Pharmacokinetic study of 5-fluorouracil in a novel dialysate solution: a long-term intraperitoneal treatment approach for advanced colorectal carcinoma

Five patients with advanced colorectal and gastric carcinoma with peritoneal deposits were treated by continuous weekdays intraperitoneal (i.p.) instillation of 5-fluorouracil (5-FU) 200 mg m-2 day-1 in a novel dialysate solution that ensures maximal exposure of peritoneal areas liable to bear tumours for 24 h. A solution of icodextrin, a glucose polymer, in a 21 twin-bag delivery system allowed a single daily exchange and demonstrated the feasibility of long-term continuous ambulatory treatment with up to 17.4 g of 5-FU, delivered intraperitoneally, in this initial study. During the entire study, there were 235 fluid exchanges or 470 connections and disconnections and no bacterial peritonitis or exit site infection were observed. There was no treatment-associated toxicity worse than WHO grade 2. Drug concentrations in both peritoneal and plasma compartments followed a first-order model with similar half-life value of 1.3 h. 5-FU pharmacokinetic parameters (half-life values, total body clearance, peritoneal clearance and pharmacological advantage of the i.p. route) with this novel icodextrin carrier solution were similar to those obtained in other referenced pharmacokinetic studies with other carrier solutions (dextrose dialysate and lactated Ringer's solutions). This confirms that icodextrin solution is physiologically neutral, drug compatible and allows adequate dwell times with constant fluid balance for long-term continuous intraperitoneal chemotherapy. The pharmacokinetic parameters from this study will be used to design a loading dose infusion schedule in an attempt to maintain steady-state i.p. 5-FU levels in a new multicentre phase I trial.