Evaluation of toxicity after acute accidental methotrexate ingestions in children under 6 years old: a 16-year multi-center review.

CONTEXT: There is little data on the frequency of adverse events following acute methotrexate ingestions in pediatric patients. Likewise, recommendations for observation length, site and management strategies in this population are not well established. Therefore, most recommendations are modeled after management of chronic overdose in patients with underlying medical conditions.

OBJECTIVE: The primary objective of this study is to determine the frequency of acute toxicity after acute methotrexate accidental unsupervised ingestions in patients less than six years. In addition, we describe the frequency of late toxicity and characterize the management site and approaches.

MATERIALS AND METHODS: This is a retrospective cohort study of pediatric accidental unsupervised methotrexate ingestions reported to six poison centers in the United States over a 16 year period. Demographic information, exposure details, signs, symptoms, treatments, length and location of observation and outcomes were collected.

RESULTS: 103 patients met inclusion criteria. Methotrexate dose was reported in 86 patients (84%) and ranged from 1.3 mg-75 mg. The majority of cases (97%) ingested a dose ≤20 mg. The significant majority of cases experienced no clinical effects (99 of 103 cases; 96%). Three children experienced minor outcome (3%). There were no patients with a major outcome or death.

CONCLUSIONS: The incidence of toxicity from pediatric single, acute ingestions of methotrexate is rare and when it occurs is generally limited to no or only minimally concerning effects. Because concentrations from single ingestions were consistent with low subtoxic exposures, we believe that home monitoring without hospital referral and without methotrexate specific therapy is reasonable in those with acute ingestions up to 20 mg.