Pharmacokinetic changes induced by the volume of chemotherapy solution in patients treated with hyperthermic intraperitoneal mitomycin C

Background: The rationale supporting the use of intraperitoneal chemotherapy in peritoneal surface malignancy relates to a large local–regional effect and low systemic toxicity. While optimizing the use of this treatment strategy, little information regarding the effect of volume of chemotherapy solution is available. Objective: The goal of this study was to provide data regarding the effect of volume of chemotherapy solution on the pharmacokinetics of intraperitoneal chemotherapy. Data by which to optimally adjust this parameter during intraperitoneal chemotherapy treatments were sought. Methods: Forty-eight patients with peritoneal surface malignancy were treated with hyperthermic intraperitoneal mitomycin C chemotherapy after a complete cytoreduction to remove all visible evidence of mucinous tumor. The dose of mitomycin C was always 12.5 mg/m² in males and 10 mg/m² in females. The first 12 patients were treated with 6 l of 1.5% dextrose peritoneal dialysis solution. The next 14 patients were treated with 4 l of fluid and then ten patients were treated with 2 l. In the last 12 patients the volume of fluid was 1.5 l/m² . Blood, peritoneal fluid, and urine samples were obtained every 15 min for 90 min; additional blood and urine samples were obtained at 120 min. Mitomycin C concentrations, urine volumes, and final intraperitoneal fluid volume were obtained. Results: The intraperitoneal and the plasma concentrations were highest in the 2-l group, less in the 4-l group, and least in the 6-l group. All differences were statistically significant. Also, the percent of mitomycin C absorbed decreased significantly from 2, to 4, to 6 l of fluid. The area under the curve (AUC) ratio of intraperitoneal concentration times time to intravenous concentration times time was 27.01±4.92 for 2 l, 22.22±7.95 for 4 l, and 24.01±8.46 for 6 l. These differences were not statistically significant. If both the volume of chemotherapy solution and the total dose of mitomycin C were determined from the body surface area, the pharmacokinetics of intraperitoneal mitomycin C were more consistent. Conclusions: In order to prescribe a uniform treatment for patients receiving hyperthermic intraperitoneal mitomycin C, the total dose of the drug and the total volume of chemotherapy solution should be determined from the body surface area. If the volume of chemotherapy solution is not based on patient body surface area, predictions regarding toxicity are less precise.