A Retrospective Study of Fluoxetine Unintentional Ingestions: Establishing a Toxic Dose in the Pediatric Population

Background: Little published data exists on the effects of pediatric fluoxetine unintentional exposures. Case-based dose recommendations (mg/kg) or clinical effect probabilities to aid poison center decision making options are lacking. We used National Poison Data System (NPDS) case data to study this problem. Methods: Unintentional pediatric (age less than or equal to 6 yr) fluoxetine single ingestion cases reported to NPDS from 2002-2006 were reviewed. Medical outcome (MO) versus dose history (mg/kg) was examined using ordinal logistic regression (SAS JMP 6.0). "Taste or lick" exposures were assigned a dose history of 1/10 of the dosage form involved. Weight for cases that did not report a weight was calculated based on a quadratic estimate of weight for age from cases with a weight. Results were considered statistically significant if p < 0.05. Results: The search query retrieved 4975 cases. Dose history, age, and follow-up to a known medical outcome were available for 2015. MO for the 2015 was: No Effect in 90.67%, Minor in 8.59%, Moderate in 0.74%, and no Major or Death. The mean [min, max] age was 26 [0.33, 72] months and 52% were male. The mean historical dose was 42 [0.2, 2500] mg or 3.1 [0.02, 172] mg/kg. Clinical effects were absent in 1827 of 2015 (91%) of the cases. Clinical effects in all 4975 cases included: nausea/vomiting (144), drowsiness/lethargy (130), agitation/irritable (65), cardiovascular (21), mydriasis (7), seizure/s (4), and diaphoresis (1). The table shows representative ordinal logistic regression results (p=0.0402). Discussion: There were no deaths or major outcomes in 4975 exposures. Of the 2015 cases with dose histories, only 188 cases resulted in any adverse outcome. Conclusion: MO was related to historical dose. The probability of No Effect ranged from 95% (at 10 mcg/kg) to 85% (at 100mg/kg). Pediatric single substance fluoxetine ingestions are unlikely to produce symptoms.