Kinetics of cisplatin in an anuric patient undergoing hemofiltration dialysis

After in vitro tests, a tracer dose of cisplatin was administered to an anuric cancer patient. Plasma total platinum levels were monitored as a function of time, as was filterable platinum elimination by hemofiltration dialysis. Based on the derived pharmacokinetic parameters, the patient was later given 50-mg doses of cisplatin, once as a single agent, then four times in combination with doxorubicin, VM-26, and cyclophosphamide. Plasma levels could be fitted by a sum of three exponentials after the infusion was stopped. The mean corresponding half-lives are 30 minutes, 6 hours, and 5 days. Depending on the rate of infusion, plasma peaks ranged between 1.1 micrograms/ml (5.7 X 10(-6) M) and 2.27 micrograms/ml (1.16 X 10(-5) M). During the hemofiltration process immediately following the infusion, the elimination rate was first-order, with a mean half-life of 60 minutes. The mean amount eliminated during the first hemofiltration session was 8% of the dose, decreasing to about 3% on Days 2 and 3. A partial tumor response was observed after two treatment courses, evidenced by the relief of abdominal pain and bowel obstruction episodes and a 50% decrease in peritoneal metastases.