title: Phenylbutazone and flunixin meglumine used singly or in combination in experimental lameness in horses.
abstract: BACKGROUND
  Using an adjustable heart bar shoe model of foot pain, the objective of this study was to test the hypothesis that the combined use of phenylbutazone (PBZ) and flunixin meglumine (FM) would prove more efficacious in alleviating lameness than either drug alone.
  
  
  METHODS
  One hour after induction of lameness at weekly intervals, 8 healthy adult Thoroughbred horses randomly underwent one of 4 i.v. treatments: saline (SAL) placebo (1 ml/45 kg bwt), PBZ (4.4 mg/kg bwt), FM (1.1 mg/kg bwt) or PBZ+FM (at the same dosages as given individually). Heart rate (HR) and lameness score (LS) responses were assessed in a blinded manner every 20 min for 5 h after lameness induction and then hourly for 12 h after treatment. Jugular venous blood samples were obtained at -1, 0, 0.05, 1, 2, 4, 6, 8, 10 and 12 h and subsequently analysed for drug concentrations. Repeated measures ANOVA and post hoc Tukey's test were used to identify analgesic effects at a significance level of P<0.05.
  
  
  RESULTS
  Heart rate was lower in all nonsteroidal anti-inflammatory drug (NSAID)-treated trials from 2 h to 10 h post treatment (P<0.05). Analgesic effects of FM and PBZ+FM, as evidenced by decreases in HR, lasted for 12 h post treatment (P<0.05). Lameness score decreased earlier in PBZ and PBZ+FM trials than in FM trials (P<0.05) and the analgesic effect on LS lasted for 12 h post treatment for all NSAID trials (P<0.05). Peak PBZ plasma concentration was 73.7 ± 6.0 and 77.9 ± 5.5 µg/ml. Peak FM concentration was 12.0 ± 0.8 and 13.7 ± 1.0 µg/ml.
  
  
  CONCLUSIONS
  It was concluded that the combination of PBZ+FM was not more effective than either PBZ or FM alone. These data do not support the hypothesis that the combination is more efficacious at these dosages than either drug alone in this model of acute foot pain.
authors.affiliation: Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA. jhf@illinois.edu
authors.forename: J H
authors.initials: JH
authors.lastname: Foreman
authors.forename: R
authors.initials: R
authors.lastname: Ruemmler
mesh_terms: D000818:Animals; D003002:Clonixin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use; D018592:Cross-Over Studies; D004359:Drug Therapy, Combination; D005260:Female; D005534:Foot Diseases / Q000188:drug therapy / Q000662:veterinary; D006339:Heart Rate; D006734:Horse Diseases / Q000188:drug therapy*; D006736:Horses; D007794:Lameness, Animal / Q000188:drug therapy*; D008297:Male; D010146:Pain / Q000188:drug therapy / Q000662:veterinary*; D010653:Phenylbutazone / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use*; D013997:Time Factors
chemical_list: C014558:flunixin meglumine; D010653:Phenylbutazone; D003002:Clonixin