ABSTRACT
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 (Cmax=7.42ng/mL; Tmax=26.0h; terminal half-life t1/2=127h). Compound 23, a development candidate, demonstrated 100% therapeutic effectiveness within 24h 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 25mg/kg in dogs.
Subject(s)
Amides/pharmacology , Antiparasitic Agents/pharmacology , Boron Compounds/pharmacology , Ctenocephalides/drug effects , Dermacentor/drug effects , Ectoparasitic Infestations/drug therapy , Isoxazoles/pharmacology , Administration, Oral , Amides/administration & dosage , Amides/chemistry , Animals , Antiparasitic Agents/administration & dosage , Antiparasitic Agents/chemistry , Boron Compounds/administration & dosage , Boron Compounds/chemistry , Cats , Dogs , Dose-Response Relationship, Drug , Ectoparasitic Infestations/parasitology , Isoxazoles/administration & dosage , Isoxazoles/chemistry , Molecular Structure , Parasitic Sensitivity Tests , Structure-Activity RelationshipABSTRACT
A novel series of isoxazoline benzoxaborole small molecules was designed and synthesized for a structure-activity relationship (SAR) investigation to assess the ectoparasiticide activity against ticks and fleas. The study identified an orally bioavailable molecule, (S)-3,3-dimethyl-5-(5-(3,4,5-trichlorophenyl)-5-(trifluoromethyl)-4,5-dihydroisoxazol-3-yl)benzo[c][1,2]oxaborol-1(3H)-ol (38, AN8030), which was long lasting in dogs (t1/2=22 days). Compound 38 demonstrated 97.6% therapeutic effectiveness within 24 h of treatment, with residual efficacy of 95.3% against American dog ticks (Dermacentor variabilis) on day 30% and 100% against cat fleas (Ctenocephalides felis) on day 32 after a single oral dose at 50 mg/kg in dogs.