title: The relative plasma availabilities of ivermectin in reindeer (Rangifer tarandus tarandus) following subcutaneous and two different oral formulation applications.
abstract: BACKGROUND
  Overwintering (breeding) reindeer (Rangifer tarandus tarandus) are commonly treated with ivermectin against parasitic infestations once yearly in autumn-winter roundups. The only preparations registered to reindeer are those for subcutaneous injection. However, also oral extra-label ivermectin administration is used. Twenty-six, 8-month-old reindeer calves were randomly allocated into three groups. Group 1 (n = 9) received oral ivermectin mixture (Ivomec® vet mixt. 0.8 mg/ml, oral ovine liquid drench formulation), Group 2 (n = 9) oral ivermectin paste (Ivomec® vet 18.7 mg/g equine paste), and Group 3 (n = 8) subcutaneous injection of ivermectin (Ivomec® 10 mg/ml vet inj.), each group at a dose of 200 μg/kg body weight. Blood samples were collected at treatment and at days 1, 2, 3, 6, 9 and 16 post treatment. Plasma concentrations of ivermectin were determined by high-pressure liquid chromatography (HPLC) with fluorescence detection.
  
  
  RESULTS
  The peak plasma concentration (Cmax) was reached by 2 days after each treatment. The Cmax and Area Under Curve (AUC) differed significantly between the groups: Cmax was 30.2 ± 3.9, 14.9 ± 5.7 and 63.1 ± 13.1 ng/ml, and AUC∞ was 2881 ± 462, 1299 ± 342 and 6718 ± 1620 ng*h/ml for groups 1, 2 and 3, respectively (mean ± standard deviation).
  
  
  CONCLUSIONS
  The differences in plasma concentrations of ivermectin are concomitant with earlier observed differences in antiparasitic efficacy, which discounts the use of the equine paste in reindeer in favour of the oral ovine liquid drench formulation, or preferably, the reindeer-registered subcutaneous injection formulation.
authors.affiliation: Finnish Food Safety Authority Evira, Production Animal and Wildlife Health Research Unit (FINPAR), Elektroniikkatie 3, FI-90590, Oulu, Finland. Antti.Oksanen@evira.fi.
authors.forename: Antti
authors.initials: A
authors.lastname: Oksanen
authors.affiliation: Department of Arctic and Marine Biology, Research Group of Arctic Infection Biology, University of Tromsø, P.O. Box 6050, Langnes, NO-9037, Tromsø, Norway. Kjetil.Asbakk@uit.no.
authors.forename: Kjetil
authors.initials: K
authors.lastname: Åsbakk
authors.affiliation: Faculty of Veterinary Medicine, Department of Equine and Small Animal Medicine, Pharmacology and Toxicology Section, University of Helsinki, P.O. Box 57, FI-00014, Helsinki, Finland. Marja.Raekallio@helsinki.fi.
authors.forename: Marja
authors.initials: M
authors.lastname: Raekallio
authors.affiliation: Finnish Game and Fisheries Research Institute, Reindeer Research Station, FI-99910, Kaamanen, Finland. Mauri.Nieminen@rktl.fi.
authors.forename: Mauri
authors.initials: M
authors.lastname: Nieminen
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000871:Anthelmintics / Q000097:blood / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D005260:Female; D007279:Injections, Subcutaneous / Q000662:veterinary; D007559:Ivermectin / Q000097:blood / Q000493:pharmacokinetics*; D008297:Male; D012053:Reindeer / Q000378:metabolism*
chemical_list: D000871:Anthelmintics; D007559:Ivermectin