Flavone acetic acid distribution in human malignant tumors

The pharmacokinetics of flavone acetic acid (FAA) after a dose of 4.8 mg/m2 given i.v. over 1 h was investigated in 13 patients with different solid tumors. The mean volume of distribution and clearance were 52 +/- 4 l/m2 and 2.6 +/- 0.2 l/h x m2, respectively. A tumor or metastasis biopsy was obtained from six patients 2 h after the end of infusion. Tumor FAA levels ranged from 39.6 to 148.8 micrograms/g and were similar to those obtained after a therapeutic i.v. dose of 200 mg/kg FAA in animals bearing Pan/03 tumor, which is very sensitive to the drug. Although FAA tumor concentration could be detected only during one interval and we therefore cannot draw a definitive conclusion, differences in the agent's antitumor activity in mice and patients (i.e. very active in the former and inactive in the latter) are apparently not due to discrepancies in drug distribution and pharmacokinetics.