eMedicine Specialties > Emergency Medicine > Toxicology

Toxicity, Cyclic Antidepressants: Follow-up

Author: Vivian Tsai, MD, MPH, Assistant Professor at Mount Sinai School of Medicine, Queens Hospital Center
Coauthor(s): Mark A Silverberg, MD, FACEP, MMB, Assistant Professor, Assistant Residency Director, Department of Emergency Medicine, State University of New York Downstate College of Medicine; Consulting Staff, Department of Emergency Medicine, Staten Island University Hospital, Kings County Hospital, University Hospital, State University of New York Downstate at Brooklyn; Mark Biittner, MD, Consulting Staff, Department of Emergency Medicine, Sutter Roseville Medical Center; Daniel M Joyce, MD, Consulting Staff, Department of Emergency Medicine, Saint Vincent's and Saint Mary's Medical
Contributor Information and Disclosures

Updated: Nov 3, 2009

Follow-up

Further Inpatient Care

  • Level of conscious and ECG changes at presentation are the most sensitive clinical predictors of serious complications.
  • Cyclic antidepressant (CA) toxicity typically lasts 24-48 hours following a significant overdose. However, studies have reported prolonged CA toxicity as long as 4-5 days.14 Amitriptyline is the drug most commonly implicated in these cases.
  • Consider ICU admission for any ECG changes.
  • Admission to a monitored bed is appropriate for patients exhibiting only anticholinergic symptoms and no cardiac manifestations.

Complications

  • Seizures
  • Dysrhythmias

Miscellaneous

Medicolegal Pitfalls

  • The use of physostigmine in cyclic antidepressant (CA) poisoning has been associated with complete heart block, asystole, and hypotension.
  • Ipecac syrup is not recommended as the procedure in GI decontamination because of the possibility that patients experience sudden neurologic deterioration (eg, lethargy, seizures) and aspirate.
  • The use of type IA and IC antidysrhythmics or other sodium channel blockade agents may exacerbate toxic effects of CAs on the myocardium.
  • The use of flumazenil for reversal of benzodiazepines overdose with concomitant CAs exposure can precipitate seizures.

Special Concerns

  • ECG is a highly sensitive tool and can be used to rule out CA toxicity. However, it is not specific enough to be used alone to diagnose CA overdose. Widening of QRS complex can be used as a rough guide in determining the prognosis of TCA poisoning (eg, seizures, dysrhythmias). However, characteristic ECG changes in addition to clinical presentation (anticholinergic toxidrome, seizures, hypotension, tachycardia) seen with CAs can be an adjunction in diagnosing CA toxicity.
  • Lidocaine, when used to treat ventricular arrhythmia, should be administered with caution to avoid precipitating seizures.
  • Ventricular bradyarrhythmias, due to depressed atrioventricular conduction and automaticity, can be treated by placement of a temporary pacemaker; alternatively, consider the use of a chronotropic agent.
  • CA exposure in children is common. The potentially lethal dose (with desipramine, imipramine, or amitriptyline) is as low as 15 mg/kg. Toddlers can exceed this threshold with only 1-2 pills and should be evaluated in the emergency department.15
 


More on Toxicity, Cyclic Antidepressants

Overview: Toxicity, Cyclic Antidepressants
Differential Diagnoses & Workup: Toxicity, Cyclic Antidepressants
Treatment & Medication: Toxicity, Cyclic Antidepressants
Follow-up: Toxicity, Cyclic Antidepressants
References
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References

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  3. Melanson SE, Lewandrowski EL, Griggs DA, Flood JG. Interpreting tricyclic antidepressant measurements in urine in an emergency department setting: comparison of two qualitative point-of-care urine tricyclic antidepressant drug immunoassays with quantitative serum chromatographic analysis. J Anal Toxicol. Jun 2007;31(5):270-5. [Medline].

  4. Liebelt EL, Francis PD, Woolf AD. ECG lead aVR versus QRS interval in predicting seizures and arrhythmias in acute tricyclic antidepressant toxicity. Ann Emerg Med. Aug 1995;26(2):195-201. [Medline].

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Further Reading

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Keywords

tricyclic antidepressants, TCAs, CAs, cyclic antidepressant toxicity, cyclic antidepressant overdose, Brugada syndrome, cyclic antidepressants, cyclic antidepressant poisoning, tricyclic antidepressant poisoning, tricyclic antidepressant overdose, cyclic antidepressant overdose, TCA overdose, CA overdose, amitriptyline, doxepin, nortriptyline, TCA poisoning, CA poisoning

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Contributor Information and Disclosures

Author

Vivian Tsai, MD, MPH, Assistant Professor at Mount Sinai School of Medicine, Queens Hospital Center
Vivian Tsai, MD, MPH is a member of the following medical societies: Alpha Omega Alpha and Phi Beta Kappa
Disclosure: Nothing to disclose.

Coauthor(s)

Mark A Silverberg, MD, FACEP, MMB, Assistant Professor, Assistant Residency Director, Department of Emergency Medicine, State University of New York Downstate College of Medicine; Consulting Staff, Department of Emergency Medicine, Staten Island University Hospital, Kings County Hospital, University Hospital, State University of New York Downstate at Brooklyn
Mark A Silverberg, MD, FACEP, MMB is a member of the following medical societies: American College of Emergency Physicians, American Medical Association, Council of Emergency Medicine Residency Directors, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Mark Biittner, MD, Consulting Staff, Department of Emergency Medicine, Sutter Roseville Medical Center
Mark Biittner, MD is a member of the following medical societies: American College of Emergency Physicians
Disclosure: Nothing to disclose.

Daniel M Joyce, MD, Consulting Staff, Department of Emergency Medicine, Saint Vincent's and Saint Mary's Medical
Daniel M Joyce, MD is a member of the following medical societies: American College of Emergency Physicians and American Medical Association
Disclosure: Nothing to disclose.

Medical Editor

Miguel C Fernández, MD, FAAEM, FACEP, FACMT, FACCT, Associate Clinical Professor; Medical and Managing Director, South Texas Poison Center, Department of Surgery/Emergency Medicine and Toxicology, University of Texas Health Science Center at San Antonio
Miguel C Fernández, MD, FAAEM, FACEP, FACMT, FACCT is a member of the following medical societies: American Academy of Emergency Medicine, American College of Clinical Toxicologists, American College of Emergency Physicians, American College of Medical Toxicology, American College of Occupational and Environmental Medicine, Society for Academic Emergency Medicine, and Texas Medical Association
Disclosure: Nothing to disclose.

Pharmacy Editor

John T VanDeVoort, PharmD, Regional Director of Pharmacy, Sacred Heart & St. Joseph's Hospitals
John T VanDeVoort, PharmD is a member of the following medical societies: American Society of Health-System Pharmacists
Disclosure: Nothing to disclose.

Managing Editor

John G Benitez, MD, MPH, FACMT, FACPM, FAAEM, Associate Professor, Department of Medicine, Clinical Pharmacology Division, Vanderbilt University; Managing Director, Tennessee Poison Center
John G Benitez, MD, MPH, FACMT, FACPM, FAAEM is a member of the following medical societies: American Academy of Emergency Medicine, American College of Medical Toxicology, American College of Preventive Medicine, Society for Academic Emergency Medicine, Undersea and Hyperbaric Medical Society, and Wilderness Medical Society
Disclosure: Nothing to disclose.

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Asim Tarabar, MD, Assistant Professor, Director, Medical Toxicology, Department of Emergency Medicine, Yale University School of Medicine; Consulting Staff, Department of Emergency Medicine, Yale-New Haven Hospital
Disclosure: Nothing to disclose.

 
 
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