Hatim A. Hassan M.D.              ST. LOUIS UNIVERSITY  
Successful treatment of normeperidine neurotoxicity by hemodialysis   
         
 

Meperidine (demerol) is a potent widely used narcotic analgesic. Normeperidine, its major metabolite, is half as potent as an analgesic but 2-3 times more potent as a convulsant. The plasma half-life of normeperidine increased from 12-21 hrs in normal individuals to 35 hrs in those with significant renal impairment. Thus, normeperidine may significantly accumulate in patients with renal failure, and lead to serious complications. The intensity of the central nervous system (CNS) excitation is highly correlated with the plasma concentration of normeperidine. Moreover, normeperidine CNS toxicity is not reversed by naloxone which may, in fact, exacerbate it. We report a 72-year-old white female with end stage renal disease on peritoneal dialysis, and history of severe peripheral vascular disease, who had been receiving large doses of meperidine for pain control. The patient subsequently developed myoclonic contractions and a grand mal seizure. The patient was successfully treated with hemodialysis (F 8 dialyzer) for presumed normeperidine-induced CNS toxicity. During HD, normeperidine plasma clearance was 50 ml/min, percentage plasma extraction was 24%, and there ws 26% reduction in its plasma concentration over 3 hours of HD (average of measurements performed at times 0,1.5 and 3 hrs on HD). With approximate plasma clearance of 50 ml/min, about 2.4 mg of Normeperidine has been removed during the 4 hours of HD. This amount was greater than the normeperidine distributed in the extracellular fluid (ECF – 1.8 mg), and about half of the amount distributed in total body water (TBW – 5.2 mg), which in either case seems to be significant.

Conclusion: Our findings suggest that HD may be utilized effectively for treating patients with normeperidine-induced neurotoxicity. This is the first report of normeperidine neurotoxicity to be successfully reversed with HD.