Hemoperfusion in the Treatment of Doxylamine-Induced Rhabdomyolysis

Introduction: Rhabdomyolysis is characterized by myocyte necrosis and release of intracellular contents into the circulation. It may manifest as myalgia, acute kidney injury (AKI), electrolyte abnormalities, and arrhythmia. Doxylamine succinate is a 1st generation antihistamine, and an active ingredient in many over-the-counter decongestant products. Doxylamine overdose has been reported to cause severe rhabdomyolysis. Cornerstones of management include prompt recognition, adequate hydration, and close monitoring of electrolytes. Literature on drug intoxication have explored the role of hemoperfusion as an adjunct to facilitate rapid clearance of drugs from the circulation. To date, however, the use of hemoperfusion for doxylamine-induced rhabdomyolysis has not been previously reported. Case Description: A 23-year old female presented with decreased sensorium, generalized myalgia, and oliguria five hours after consuming 190 tablets of doxylamine succinate. Her past medical, family, and personal-social histories were non-contributory. On admission, her vital signs were normal and the systemic physical exam was unremarkable. She was lethargic, but without any focal neurologic deficits. Initial laboratory tests showed elevated creatine kinase (CK) levels, azotemia, myoglobinuria, hyperkalemia, hyperphosphatemia, and metabolic acidosis. She was managed as a case of severe rhabdomyolysis complicated by AKI secondary to doxylamine intoxication. Despite aggressive volume expansion and supportive therapy, she remained oliguric with intractable hyperkalemia and metabolic acidosis. Hence, she underwent emergency, combined hemoperfusion (HP) and hemodialysis (HD) on the 1st three hospital days. Serial monitoring of urine output, CK, creatinine, and electrolyte levels on succeeding days showed resolution of the rhabdomyolysis. The patient was eventually weaned off HP-HD and discharged improved on the 7th hospital day. Discussion: Doxylamine overdose is posited to cause rhabdomyolysis through direct myocyte injury. In cases of impaired renal clearance, plasma concentrations of said drug remains elevated for an extended duration, allowing for persistent muscle injury. Due to its lipophilic nature and relatively high molecular weight, systemic clearance of doxylamine in patients with severe AKI can be facilitated by hemoperfusion, leading to faster recovery and shorter length of hospital stay.