CASE REPORT: (Case 1) A 29-year-old woman with overdose of
metaxalone presented to the emergency department with altered mental status, seizure-like activity,
hyperthermia, rigidity in the lower extremities,
myoclonus, and
hyperreflexia. Vital signs on arrival include blood pressure of 168/80 mmHg, heart rate of 208 beats per minute (bpm), respirations of 20/min, a temperature of 41.6° C rectally, and room air oxygen saturation of 97%. She was intubated and sedated with
benzodiazepines, and actively cooled. Serum
paroxetine concentration was 23 (therapeutic range: 20-200) ng/mL, and serum
metaxalone concentration was 31 mcg/mL (peak plasma concentrations average 0.9 mcg/mL at 3.3 h following a single oral dose of 400 mg). (Case 2) A 27-year-old man presented to the emergency department with altered mental status, rigidity in his lower extremities,
myoclonus, and
hyperreflexia. Vital signs on arrival include blood pressure of 158/131 mmHg, heart rate of 126 bpm, respiratory rate of 20 breaths per minute, and temperature of 37.2°C, with oxygen saturation of 98% on room air. His medication list included
metaxalone and
escitalopram. He was managed aggressively with IV boluses of
diazepam, in total 80 mg, in the emergency department. Serum
escitalopram concentration was 24 ng/mL with a therapeutic range of 21-64 ng/mL, and serum
metaxalone concentration was 58 mcg/mL.
CONCLUSION: