Pharmacokinetics and dosimetry of the antiandrogen vinclozolin after oral administration in the rat

Vinclozolin (V) is a fungicide with antiandrogenic properties. To determine the pharmacokinetics and dosimetry of V, adult male rats were administered an oral dose of V (100 mg/kg) in corn oil and sacrificed over time after dosing. V and its metabolites were analyzed in serum and tissues by high performance liquid chromatography/diode array detector/mass spectrometer. V, 2-[[(3,5-dichlorophenyl)-carbamoyl]oxy]-2-methyl-3-butenoic acid (M1), and 3',5'-dichloro-2-hydroxy-2-methylbut-3-enanilide (M2), and five other metabolites were detected in serum and tissues. One metabolite was identified as 3',5'-dichloro-2,3,4-trihydroxy-2-methylbutylanilide (M5). The mean serum concentration data for V were fitted to a one-compartment model for kinetic analysis. At 2 h, V serum concentration peaked; whereas only trace levels were detected at 24 h (t(1/2 elim) = 3.6 h). V was detected in all tissues and preferentially accumulated in fat. M1 serum levels increased until 8 h, being at least 2-fold higher than those of V at this time, and then declined with a t(1/2) = 3.3 h. M5 was the main metabolite in serum and tissues. Serum M5 levels were 5-fold higher than V and 2-fold greater than M1 at all times. At 48 h, M5 remained the main metabolite (t(1/2) (elim) = 13.1 h). Liver and kidney exhibited the highest levels of M5, V, and M1. M2 and 3,5-dichloroaniline had the lowest levels of V metabolites in serum and tissues. V is well absorbed, extensively metabolized and widely distributed. M5, the most abundant V metabolite, may be used as an exposure biomarker for pharmacokinetic modeling. These results may clarify the relationship between toxicity and tissue dose of V and its metabolites.