Optimization of isoxazoline amide benzoxaboroles for identification of a development candidate as an oral long acting animal ectoparasiticide

摘要

Novel isoxazoline amide benzoxaboroles were designed and synthesized to optimize the ectoparasiticide activity of this chemistry series against ticks and fleas. The study identified an orally bioavailable molecule, (S)-N-((1-hydroxy-3,3-dimethyl-1,3-dihydrobenzo[c][1,2]oxaborol-6-yl) methyl)-2-methyl-4-(5-(3,4,5-trichlorophenyl)-5-(trifluoromethyl)-4,5-dihydroisoxazol-3-yl)benzamide (23), with a favorable pharmacodynamics profile in dogs (C-max = 7.42 ng/mL; T-max = 26.0 h; terminal half-life t(1/2) = 127 h). Compound 23, a development candidate, demonstrated 100% therapeutic effectiveness within 24 h of treatment, with residual efficacy of 97% against American dog ticks (Dermacentor variabilis) on day 30 and 98% against cat fleas (Ctenocephalides felis) on day 32 after a single oral dose at 25 mg/kg in dogs. (C) 2016 Elsevier Ltd. All rights reserved.