Pharmacokinetics of free platinum species following rapid, 3-hr and 24-hr infusions of cis-diamminedichloroplatinum (II) and its therapeutic implications.

The pharmacokinetics of free platinum species derived from cis-diamminedichloroplatinum (II) (cisplatin) was studied in three patients who received the drug as a single agent for the first time at equal doses (100 mg/m2) but with different infusion times. In rapid, 3-hr and 24-hr infusions, peak levels of free platinum were 8.62, 1.96 and 0.27 microgram Pt/ml respectively; half-lives of disposition calculated 0-30 min after the end of each infusion were 17.4, 22.7 and 26.2 min respectively. Free platinum availability, measured as the area under the curves of the free platinum concentration, was the same for the three modes of administration (290, 321 and 325 micrograms Pt/min/ml-1 respectively). This observation supports the clinical impression that antitumour activity of cisplatin is not dependent on the method of administration.