[Pharmacokinetics of phenytoin in continuous ambulatory peritoneal dialysis. 2 cases and brief review of the literature].

The pharmacokinetics of phenytoin are studied in 2 patients on CAPD treatment. Free and protein bound phenytoin are lost in the dialysate. The peritoneal clearance of phenytoin varies from 1.6 to 2.4 ml/min. The peritoneal mass transfer varies from 0.022 to 0.059 mumol/min, depending on the phenytoin dose given. The dialysate concentrations of phenytoin reach 40% of the serum levels. Peritoneal losses of phenytoin may be 5% of the daily intake. The clinical significance of serum level measurements in monitoring of phenytoin therapy is discussed. Beside clinical symptoms, the serum free phenytoin level is of most importance. In uremic patients the albumin-bound fraction of phenytoin is reduced.