Possible Delay in Symptomatology of a Methadone Overdose in a Patient Ingesting an Energy Drink and Dextroamphetamine/Amphetamine.

Introduction: Methadone is a mu-opioid agonist with a delayed time to peak concentration that requires an extended period of monitoring following an overdose. Available data suggests that the combination of psychostimulants with methadone may augment antinociception and tolerance to opioids. Case Report: A 26-year-old male (83.9 kg) presented to the ED approximately 1 hour after unintentionally ingesting 200-250 mg of liquid methadone and an energy drink, along with 20 mg of dextroamphetamine/amphetamine prior to the event. Vital signs were: blood pressure (BP), 143/91 mmHg; heart rate (HR), 74; respirations (RR), 16; oxygen saturation 95% on room air. His urine drug screen was positive for amphetamines and methadone. Patient was monitored for 4 hours with no change in status and was discharged home. Approximately 26 hours later patient was found cyanotic and apneic. Patient was given 2 mg of naloxone and awoke with normal mental status. On presentation the patient's vital signs were: BP, 114/70 mmHg; HR, 114; RR 16; oxygen saturation 94% on 3 liters nasal cannula. During his ED stay, he required 2 doses of naloxone secondary to oxygen desaturation and was admitted to the hospital. His repeat urine drug screen was positive for amphetamines and methadone. The patient was discharged the following day. Discussion: This case illustrates an unintentional methadone overdose combined with the intentional ingestion of an energy drink and dextroamphetamine/amphetamine that possibly masked the toxicity for over 24 hrs. Monitoring parameters for methadone overdoses may need re-evaluation in the setting of the co-ingestion of a stimulant.