Serotonin syndrome associated with metaxalone overdose

J Med Toxicol. 2014 Dec;10(4):402-5. doi: 10.1007/s13181-014-0404-5.

Abstract

Introduction: Serotonin syndrome is a potentially life-threatening entity associated with pro-serotonergic medications in therapeutic use, in overdose, or when co-administered with other drugs. A broad range of drugs and drug combinations have been associated with serotonin syndrome. Metaxalone overdose associated with serotonin syndrome has not been previously reported.

Case report: (Case 1) A 23-year-old female overdosed on tramadol and metaxalone. She developed dysautonomia, diaphoresis, lower extremity rigidity and spontaneous clonus, flaccid upper extremities, and hyperthermia 5 h after ingestion. Her course was complicated by status epilepticus. (Case 2) A 56-year-old female overdosed on metaxalone and was found unresponsive. She developed dysautonomia, lower extremity rigidity and spontaneous clonus, flaccid upper extremities, rhabdomyolysis, acute renal failure, and hyperthermia. Non-depolarizing neuromuscular blockade and cooling blankets were required to control hyperthermia in both cases. Serum metaxalone levels were markedly elevated in both cases.

Conclusion: These are the first reported cases of metaxalone overdose associated with serotonin syndrome, which may be related to monoamine oxidase inhibition.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Drug Overdose / complications*
  • Female
  • Humans
  • Middle Aged
  • Neuromuscular Agents / poisoning*
  • Oxazolidinones / poisoning*
  • Serotonin Syndrome / chemically induced*

Substances

  • Neuromuscular Agents
  • Oxazolidinones
  • metaxalone