Plasma and synovial concentrations of carprofen in dogs with chronic osteoarthritis

The objective of this study was to measure the synovial and plasma concentr ation of carprofen in normal and osteoarthritic stifle joints through out a 12-hour period. Eight healthy male mixed breed hound dogs with chronic rig ht stifle osteoarthritis (OA) secondary to right cruciate ligament transect ion, were used. Each dog was treated with carprofen (2mg/kg every 12 hours) for 14 days at four different time periods. Prior to treatment, each dog h ad baseline data collected that included two force plate evaluations (seven days apart), synovial fluid, and plasma collections. Plasma samples were c ollected at three hours post drug administration on days two, four, six, ri ght, 10, and 12. On days #7 and 14 plasma, serum, bilateral stifle synovial fluid and ground reaction forces (GRFs) were collected at three, six, nine , or 12 hours post-medication, depending upon the test protocol. Vertical a nd cranio-caudal ground reaction forces were recorded at each time period. Plasma concentrations measured at three hours remained constant over each t esting protocol. There were not any differences between the plasma carprofe n concentrations at three, nine, or 12 hours between days #7 or 14. A signi ficant difference was not found in the carprofen synovial concentrations be tween left and right stifles at any time. Significant increases in vertical impulse data were found at six hours post-treatment, for all of the collec tion periods on days three, seven and 14. During the study, there was not a ny indication that carprofen had a 'preference' for the OA stifle as oppose d to the normal stifle. Carprofen administration increased the total force transmitted through the abnormal limb.