title: Plasma concentrations, analgesic and physiological assessments in horses with chronic laminitis treated with two doses of oral tramadol.
abstract: BACKGROUND
  Laminitis is a painful disease for which adequate pain management remains a challenging and largely unmet medical need.
  
  
  OBJECTIVE
  To investigate plasma concentrations, analgesic and physiological effects of 2 doses of tramadol in horses with chronic laminitis.
  
  
  METHODS
  Nonrandomised trial.
  
  
  METHODS
  Four horses with naturally occurring chronic laminitis received 5 mg/kg bwt and then 10 mg/kg bwt tramadol orally every 12 h for one week with a one-week washout between. Noninvasive arterial blood pressure, heart and respiratory rates, intestinal sounds and forelimb off-loading frequency were evaluated before and during treatments. Plasma tramadol and metabolite (M1 and M2) concentrations were measured on predetermined days and times after the morning dosing.
  
  
  RESULTS
  Forelimb off-loading frequency decreased significantly with 10 mg/kg bwt (40%, P = 0.02) but not with 5 mg/kg bwt (9%, P = 0.4). Physiological variables did not change significantly with either treatment. For 5 and 10 mg/kg bwt treatments, respectively, individual maximum plasma concentrations (μg/l) ranged from 329 to 728 and 628 to 1330 (tramadol), 12-24 and 32-80 (M1), and 90-157 and 239-362 (M2). Respective median area under the concentration vs. time curves (h μg/l) were 727 and 1426, 33 and 88, 303 and 1003.
  
  
  CONCLUSIONS
  Twice daily oral tramadol at 10 mg/kg bwt may produce analgesic plasma levels in horses with chronic laminitis.
authors.affiliation: Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, USA.
authors.forename: A
authors.initials: A
authors.lastname: Guedes
authors.affiliation: K. L. Maddy Equine Analytical Chemistry Laboratory, School of Veterinary Medicine, University of California, Davis, USA.|Department of Veterinary Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, USA.
authors.forename: H
authors.initials: H
authors.lastname: Knych
authors.affiliation: Hoof Diagnostic and Rehabilitation Clinic, Bryan, Texas, USA.
authors.forename: D
authors.initials: D
authors.lastname: Hood
mesh_terms: D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use; D000818:Animals; D019540:Area Under Curve; D002908:Chronic Disease; D004305:Dose-Response Relationship, Drug; D005260:Female; D005534:Foot Diseases / Q000188:drug therapy / Q000662:veterinary*; D017619:Hemibody Irradiation; D006724:Hoof and Claw / Q000473:pathology*; D006734:Horse Diseases / Q000097:blood / Q000188:drug therapy*; D006736:Horses; D007249:Inflammation / Q000188:drug therapy / Q000662:veterinary*; D008297:Male; D014147:Tramadol / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use*
chemical_list: D000701:Analgesics, Opioid; D014147:Tramadol
keywords: analgesia; force plate; horse; inflammatory pain; neuropathic pain; opioids