Pharmacokinetic study of intralesional cisplatin for the treatment of hepatocellular carcinoma.

BACKGROUND: In the current study the authors examined the pharmacokinetics of direct intralesional injection of cisplatin/epinephrine/bovine collagen gel in patients with hepatocellular carcinoma and cirrhosis.
METHODS: Six patients with cirrhosis and unresectable hepatocellular carcinoma received a direct intralesional injection (range, 6.7-26.7 mg) into their tumors under ultrasonographic guidance. The authors determined the total cisplatin (Pt) concentration in the plasma and urine and nonprotein-bound free Pt in plasma ultrafiltrate using flameless atomic absorption spectrometry. Data from individual patients were analyzed to calculate the pharmacokinetic parameters via a noncompartmental method for constant infusion. To demonstrate that the changes in pharmacokinetics are not related to the underlying cirrhosis, a similar methodology was applied to measure the pharmacokinetic parameters of four similar patients who were treated with cisplatin, 75 mg/m(2), as a 1-hour intravenous infusion.
RESULTS: The time to attain maximum concentration of total Pt after intralesional injection was dose-dependent and ranged from 2-13 hours. The concentration-time curve was biphasic in nature. The initial half-life of total Pt in patients who received an intralesional injection varied with the cisplatin dose. The initial half-life for cisplatin doses < 15 mg was approximately 9 hours and the initial half-life at higher cisplatin doses (> 15 mg) was approximately 25 hours. The area under the curve (AUC) was dose-dependent with values ranging from 38-150 microm/mL x hour. Pharmacokinetic parameters for free Pt (ultrafiltrate) were significantly different. The time to attain maximum concentration (t-max) and terminal half-life were shorter and the average AUC was approximately 100-fold lower than total Pt. After the intravenous infusion of cisplatin, the t-max for total and free Pt was 1.3 hours and 1.1 hours, respectively. The terminal half-life and average AUC for total Pt was 194 hours and 247 microg/mL per hour, respectively, and its corresponding parameters for free Pt after intravenous infusion were much lower, similar to the findings for the intralesional injection.
CONCLUSIONS: The prolonged t-max and initial half-life noted with the intralesional injection of cisplatin/epinephrine/collagen gel are consistent with its proclaimed ability to retain cisplatin at the tumor and delay its release in systemic circulation. The kinetics of intralesional cisplatin injection also suggest local sequestration of the drug in the injected site. Parameters of intravenous cisplatin infusion in cirrhotic patients are similar to those of patients from the historic control group. Copyright 2001 American Cancer Society.