Drug Case Study: Atropine

Drug Name

Drug Classification

• Anticholinergic / Antimuscarinic Agent
• Parasympatholytic
• Belladonna Alkaloid
• Antidote (for organophosphate/nerve agent poisoning)
• Antiarrhythmic (Class: Vagolytic)
• Diagnostic Agent (ophthalmic preparations)
• Antiparkinsonian (older use)
• Pregnancy Category C

Indications

• Symptomatic sinus bradycardia and bradyarrhythmias
• Preoperative medication to reduce salivary, tracheobronchial, and pharyngeal secretions
• Antidote for organophosphate and nerve agent poisoning (anticholinesterase toxicity)
• Reversal of excessive muscarinic effects of cholinergic drugs (e.g., neostigmine)
• Treatment of peptic ulcer disease and GI spasm (reduces secretions and motility)
• Spastic conditions of the biliary tract
• Cardiac arrest (vagally-induced asystole)
• As part of ACLS protocols for bradycardia

• Mydriasis (pupil dilation) for eye examinations
• Cycloplegia (paralysis of accommodation) for refraction
• Treatment of uveitis and iritis

Mechanism of Action

Dosage

Note: Minimum dose in children is 0.1 mg; paradoxical bradycardia can occur with doses below 0.1 mg.

Route of Administration

• Intravenous (IV) - preferred in emergencies (fastest onset)
• Intramuscular (IM) - used when IV access unavailable (2-6 mg for organophosphate poisoning)
• Subcutaneous (SC)
• Oral (PO)
• Ophthalmic (topical)
• Endotracheal (ET) - via tracheal route in cardiac arrest when IV not available (2-2.5x IV dose)

Contraindications

• Glaucoma (angle-closure) - atropine raises intraocular pressure due to mydriasis and can precipitate acute angle-closure crisis
• Myasthenia gravis - may worsen weakness by blocking residual ACh activity
• Obstructive uropathy / benign prostatic hypertrophy (BPH) - risk of acute urinary retention
• Pyloric stenosis / intestinal atony / paralytic ileus - worsens obstruction
• Tachyarrhythmias - increases heart rate; contraindicated in AF/flutter with rapid ventricular response
• Thyrotoxicosis - risk of exacerbating tachycardia
• Hypersensitivity to atropine or belladonna alkaloids

Important: Atropine carries no FDA black box warning and has no absolute contraindications when used in life-threatening emergencies (e.g., organophosphate poisoning, hemodynamically significant bradycardia). Relative contraindications are routinely overridden. (StatPearls, NCBI Bookshelf)

Side Effects

• Antidote: Physostigmine (a reversible cholinesterase inhibitor that crosses the BBB)

Nursing Responsibilities

Assessment (Before Administration)

• Obtain complete health history including pre-existing conditions: glaucoma, BPH, cardiac arrhythmias, GI obstruction
• Record baseline vital signs: heart rate, blood pressure, respiratory rate, temperature
• Assess current medications for anticholinergic drug interactions
• Review allergy history (especially to belladonna alkaloids)
• Assess pupil size and reaction before ophthalmic use
• Assess bowel sounds and urine output before and after administration
• For cardiac use: attach patient to continuous cardiac monitor; have crash cart/defibrillator accessible

Administration

• IV push: Administer slowly over 1-2 minutes. Slow or diluted IV push can cause paradoxical bradycardia - administer undiluted and briskly for cardiac indications
• Ensure IV patency before administration
• Have emergency equipment (atropine, physostigmine) available when giving high doses
• For ophthalmic use: apply gentle pressure to the lacrimal sac (inner corner of eye) for 1-2 minutes after instillation to minimize systemic absorption
• Ensure minimum pediatric dose of 0.1 mg to avoid paradoxical bradycardia

Monitoring (During and After)

• Monitor heart rate and rhythm continuously (ECG monitoring during IV administration)
• Assess blood pressure every 5-15 minutes
• Monitor urine output - observe for urinary retention (palpate bladder, note last void time)
• Monitor bowel sounds for decreased motility/ileus
• Assess for signs of anticholinergic toxicity: flushing, fever, dry mouth, confusion, tachycardia
• Monitor pupil response and visual changes
• Check temperature frequently - atropine impairs sweating and can cause hyperthermia
• In organophosphate poisoning: reassess secretions, bronchospasm, and pupil size; re-dose until secretions dry

Safety Measures

• Ensure atropine is always stocked in the crash cart, cardiac surgery floor, and OR
• For AtroPen auto-injector: instruct on proper injection technique (outer thigh preferred)
• Document dose, route, time, and patient response accurately
• Keep physostigmine available as antidote in settings of potential overdose

Patient Education

1. Dry Mouth: Suck on sugarless candies or ice chips; rinse mouth frequently with water. Avoid alcohol.
2. Vision Changes: Do not drive or operate heavy machinery - blurred vision and light sensitivity are expected effects of the drug. Wear sunglasses outdoors.
3. Heat Sensitivity: Avoid strenuous activity and hot environments - atropine reduces the ability to sweat, increasing the risk of heat stroke.
4. Bowel and Bladder: Report difficulty urinating or severe constipation to the healthcare provider immediately.
5. Eye Drops (ophthalmic): Effects on vision may last several days. Blink gently after instillation; press the inner corner of the eye to reduce absorption.
6. Report immediately: Rapid or irregular heartbeat, confusion, hallucinations, difficulty urinating, eye pain, or any worsening symptoms.
7. Preoperative use: Expect a dry mouth and possible increase in heart rate - these are expected effects.
8. Avoid other anticholinergics: Do not take antihistamines, antidepressants (TCAs), or antipsychotics without medical advice while on atropine.
9. Auto-injector (AtroPen): Patients at risk for organophosphate exposure (e.g., military, agricultural workers) should be trained on self-injection technique.

Drug Interactions

The majority of drug interactions involve drugs with anticholinergic properties, leading to additive toxicity. Clinicians must perform thorough medication reconciliation. (StatPearls, NCBI Bookshelf)

Conclusion

Bibliography

1. Brunton, L. L., Knollmann, B. C., & Hilal-Dandan, R. (Eds.). (2023). Goodman & Gilman's The Pharmacological Basis of Therapeutics (14th ed.). McGraw-Hill Education.
2. Whalen, K. (Ed.). (2019). Lippincott Illustrated Reviews: Pharmacology (7th ed.). Wolters Kluwer. pp. 175-179.
3. Barash, P. G., Cullen, B. F., Stoelting, R. K., et al. (2022). Barash, Cullen, and Stoelting's Clinical Anesthesia (9th ed.). Wolters Kluwer.
4. Tintinalli, J. E., et al. (2020). Tintinalli's Emergency Medicine: A Comprehensive Study Guide (9th ed.). McGraw-Hill Education.
5. Fishman, A. P., et al. (2023). Fishman's Pulmonary Diseases and Disorders (6th ed.). McGraw-Hill Education.
6. Farzam, K., Kidron, A., & Lakhkar, A. D. (2023). Atropine. In StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. Retrieved from NCBI Bookshelf.
7. RNpedia. (2024). Atropine Sulfate Nursing Considerations & Management. Retrieved from RNpedia.