Zidovudine (AZT) overdose in a healthy newborn receiving postnatal prophylaxis.

CONTEXT: Pediatric medication dosing and administration, faced with inherent challenges of dose to body weight adjustment and variable delivery vehicles, may lead to inadvertent errors effectively resulting in overdose. Zidovudine (AZT), a nucleoside analog reverse transcriptase inhibitor (NRTI), is a commonly prescribed medication to treat HIV-exposed newborns, with limited overdose data in this patient population. Metabolic acidosis with elevated lactate is the most serious consequence of AZT toxicity in the adult population, associated with mortality. Other significant effects may include neutropenia and hepatic dysfunction. CASE REPORT: A 4-day-old male infant who received two inadvertent 10-fold overdoses of AZT while being treated for HIV postnatal prophylaxis. The newborn developed a transient metabolic acidosis with elevated lactate that resolved within 24 h, a small increase in AST, and persistent neutropenia for 5 weeks. The patient's mother cited several key factors leading to the dosing error. DISCUSSION: The paucity of AZT overdose data in newborns and infants compels this case report, which reviews the published literature and provides insight into prevention and improvement of pediatric patient safety.