Clinical efficacy and pharmacokinetics of carprofen in the treatment of dogs with osteoarthritis

28-day study of the effect of carprofen on six dogs

source: V.J. Lipscomb et al
Veterinary Record vol 150 no 22, June 1 2002
starts p684, 6 pages long

Six dogs of medium to large breeds were given 2mg/kg racemic carprofen a day over 28 days and this improved their lameness on average, both in terms of a visual analogue scale, and when peak vertical forces were measured for the dogs' worst affected limbs. The two older dogs, which had hip and elbow arthritis, showed obvious improvements, while two immature dogs showing hip dysplasia showed moderate improvements, and two dogs suffering elbow arthritis did not show any improvement.

Carprofen acts as an analgesic, and this appears to be the reason for the improvements shown, since its long-term effect on cartilage metabolism is not known, and chondroptective (disease-modifying) action has yet to be proven. Carprofen has a low incidence of side-effects, and none were seen in this study, but it should not be given with corticosteroids, which have been associated with gastrointestinal bleeding. Pharmacokinetic differences occurred within dogs as well as between dogs, with different absorption patterns shown on different days. Carprofen is a non-steroidal anti-inflammatory drug (NSAID) and a COX inhibitor, though this effect is absent or slight in dogs at recommended doses. Racemic carprofen is a mix of two different drugs. The mechanism by which it works is unclear. Tt has been suggested both that carprofen is a COX2 inhibitor, and that it works through non-COX mechanisms. Dogs do not appear to accumulate carprofen, or develop tolerance for the drug.

This study has found the disposition and absorption of carprofen enantiomers apparently non-enantioselective, with individual dogs showing some small variations. This means that there could be breed differences in terms of carprofen enantiomer pharmacokinetics.