Pediatric Cyclic Antidepressant Ingestions: When Is It Safe to Stay Home?

Abstract & Commentary

Source: Spiller HA, et al. Use of dosage as a triage guideline for unintentional cyclic antidepressant (UCA) ingestions in children. Am J Emerg Med 2003;21:422-424.

Cyclic antidepressant (CA) poisoning has significant potential for life-threatening complications, most notably malignant dysrhythmia, obtundation, and seizure. In adults, overdose frequently is intentional and the amount ingested may be unclear. Children often present with unintentional, single-drug ingestions, where pill counts or witnessed events may allow for a firm estimate of the amount ingested. Spiller and colleagues sought to evaluate outcomes relative to amount of CA ingested, using toxicology center data in a case series format.

Children 6 years of age or younger who had ingested an identified amount of CA and for whom there was telephone follow-up that established a known outcome were included; children with polydrug ingestions were excluded. Ingested CA agents included amitriptyline (53%), imipramine (27%), nortriptyline (10%), doxepin (7%), amoxapine (1%), and clomipramine (1%). Mean subject age was 2.4 years (range 7 months to 6 years) among the 246 subjects included in the study. Outcomes generally were benign, as 75% remained asymptomatic (185/246) and another 23% (57/246) were judged to have only minor effects. One hundred thirty-six children (55%) were evaluated in an emergency department (ED), while 110 were monitored in the home. Seventy-one percent (96/136) of those seen in the ED had ingested less than 5 mg/kg of CA; the majority of those were asymptomatic (74/96, 77%), whereas the other 22 had minor symptoms at most. However, nearly two-thirds of the asymptomatic ED group and roughly the same proportion of the minor symptom ED group had been given activated charcoal. Looking at those children managed at home, 22% (24/110) were reported to be drowsy at worst, while the remaining children (78%, 86/110) were asymptomatic.

Using a 5 mg/kg threshold that has some literature support,1 the authors found that 75% (43/57) of patients with minor symptoms reported an ingestion less than 5 mg/kg. Only four patients had ingestions exceeding the 5 mg/kg criterion, with half having a moderate effect and the other half having a major effect outcome. There were no fatalities. The authors concluded that home monitoring might be appropriate in children age 6 years or younger with known unintentional CA ingestions totaling 5 mg/kg or less.

Commentary by Richard A. Harrigan, MD, FAAEM

It would be helpful to have a reliable numerical dividing line with CA ingestions; it could serve as a triage tool for poison centers, much like the 150 mg/kg threshold in acute pediatric acetaminophen ingestions (healthy, non-fasting children). At first pass, I was wary of lumping all these CA agents together under one 5 mg/kg umbrella; unlike acetaminophen, these are different drugs that share chemical structural similarity. However, the agents in this study appear to be of equivalent potencies after reviewing the dosage ranges published in the Physicians’ Desk Reference. While this paper seems to tell us that those patients who ingest less than 5 mg/kg do well, its observational nature by design allowed some patients to receive activated charcoal while others did not. Furthermore, only four patients had moderate or major effects (outcomes that are evidently defined by the Toxic Exposure Surveillance System,2 yet are not defined in the body of the paper), and paradoxically it would be comforting to see more children with serious toxicity—and their mg/kg ingestion calculations—before accepting this threshold. This study really seems to demonstrate that children with CA ingestions who are asymptomatic or exhibit minor symptoms at most generally do well when monitored without aggressive treatment.

Dr. Harrington is Associate Professor of Emergency Medicine, Temple University Hospital and School of Medicine, Philadelphia, PA. 

References

1. McFee RB, et al. Selected tricyclic antidepressant ingestions involving children 6 years old or less. Acad Emerg Med 2001;8:139-144.

2. Litovitz TL, et al. 2001 Annual Report of the American Association of Poison Control Centers Toxic Exposure Surveillance System. Am J Emerg Med 2000;19:337-395.