title: Pharmacokinetics and safety of single and multiple oral doses of meloxicam in adult horses.
abstract: BACKGROUND
  Safety of meloxicam, a potent NSAID with selective COX-2 inhibition, has not been evaluated in horses.
  
  
  OBJECTIVE
  To evaluate pharmacokinetics and safety of single and repeated oral doses of meloxicam in adult horses.
  
  
  METHODS
  Forty-nine healthy, university-owned adult lightbreed horses.
  
  
  METHODS
  Study conducted in 2 parts. Part I addressed pharmacokinetics of single oral dose meloxicam (0.6 mg/kg) in 16 horses. Part II, 33 horses were randomly assigned to 5 treatment groups to assess prolonged administration (0.6 mg/kg PO q24h for 6 weeks, n = 7) or higher doses (1.8 mg/kg, n = 7, or 3.0 mg/kg PO q24h, n = 7) of meloxicam for 2 weeks, compared with control horses (placebo, n = 7, or phenylbutazone, 4.4 mg/kg q12h on day 1, 2.2 mg/kg q12h for 4 days, then 2.2 mg/kg q24h for 9 days, n = 5).
  
  
  RESULTS
  Maximum plasma concentration following a single oral dose of meloxicam was 915.1 ± 116.9 ng/mL and elimination half-life 10.2 ± 3.0 hours. Meloxicam (0.6 mg/kg, q24h, PO for 6 weeks) yielded plasma concentrations between 100 and 1000 ng/mL and was well tolerated by healthy adult horses. Administration of 3-5 times the recommended dose of meloxicam was associated with decreased total serum protein and albumin concentrations, gastrointestinal damage, renal damage, or bone marrow dyscrasia. PBZ administration was associated with the development right dorsal colitis, gastric ulceration, and protein losing enteropathy in 2 horses.
  
  
  CONCLUSIONS
  Administration meloxicam at 0.6 mg/kg q24h was well tolerated for 6 weeks, without drug accumulation in plasma. Higher doses were associated with dose-dependent adverse effects typical of class of drugs.
authors.affiliation: School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, NSW, Australia.
authors.forename: G
authors.initials: G
authors.lastname: Noble
authors.forename: S
authors.initials: S
authors.lastname: Edwards
authors.forename: J
authors.initials: J
authors.lastname: Lievaart
authors.forename: J
authors.initials: J
authors.lastname: Pippia
authors.forename: R
authors.initials: R
authors.lastname: Boston
authors.forename: S L
authors.initials: SL
authors.lastname: Raidal
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000493:pharmacokinetics*; D019540:Area Under Curve; D016861:Cyclooxygenase Inhibitors / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D005260:Female; D005773:Gastroscopy / Q000662:veterinary; D006207:Half-Life; D006736:Horses / Q000097:blood / Q000378:metabolism*; D008297:Male; D000077239:Meloxicam; D013843:Thiazines / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000493:pharmacokinetics*; D013844:Thiazoles / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000493:pharmacokinetics*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D016861:Cyclooxygenase Inhibitors; D013843:Thiazines; D013844:Thiazoles; D000077239:Meloxicam