Serious Toxicity in an Infant Due to Ingestion of 1 mg Risperidone

• Main Authors: Anderson, K T, Caravati, E M, Seger, C J
• Format: Conference Proceeding
• Language: English
• ISSN: 1556-3650

Background: There is limited experience with acute unintentional risperidone overdose in patients < 6 years of age. We report a case of risperidone ingestion by an infant with confirmed serum levels that resulted in serious toxicity. Case Report: A 6-month-old, 3.9 kg girl with a history of caudal regression syndrome, sacral agenesis, and otitis media was given a 4 oz. bottle that contained 2 mg of risperidone instead of amoxicillin. The child drank 2 oz. (estimated dose 1 mg, 0.5 mg/kg) and within one hour presented to the ED lethargic with miotic pupils. Her vital signs were: heart rate 135 beats/min, blood pressure 90/40 mm Hg, temperature 98.9 F, and respiratory rate 30 breaths/min. Six hours after presentation her blood pressure decreased to 54/41 mm Hg, which increased to 90/48 mm Hg after a fluid bolus (20 ml/kg, NS). During this time she was listless with intermittent stiffening and shaking of extremities. EKG revealed sinus tachycardia (169 beats/min), QRS interval 60 ms and a prolonged QTc of 462 ms. A serum risperidone concentration obtained 7 hours post-ingestion was 13 ng/ml and active metabolite 9-nydroxyrisperidone was 158 ng/ml. 24 hours after presentation, she was alert, interactive with no muscle rigidity but continued to have constricted pupils. Case Discussion: Our patient demonstrated miosis, lethargy, hypotension, muscle rigidity, and prolonged QTc after ingestion of a borderline referral dose of risperdone according to the AAPCC atypical antipsychotic management guideline (>1mg). This is the first documented risperidone serum concentration after a pediatric ingestion and is consistent with the reported dose. Conclusion: This case demon-states the potential for moderate to severe risperidone toxicity in infants near the guideline referral dose.