Haemodialysis in imipramine poisoning? An experimental study

In the last several years an increasing number of severe imipramine intoxications have been observed. Though standard principles for the treatment of acute tricyclic poisoning have been established, nonetheless there still exists doubt on the most effective method of tricyclic removal in cases of massive overdose. Haemodialysis was successfully employed until now but has not found general acceptance as only insignificant amounts of imipramine could be recovered from the dialysate. An experimental clearance study was undertaken using radiolabelled imipramine (14C-I) to obtain insight into the usefullness of haemodialysis in imipramine poisoning. 14C-I clearances which were calculated in a closed circuit dialysis system ranged between 18 ml/min and 48 ml/min depending on the constitution of the dialysate, i.e. aqueous or lipid solution. Surprisingly a rapid and significant uptake of imipramine by the plastic material (polyvinylchloride) of the extracorporeal blood line system was detected. This escape of imipramine from the blood into the tubings explains the poor recovery of tricyclics from the dialysate, which discredited haemodialysis as a therapeutical method in imipramine poisoning. The results of our experiments may offer a new method of rapid tricyclic elimination in severe imipramine intoxications.