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# **Atropine**
## Overview
Atropine is an anticholinergic medication that blocks the action of acetylcholine at muscarinic receptors. It is a competitive antagonist of muscarinic receptors and can reverse the effects of organophosphates and carbamate pesticides.
## Primary Indications
* Bradycardia
* Organophosphate and carbamate poisoning
* Antidote for anticholinesterase agents (e.g., neostigmine, pyridostigmine)
* Preanesthetic medication to reduce secretions
## Adult Dosing
* **Bradycardia:** 0.5 mg intravenously every 3-5 minutes. Maximum total dose typically 3 mg.
* **Organophosphate/Carbamate Poisoning:** 1-5 mg intravenously every 5-15 minutes until signs of atropinization appear (e.g., dry mouth, mydriasis, tachycardia). Higher doses may be required.
* **Preanesthetic Medication:** 0.4-0.6 mg subcutaneously or intravenously 30-60 minutes before induction.
## Pediatric Dosing
* **Bradycardia:** 0.02 mg/kg intravenously or intraosseously, with a minimum dose of 0.1 mg and a maximum dose of 0.5 mg per dose. Repeat every 3-5 minutes up to a maximum of 4 doses or a total dose of 1 mg.
* **Organophosphate/Carbamate Poisoning:** 0.05 mg/kg intravenously every 5-10 minutes until signs of atropinization appear.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment is typically recommended, but caution may be warranted.
* **Hepatic Impairment:** No specific dose adjustment is typically recommended, but caution may be warranted.
## Contraindications
* Tachycardia
* Angle-closure glaucoma
* Hypersensitivity to atropine
* Myasthenia gravis (unless being treated for organophosphate poisoning)
* Certain cardiac conditions (e.g., unstable cardiovascular status, myocardial ischemia)
## Adverse Effects
Common adverse effects include dry mouth, blurred vision, photophobia, dry skin, urinary retention, constipation, tachycardia, and confusion. Less common but serious effects include delirium, hallucinations, arrhythmias, and severe hypersensitivity reactions.
## Key Drug Interactions
* **Anticholinergic agents:** Additive anticholinergic effects.
* **Prokinetic agents (e.g., metoclopramide):** May reduce efficacy.
* **Beta-blockers:** Risk of severe tachycardia.
* **Verapamil:** Risk of severe bradycardia or heart block.
* **Physostigmine:** Used as an antidote for atropine toxicity, but can also antagonize atropine's therapeutic effects.
## Monitoring
* Heart rate and rhythm
* Blood pressure
* Mental status
* Signs of atropinization (e.g., dry mouth, pupil dilation)
* Urine output
## Clinical Pearls
* In organophosphate poisoning, atropine's goal is to block muscarinic effects; it does *not* reverse nicotinic effects (neuromuscular blockade). Pralidoxime is needed for nicotinic effects.
* Doses are often given every 3-5 minutes for bradycardia until a response is seen or the maximum dose is reached.
* Ensure adequate hydration and bladder emptying due to risk of urinary retention.
* Be aware of paradoxical bradycardia at very low doses, although this is rare.
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*Disclaimer: This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and clinical guidelines for complete details and to verify dosages and safety information.*
