The metabolic disposition and pharmacokinetics of TNP-470 were investigated in rhesus monkeys following intravenous administration of 5 mg/kg of [3H]-TNP-470. Rapid and extensive metabolism of parent drug to six metabolites occurred as demonstrated by the absence of unchanged drug in plasma and urine at time points as early as 6 min after administration. Substantial, yet variable, plasma levels of M-IV were detected in all three monkeys with a mean Cmax value of 3.54 microM. Five other metabolites, labeled M-I, M-II, M-III, M-V and M-VI, were also detected in biological fluids of monkeys. M-II, M-V and M-VI exhibited similar kinetic profiles with apparent plasma elimination half-life values of 0.91 +/- 0.37, 2.42 +/- 0.13 and 1.19 +/- 0.29 h respectively. In contrast, M-I, M-III and M-IV exhibited much shorter apparent plasma half-life values of 30 min or less. Urinary recovery within 36 h represented only 19.90 +/- 6.09% of the total administered dose. No radioactivity was detected beyond 36 h and during a 15-day sample collection period, suggesting that nonrenal (biliary) elimination of TNP-470 metabolites is a predominant excretion route in nonhuman primates. This study provides the first detailed in vivo analysis of TNP-470 metabolism and disposition using an animal model highly predictive of humans, consistent with the detection of the same TNP-470 metabolites in human tissues. A detailed understanding of TNP-470 metabolism and disposition is critical to fully elucidate the pharmacodynamic properties of this new anticancer drug as clinical investigations proceed.