title: Bioavailability of a commercial formulation of ivermectin after subcutaneous administration to sheep.
abstract: OBJECTIVE
  To evaluate bioavailability and other pharmacokinetic variables of a commercial formulation of ivermectin after IV administration to sheep.
  
  
  METHODS
  6 healthy adult sheep.
  
  
  METHODS
  A single dose of a commercial formulation of ivermectin (200 microg/kg) was administered IV to each sheep. After a washout period of 3 weeks, each sheep was administered ivermectin by SC injection. Plasma samples were obtained for up to 36 and up to 42 days after IV and SC administration, respectively. Ivermectin concentrations were quantified by use of high-performance liquid chromatography with fluorescence detection.
  
  
  RESULTS
  Results obtained indicated that after IV administration, ivermectin is cleared slowly from plasma, tends to distribute and accumulate in the peripheral compartment, and is slowly eliminated from the body. After SC administration, noncompartmental analysis revealed that bioavailability of ivermectin is nearly complete (98.20%), has a slow mean absorption time of 0.96 days, and reaches a maximum plasma concentration of 19.55 ng/mL at 3.13 days.
  
  
  CONCLUSIONS
  The commercial formulation of ivermectin used in this study can be administered SC to sheep on the basis of a nearly complete bioavailability. In addition, the maximum plasma concentration and interval from SC injection until maximum plasma concentration is obtained are higher than those reported by other authors who used other routes of administration.
authors.affiliation: Department of Pharmacology and Toxicology, Veterinary Faculty, University of León, Campus de Vegazana s/n 24071, León, Spain.
authors.forename: Aranzazu Gonzalez
authors.initials: AG
authors.lastname: Canga
authors.forename: Ana
authors.initials: A
authors.lastname: Sahagun
authors.forename: M Jose
authors.initials: MJ
authors.lastname: Diez
authors.forename: Nelida
authors.initials: N
authors.lastname: Fernandez
authors.forename: Matilde
authors.initials: M
authors.lastname: Sierra
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Garcia
mesh_terms: D000818:Animals; D000977:Antiparasitic Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D001682:Biological Availability; D005260:Female; D007275:Injections, Intravenous / Q000662:veterinary; D007279:Injections, Subcutaneous / Q000662:veterinary; D007559:Ivermectin / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D012756:Sheep / Q000378:metabolism*
chemical_list: D000977:Antiparasitic Agents; D007559:Ivermectin