Bioavailability and pharmacokinetic characteristics of dexniguldipine-HCl, a new anticancer drug

Dexniguldipine-HCl is a new dihydropyridine derivative with antineoplastic activity and potency for overcoming multidrug resistance. In this pharmacokinetic study the bioavailability of 3 doses of an oral formulation of dexniguldipine was to be determined. Fourteen patients with malignant disease not eligible for higher priority treatment and sufficient general condition were included. In 12 patients all pharmacokinetic investigations were available for evaluation. A single 4-h infusion of 2 mg per kg body weight of dexniguldipine was given as reference. Thereafter 3 increasing oral dosages (750, 1,500, 2,250 mg/d) were given on a 3-time daily basis for 3 consecutive weeks. On day 7 (under steady state conditions) of each period, a pharmacokinetic profile was done. Absolute bioavailability at the 3-dose levels was 3, 4, and 5%, respectively, thus slightly increasing with dose, but generally low. After intravenous administration terminal half life was 22.4 h, clearance 36.9 l/h and volume of distribution 1,193 1. Toxicity was tolerable with main adverse events being loss of appetite, nausea, and vomiting. Cardiovascular effects and a decrease in serum calcium were reported in several patients. Patients were allowed to continue treatment if a benefit was expected, and 2 patients showed tumor regression during treatment. One patient with renal cell carcinoma achieved a partial remission. Bioavailability of this oral formulation seems too low for routine clinical use, despite the fact that clinical effects have been observed.