title: Cyclooxygenase selectivity of nonsteroidal anti-inflammatory drugs in canine blood.
abstract: OBJECTIVE
  To evaluate cyclooxygenase (COX) selectivity of several nonsteroidal anti-inflammatory drugs (NSAID) in canine blood in vitro.
  
  
  METHODS
  11 healthy adult male hound crosses.
  
  
  METHODS
  9 NSAID were studied at 5 concentrations. Thromboxane B2 (TxB2) was assayed as a measure of COX-1 activity in clotted blood. Prostaglandin E2 (PGE2) was assayed as a measure of COX-2 activity in heparinized, lipopolysaccharide (LPS)-stimulated blood. All assays were competitive ELISA tests. Cyclooxygenase selectivity was expressed as a ratio of the concentration of an NSAID that inhibited 50% of the activity (IC50) of COX-1 to the IC50 of COX-2. A separate ratio of the concentration that inhibited 80% of COX activity (IC80) was also determined. A ratio of < 1.0 indicated selectivity for COX-1, whereas a ratio of > 1.0 indicated COX-2 selectivity.
  
  
  RESULTS
  Ketoprofen, aspirin, and etodolac were COX-1 selective. Piroxicam, meloxicam, and carprofen had COX-2 selectivity. The IC50 and IC80 values were similar for most NSAID.
  
  
  CONCLUSIONS
  This methodology provides repeatable data from individual dogs and is comparable to results of previous in vitro and ex vivo models. Findings are also consistent with those of canine studies performed in vivo, suggesting that this is a viable in vitro assessment of the COX selectivity of NSAID in dogs.
authors.affiliation: Department of Small Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
authors.forename: Heather K
authors.initials: HK
authors.lastname: Streppa
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Jones
authors.forename: Steven C
authors.initials: SC
authors.lastname: Budsberg
mesh_terms: D000818:Animals; D018592:Cross-Over Studies; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000097:blood / Q000494:pharmacology*; D015232:Dinoprostone / Q000096:biosynthesis; D004285:Dogs / Q000097:blood*; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D008297:Male; D011451:Prostaglandin-Endoperoxide Synthases / Q000097:blood / Q000187:drug effects*; D013929:Thromboxane B2 / Q000096:biosynthesis
chemical_list: D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D013929:Thromboxane B2; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone