Rhabdomyolysis and acute renal failure following an overdose of doxepine and nitrazepam

Abstract

A 50-year-old woman developed rhabdomyolysis and myoglobinuric renal impairment after an oral dose of 250 mg nitrazepam and 1,250 mg doxepin. Serum creatinine increased from 70 mumol/l to 472 mumol/l in two days. Serum creatine phosphokinase reached a maximal level of 391 mu kat/l (reference range less than 2.5 mu kat/l) on the third day and serum myoglobin was maximally 910 nmol/l (reference range less than 4.5 nmol/l) on the fourth day after the overdose. Passive and active movements of the knees and ankles became increasingly restricted, but the patient felt no muscle pain. Diuresis decreased to 20-22 ml/hour in spite of repetitive doses of furosemide, but was enforced to greater than 100 ml/hour by vigorous infusion of saline. Haemodialysis was avoided on this regimen. It is suggested that in patients intoxicated with nitrazepam and/or doxepin, rhabdomyolysis should be suspected when a rapidly increasing serum concentration of creatinine is found, even in the absence of muscle pain.