RT Journal Article SR Electronic T1 Disposition of the Herbicide 2-Chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (Atrazine) and Its Major Metabolites in Mice: A Liquid Chromatography/Mass Spectrometry Analysis of Urine, Plasma, and Tissue Levels JF Drug Metabolism and Disposition JO Drug Metab Dispos FD American Society for Pharmacology and Experimental Therapeutics SP 776 OP 786 DO 10.1124/dmd.108.024927 VO 37 IS 4 A1 Matthew K. Ross A1 Toni L. Jones A1 Nikolay M. Filipov YR 2009 UL http://dmd.aspetjournals.org/content/37/4/776.abstract AB 2-Chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine, ATR) is a toxicologically important and widely used herbicide. Recent studies have shown that it can elicit neurological, immunological, developmental, and biochemical alterations in several model organisms, including in mice. Because disposition data in mice are lacking, we evaluated ATR's metabolism and tissue dosimetry after single oral exposures (5–250 mg/kg) in C57BL/6 mice using liquid chromatography/mass spectrometry (Ross and Filipov, 2006). ATR was metabolized and cleared rapidly; didealkyl ATR (DACT) was the major metabolite detected in urine, plasma, and tissues. Plasma ATR peaked at 1 h postdosing and rapidly declined, whereas DACT peaked at 2 h and slowly declined. Most ATR and metabolite residues were excreted within the first 24 h. However, substantial amounts of DACT were still present in 25- to 48-h and 49- to 72-h urine. ATR reached maximal brain levels (0.06–1.5 μM) at 4 h (5–125 mg/kg) and 1 h (250 mg/kg) after dosing, but levels quickly declined to <0.1 μM by 12 h in all the groups. In contrast, strikingly high concentrations of DACT (1.5–50 μM), which are comparable with liver DACT levels, were detectable in brain at 2 h. Brain DACT levels slowly declined, paralleling the kinetics of plasma DACT. Our findings suggest that in mice ATR is widely distributed and extensively metabolized and that DACT is a major metabolite detected in the brain at high levels and is ultimately excreted in urine. Our study provides a starting point for the establishment of models that link target tissue dose to biological effects caused by ATR and its in vivo metabolites. The American Society for Pharmacology and Experimental Therapeutics