Atropine
Key Points
- Atropine is a muscarinic antagonist (anticholinergic) with dose-dependent effects.
- Small doses inhibit secretions; moderate doses increase heart rate; large doses decrease GI and urinary motility.
- Primary indications include symptomatic bradycardia, preoperative secretion reduction, and organophosphate/mushroom poisoning.
- Classic anticholinergic side effects remembered by the mnemonic: red as a beet, dry as a bone, blind as a bat, mad as a hatter.
Mechanism of Action
Atropine competitively blocks acetylcholine at muscarinic receptors in the parasympathetic nervous system. Effects are dose-related: small doses inhibit salivary and bronchial secretions and sweating; moderate doses dilate the pupil, inhibit accommodation, and increase heart rate (vagolytic effect); large doses decrease GI and urinary tract motility; very large doses inhibit gastric acid secretion.
Indications
- Symptomatic bradycardia (ACLS protocol).
- Preoperative reduction of salivary and bronchial secretions.
- Muscarinic poisoning symptoms from organophosphate or carbamate insecticide exposure.
- Mushroom poisoning with muscarinic symptoms.
Nursing Considerations
- Use with caution in elderly clients who may react with increased agitation or drowsiness.
- Monitor heart rate closely when used for bradycardia; assess for overcorrection to tachycardia.
- Heatstroke risk increases in high-temperature environments because atropine inhibits sweating.
- Males with benign prostatic hypertrophy (BPH) are at increased risk for urinary retention.
- Physostigmine may be used to reverse severe anticholinergic toxicity.
- Immediately report overdose symptoms: urinary retention, abnormal heartbeat, dizziness, syncope, difficulty breathing, weakness, or tremors.
Side Effects and Adverse Effects
- Common: Dry mouth, blurred vision, increased heart rate, flushed skin, constipation, urinary retention.
- CNS: Agitation, drowsiness, delirium (especially in elderly).
- Serious: Heatstroke in high temperatures, severe tachycardia, complete urinary retention.
Health Teaching
- Medications may cause dizziness and drowsiness; use caution with activities requiring alertness.
- Frequent oral hygiene helps manage dry mouth.
- Avoid high-temperature environments; stay well hydrated.
- Report difficulty urinating, rapid heartbeat, or confusion immediately.
Related Concepts
- anticholinergics - Broader anticholinergic drug class context.
- Bradycardia - Primary cardiac indication for atropine use.
- epinephrine - Co-administered in cardiac emergency contexts (ACLS).
Self-Check
- How do atropine effects change with increasing dose?
- Why is atropine contraindicated or used cautiously in high-temperature environments?
- What reversal agent can counteract severe anticholinergic toxicity?