title: Pharmacokinetic behavior of doxycycline after intramuscular injection in sheep.
abstract: OBJECTIVE
  To determine the pharmacokinetics of a commercial formulation of doxycycline hyclate after IM administration of a single dose to sheep.
  
  
  METHODS
  11 healthy domestic sheep.
  
  
  METHODS
  For each sheep, doxycycline was administered as a single dose of 20 mg/kg, IM. Blood samples were obtained prior to and for 84 hours after doxycycline administration. Plasma concentrations of doxycycline were determined via high-performance liquid chromatography with UV detection. Pharmacokinetic data were analyzed with noncompartmental methods.
  
  
  RESULTS
  Mean ± SD values for pharmacokinetic parameters included maximum plasma concentration (2.792 ± 0.791 μg/mL), time to reach maximum plasma concentration (0.856 ± 0.472 hours), mean residence time (91.1 ± 40.78 hours), elimination half-life (77.88 ± 28.45 hours), and area under the curve (65.67 ± 9.877 μg•h/mL).
  
  
  CONCLUSIONS
  Results indicated that doxycycline had prolonged absorption and elimination in sheep after IM administration. A daily dose of 20 mg/kg would be sufficient to reach effective plasma concentrations against Chlamydia spp (minimum inhibitory concentration, 0.008 to 0.031 μg/mL) and Staphylococcus aureus (minimum inhibitory concentration, 0.12 μg/mL). Doxycycline administered IM could be an option for therapeutic use in sheep, although further studies are needed.
authors.affiliation: Department of Biomedical Sciences, Institute of Biomedicine, Veterinary Faculty, University of Leon, León, Spain.
authors.forename: Luis J
authors.initials: LJ
authors.lastname: Castro Robles
authors.forename: Ana M
authors.initials: AM
authors.lastname: Sahagún Prieto
authors.forename: M Jose
authors.initials: MJ
authors.lastname: Diez Liébana
authors.forename: Nélida
authors.initials: N
authors.lastname: Fernández Martínez
authors.forename: Matilde
authors.initials: M
authors.lastname: Sierra Vega
authors.forename: Juan J
authors.initials: JJ
authors.lastname: García Vieitez
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use; D001424:Bacterial Infections / Q000188:drug therapy / Q000662:veterinary; D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D004318:Doxycycline / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics* / Q000627:therapeutic use; D005260:Female; D006207:Half-Life; D007273:Injections, Intramuscular / Q000662:veterinary; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D012756:Sheep; D012757:Sheep Diseases / Q000188:drug therapy
chemical_list: D000900:Anti-Bacterial Agents; D004318:Doxycycline