Utilization of a murine model to optimize volume and dwell time of intraperitoneal cisplatin

The pharmacokinetics of intraperitoneal (ip) cisplatin were investigated in a murine model. Groups of six animals were studied at initial cisplatin concentrations (Ci) of 50, 100, 200, and 400 micrograms/ml, and at injection volumes (V) of 0.5, 1, 2, and 4 ml. For each Ci and V, four dwell times (Dt) between 1.5 and 120 min were studied. At 180 min mice were killed and five tissues (heart, kidney, liver, bowel, and peritoneum) were obtained for platinum measurement. Platinum recovered from the peritoneal cavity at the end of the dwell time and platinum tissue levels were determined by a radioactive tracer assay using Pt 195m-labeled cisplatin. A total of 384 mice were studied. The permeability times the effective surface area product (pS) was found to be independent of Ci, V, and Dt. Platinum tissue levels were proportional to absorbed dose. As the ratio of platinum tissue level to absorbed dose is constant, it is not possible to change Ci, V, nor Dt to minimize toxicity from a given absorbed dose. This study suggests that the therapeutic index of an individual intraperitoneal cisplatin treatment will not be changed by modifying Ci, V, nor Dt.