Stereoselective degradation kinetics of tebuconazole in rabbits

Tebuconazole[( RS )‐1‐ p ‐chlorophenyl‐4,4‐dimethyl‐3‐(1 H ‐1,2,4‐triazol‐1‐ylmethyl)pentan‐3‐ol] is a potent triazole fungicide and consists of a pair of enantiomers. The enantioselective degradation kinetics of tebuconazole was investigated in rabbits by intravenous (iv) injection. The concentrations of (−)‐( R )‐tebuconazole and (+)‐( S )‐tebuconazole in plasma and tissues were determined by HPLC with a cellulose tris(3,5‐dimethylphenylcarbamate)‐based chiral stationary phase. Enantioselective analysis methods for this fungicide in plasma and tissues were developed and validated. Good linearities were obtained over the concentration range of 0.25–25 mg/l for both enantiomers. The degradation followed pseudo‐first‐order kinetics and the degradation of the (+)‐( S )‐tebuconazole was much faster than that of the (−)‐( R )‐tebuconazole in plasma after administration of racemic tebuconazole. This study also indicated that environmental assessment of enantiomeric degradation may be needed to fully evaluate risks of tebuconazole use. Chirality, 2007. © 2006 Wiley‐Liss, Inc.