Pharmacokinetics of ivermectin in sheep following intravenous, intra-abomasal or intraruminal administration.
The pharmacokinetics of ivermectin in plasma following intravenous, intra-abomasal, and intraruminal administration to sheep was determined. When given intravenously, ivermectin was very slowly eliminated with a terminal half-life of 178 h and a volume of distribution at steady state of 5.3 l/kg indicating sequestration in a temporary depot. Intra-abomasal administration resulted in rapid absorption, a peak plasma concentration of 60.6 ng/ml at 4.4 h, and 100% bioavailability. However, intraruminal administration produced a much lower peak concentration (17.6 ng/ml at 23.5 h) and bioavailability (25.1%). A subsequent in vitro study indicated that ivermectin may be rapidly metabolized in the rumen.
D000018:Abomasum; D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage / Q000378:metabolism*; D005260:Female; D005369:Filaricides / Q000008:administration & dosage / Q000378:metabolism*; D007275:Injections, Intravenous; D007559:Ivermectin; D007700:Kinetics; D007783:Lactones / Q000008:administration & dosage / Q000378:metabolism*; D012417:Rumen; D012756:Sheep / Q000378:metabolism*
D000871:Anthelmintics; D005369:Filaricides; D007783:Lactones; D007559:Ivermectin