A Case of Unintentional Methadone Overdose Followed by Hypoglycaemia

Abstract

Methadone overdose is expected to result in intoxication simulating the other opioids. We report a case of hypoglycaemia following accidental methadone ingestion. A 21-year-old woman presented to a local accident and emergency department 10 hours after ingestion of 800 mg of methadone. She was found to have coma, respiratory suppression, hypotension, prolonged QTc and hypoglycaemia. The hypoglycaemia was reversed by dextrose replacement. The patient required intubation and inotropic support because of cardio-respiratory instability. She eventually recovered without consequence. To date, this is the first reported case of methadone overdose induced hypoglycaemia.

A case report of methadone-associated hypoglycemia in an 11-month-old male

“…Methadone can elicit hypoglycemia during rapid dose escalation or in the case of acute, unintentional exposure, but to date no mechanism has been elucidated. [4–7]…”

Insulinoma mimic: methadone-induced hypoglycaemia

“…There are two retrospective studies20 23 and eight case reports of hypoglycaemia in the setting of methadone use 14–19 21 22. The lowest reported glucose level was 0.6 mmol/L (10 mg/dL),22 with a median of 2.2 mmol/L (40 mg/dL) and range between 0.6 mmol/L (10 mg/dL) and 2.4 mmol/L (44 mg/dL).…”

“…There are two retrospective studies20 23 and eight case reports of hypoglycaemia in the setting of methadone use 14–19 21 22. The lowest reported glucose level was 0.6 mmol/L (10 mg/dL),22 with a median of 2.2 mmol/L (40 mg/dL) and range between 0.6 mmol/L (10 mg/dL) and 2.4 mmol/L (44 mg/dL). Hypoglycaemia occurred during fasting states14–17 and were precipitated by methadone overdose,14 21 22 dose escalation17–20 and/or renal failure 15 17.…”

“…Fung et al presented a similar case of an otherwise healthy woman in her 20s who presented with altered mental status following the ingestion of 800 mg of methadone and was found to have hypoglycaemia with a blood glucose of 0.6 mmol/L (10 mg/dL). 22 Masharani et al outline the case of a woman in her late 30s with obesity, stage 3 CKD (eGFR 30-60) and back pain on methadone 160 mg every 6 hours as needed who presented with Whipple's triad. 17 She had endogenous hyperinsulinaemia (insulin of 8.5 µU/mL, C peptide of 2.7 ng/mL, proinsulin of 49 pmol/L and BHB of 0.15 mmol/L) with a serum glucose level of 2.4 mmol/L (44 mg/dL).…”

“…In mouse models, methadone significantly lowered blood glucose in a dose-dependent manner at doses greater than 10 mg/kg 13. Clinical observations of methadone-induced hypoglycaemia have been documented in retrospective studies and case reports12 14–23 and occurred in situations of overdose when methadone doses were escalated 19 20 24. A retrospective study of the Food and Drug Administration Adverse Event Reporting System from 2004 to 2012 showed significantly increased odds of hypoglycaemia in tramadol and methadone compared with the use of other opioids, such as codeine, hydrocodone, oxycodone, hydromorphone, morphine and fentanyl 12 25…”