Reactions Weekly | 2021
Methadone overdose
Abstract
Various toxicities following accidental exposure: case report An 18-month-old girl developed various toxicities, including sedation, miosis, bradypnoea with hypoxic respiratory failure, QTc prolongation and ventricular bigeminy with unifocal premature ventricular contractions following accidental ingestion of (her parent’s) methadone at an overdose. The girl, who had been previously healthy, accidentally consumed up to 140mg of liquid methadone preparation of her parent. She subsequently developed miosis, sedation and notable bradypnoea, with hypoxic respiratory failure. The emergency medical services initially administered intranasal naloxone, resulting in a transient response Hence, the girl received a continuous infusion of naloxone. At 6 and 12 hours post-ingestion, ECG showed ventricular bigeminy with unifocal premature ventricular contractions originating from the right ventricular outflow tract. At 16 hours after ingestion, she experienced three episodes of premature ventricular contractions over a 10-second rhythm strip. Further, her QTc interval peaked at 441 msec. During this period, her magnesium and potassium levels ranged from 2.0–2.5 mg/dL and 4.0–4.57 mmol/L, respectively. While receiving naloxone, she did not experience hypoxia or respiratory depression. After 20 hours of ingestion, her serum methadone level was 164 mg/mL (drug toxicity). Urine analysis detected methadone and its metabolite; no other compounds were found. Her symptoms resolved over 16–24 hours.