Resin hemoperfusion in ethychlorvynol overdose.

An 18-yr-old male with a severe ethchlorvynol (ECV) overdose was treated with Amberlite XAD-4 resin hemoperfusion. Plasma ECV concentration declined 33% during a 3.5-hr hemoperfusion, but rebounded substantially, peaking 6 hr later. It was estimated that 16% of ECV in the body was removed. Following hemoperfusion, plasma ECV concentrations declined linearly at a rate of 13 mg/1/day. Hemoperfusion clearance was estimated by both the traditional method, using extraction ratios across the column and column blood flow (Cl = 270 ml/min), and an alternative method, using blood concentrations during hemoperfusion and recovery of drug from the resin (Cl = 184 ml/min). The latter may provide a better estimate of hemoperfusion clearance because it is not subject to error (which can be substantial) in measurement of column blood flow. The resin completely extracted ECV from plasma, resulting in a rate of elimination 10 times that expected from endogenous processes. To aid in kinetic analysis, blood:plasma partition and protein binding of ECV in 3 normal subjects were also examined. Blood:plasma ratio averaged 0.88 +/- 0.04 and fraction free in plasma, 0.38 +/- 0.02; neither changed as a function of blood concentration between 27 and 108 mg/1. Our data indicate that removal of ECV from the overdosed patient by hemoperfusion is limited by extensive distribution in and slow redistribution from body tissues, but because of the extremely slow rate of removal by the body and the severe nature of the ECV overdose, Amberlite XAD-4 hemoperfusion may be clinically useful.