Clinical pharmacokinetics of intraarterial cisplatin in humans

The pharmacokinetics of intraarterially administered cisplatin (DDP) were studied in three patients with large hepatic tumors, and one patient with a fibrous histiocytoma in the thigh, using an assay sensitive to only those forms of non-protein bound DDP capable of reacting with the nucleophilic ligand diethyldithiocarbamate. Each patient received continuous intravenous and intraarterial infusions at various dose rates, with and without concurrent infusion of the neutralizing agent sodium thiosulfate. Steady-state DDP concentrations were achieved within two hours, and the mean (+/- SEM) plasma clearance at infusion rates of 5-15 mg/m2 per hour was 345 +/- 45 mL/m2 per minute. Apparent plasma clearance did not vary significantly with route of infusion. Based on the plasma clearance, predicted values for the relative advantage of an intraarterial infusion (Rt) were less than two for hepatic infusion; observed values averaged 1.9 +/- 0.5 (+/- SEM). The infusion of thiosulfate did not significantly increase plasma clearance. The mean (+/- SEM) extraction ratio for hepatic infusions was 0.24 +/- 0.09, and for infusion of the peripheral soft tissue sarcoma it was 0.27 +/- 0.03. These data indicate that from the point of view of both the tumor and the systemic circulation there is only a limited pharmacologic advantage for intraarterial infusion of DDP into organs with plasma flows of greater than 350 mL/m2 per minute.