intestines, and bronchial muscle than similar agents but a weaker effect on the eyes and some glands.

General Administration

Inspect the solution for clarity and integrity before use. Discard unused portions within 24 hours after opening. Preferred route is intravenous, but intramuscular, subcutaneous, intraosseous, and endotracheal routes are acceptable.

Adult Dosage

• Antisialagogue and antivagal use: 0.5 to 1 mg IV/IM/SC 30–60 minutes before surgery; repeat every 4–6 hours as needed; maximum total dose 3 mg.
• Poisoning (organophosphorus, carbamate, muscarinic mushroom): 1 to 6 mg IV/IM/ET depending on severity; repeat every 3–5 minutes. Dose may be doubled until response. Maintenance infusion given using 10%–20% of loading dose per hour; no maximum total dose.
• Symptomatic bradycardia: 0.5 mg IV/IM or 1–2 mg diluted ET; repeat every 3–5 minutes as needed; maximum total dose 3 mg.

Pediatric Dosage

• Antisialagogue and antivagal use: 0.02 mg/kg IV/IM/SC 30–60 minutes before surgery; repeat every 4–6 hours. Maximum single dose: <12 years, 0.5 mg; ≥12 years, 1 mg. Maximum total dose: <12 years, 1 mg; ≥12 years, 2 mg.
• Poisoning: 0.02 to 0.06 mg/kg IV/IM/IO/ET every 5 minutes; dose may be doubled until response. Maintenance infusion as 10%–20% of loading dose per hour; no maximum total dose.
• Symptomatic bradycardia: 0.02 mg/kg IV/IO or 0.04 to 0.06 mg/kg ET, followed by saline flush and ventilations; repeat every 5 minutes as needed. Maximum single dose as above.

Dosing in Ischemic Heart Disease

Limit total dose to 0.03 to 0.04 mg/kg to avoid tachycardia and worsening ischemia.

None reported.

• Hypersensitivity: Atropine may cause anaphylaxis.
• Ischemic Heart Disease: Doses should be limited to avoid tachycardia that might worsen cardiac ischemia or infarction size.
• Acute Glaucoma: Atropine can precipitate acute glaucoma.
• Pyloric Obstruction: May convert partial pyloric stenosis to complete obstruction.
• Urinary Retention: May cause complete urinary retention in patients with prostatic hypertrophy.
• Viscid Plugs: Can thicken bronchial secretions in patients with chronic lung disease, leading to plugs.
• Benzyl Alcohol Preservative: Contains benzyl alcohol linked to serious adverse events including "gasping syndrome" in neonates; caution advised in premature or low-birth-weight infants and when combined with other benzyl alcohol-containing products.

Common effects relate to atropine’s antimuscarinic action and include dry mouth, blurred vision, sensitivity to light, tachycardia, constipation, difficulty urinating, and reduced sweating with heat intolerance. Hypersensitivity reactions such as skin rashes may occur. Large or toxic doses can cause central nervous system symptoms such as restlessness, tremor, hallucinations, delirium, and coma, as well as circulatory collapse and respiratory failure.

Atropine sulfate injection decreases the rate (but not extent) of absorption of mexiletine. This delay can be reversed by co-administration of intravenous metoclopramide with atropine.

Pregnancy

Data are insufficient to clearly define risk, but atropine has not been associated with increased birth defects in observational studies. Severe muscarinic events during pregnancy can be life-threatening and treatment with atropine should not be withheld.

Lactation

Trace atropine is present in human milk after oral use; no data exist for intravenous use. To minimize infant exposure, breastfeeding mothers may pump and discard milk for 24 hours after administration before resuming.

Symptoms of overdose include palpitations, dilated pupils, dry skin, thirst, dizziness, restlessness, tremor, hallucinations, delirium, coma, circulatory collapse, and respiratory failure. Pediatric doses over 10 mg may be fatal.

Treatment involves controlling excitement and convulsions with short-acting barbiturates or diazepam. Physostigmine may reverse central effects, but repeated doses may be necessary. Supportive care including artificial respiration and temperature control may be needed. Atropine is not removed by dialysis.

Store as indicated on the packaging. After initial use, discard unused portion within 24 hours.