title: Comparative pharmacokinetics of doramectin and ivermectin in cattle.
abstract: Plasma pharmacokinetics were compared for 40 cattle dosed by subcutaneous injection with doramectin or ivermectin (200 micrograms kg-1), commercial formulations of doramectin or ivermectin, 20 cattle per product). Doramectin exhibited a similar peak plasma concentration to ivermectin (about 32 ng ml-1), but the time to Cmax was longer for doramectin (5.3 +/- 0.35 days) than for ivermectin (4.0 +/- 0.28 days). The area under the curve from time 0 to infinity post-injection was significantly higher (p < 0.001) for doramectin (511 +/- 16 ng day ml-1) than for ivermectin (361 +/- 17 ng day ml-1). This was explained by a lower clearance, a lower volume of distribution and, probably, a higher bioavailability of doramectin over ivermectin. It is concluded that the pharmacokinetic differences between doramectin and ivermectin may explain the longer duration of preventive efficacy of doramectin.
authors.affiliation: Ecole Nationale Vétérinaire de Toulouse, Unité associée INRA de Physiopathologie et Toxicologie Expérimentales, Toulouse, France.
authors.forename: P L
authors.initials: PL
authors.lastname: Toutain
authors.forename: D W
authors.initials: DW
authors.lastname: Upson
authors.forename: T N
authors.initials: TN
authors.lastname: Terhune
authors.forename: M E
authors.initials: ME
authors.lastname: McKenzie
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D002417:Cattle; D005260:Female; D007279:Injections, Subcutaneous; D007559:Ivermectin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics*; D008297:Male; D008657:Metabolic Clearance Rate; D009919:Orchiectomy
chemical_list: D000871:Anthelmintics; D007559:Ivermectin; C084101:doramectin