title: In vivo absorption, distribution, excretion, and metabolism of a new herbicide, methiozolin, in rats following oral administration.
abstract: Methiozolin [5-(2,6-difluorobenzyl)oxymethyl-5-methyl-3-(3-methylthiophen-2-yl)-1,2-isoxazoline] is a new turf herbicide that controls annual bluegrass in various cool- and warm-season turfgrasses. The present study is the first report elucidating absorption, tissue distribution, excretion, and metabolism of methiozolin in rats. The pharmacokinetic parameters in the blood were observed as follows: t(max) = 6 h, C(max) = 168.7 μg equiv/mL, t(½) = 49.4 h, AUC₁₂₀ = 9921.5 μg equiv·h/mL, and clearance = 39.2 mL/h/kg. Those parameters and the depletion curve for ¹⁴C in the plasma were very similar to those in the blood. Total excretion through urine and feces was 24.3 and 68.9%, respectively, during 120 h after administration; however, there was no excretion through expired air. The radioactivity excreted through bile was 40.1% of that administered. Excreted radioactivity peaked between 24 and 48 h, showing 51.0% of total excretion within 48 h. The orally administered ¹⁴C distributed across various tissues within 12 h after administration, showing 14.0% of the dosed, and was eliminated from all tissues without accumulation. Numerous minor metabolites (<4% of the dosed) in urine and fecal extract were detected within 72 h, and two of those were identified. The identified metabolites were Met-1 (glucuronic acid conjugate), 6-[5-(5-((2,6-difluorobenzyloxy)methyl)-4,5-dihydro-5-methylisoxazol-3-yl)-4-methylthiophen-2-yloxy]-tetrahydro-3,4,5-trihydroxy-2H-pyran-2-carboxylic acid, and Met-2, [2-(5-((2,6-difluorobenzyloxy)methyl)-4,5-dihydro-5-methylisoxazol-3-yl)thiophen-3-yl]methanol. Conclusively, methiozolin was shown to be readily absorbed in the gastrointestinal tract, distributed throughout the tissues within 12 h, metabolized extensively, and eliminated through urine and feces mostly within 48 h, without tissue accumulation.
authors.affiliation: Moghu Research Center Ltd., BVC 311, KRIBB , Yuseong, Daejeon 305-333, Korea.
authors.forename: Ki-Hwan
authors.initials: KH
authors.lastname: Hwang
authors.forename: Jong-Soo
authors.initials: JS
authors.lastname: Lim
authors.forename: Sung-Hun
authors.initials: SH
authors.lastname: Kim
authors.forename: Man-Seok
authors.initials: MS
authors.lastname: Jeon
authors.forename: Dong-Guk
authors.initials: DG
authors.lastname: Lee
authors.forename: Kun-Hoe
authors.initials: KH
authors.lastname: Chung
authors.forename: Suk-Jin
authors.initials: SJ
authors.lastname: Koo
authors.forename: Jeong-Han
authors.initials: JH
authors.lastname: Kim
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001711:Biotransformation; D006207:Half-Life; D006540:Herbicides / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism / Q000493:pharmacokinetics*; D007408:Intestinal Absorption; D007555:Isoxazoles / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism / Q000493:pharmacokinetics*; D008297:Male; D008657:Metabolic Clearance Rate; D051381:Rats; D017207:Rats, Sprague-Dawley; D013876:Thiophenes / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism / Q000493:pharmacokinetics*; D014018:Tissue Distribution
chemical_list: D006540:Herbicides; D007555:Isoxazoles; D013876:Thiophenes; C585332:methiozolin