Pharmacotherapeutic group: Non-steroidal anti-inflammatory drug. ATC Vet Code: QM01AE91.

Carprofen is a member of the 2-arylpropionic acid group of non-steroidal anti-inflammatory drugs (NSAIDs), and possesses anti-inflammatory, analgesic and antipyretic activity. Carprofen is a chiral drug with the S(+) enantiomer being more active than the R(-) enantiomer. Carprofen, like most other NSAIDs is an inhibitor of the enzyme cyclo-oxygenase of the arachidonic acid cascade. However, the inhibition of prostaglandin synthesis by carprofen is slight in relation to its anti-inflammatory and analgesic potency. The precise mode of action of carprofen is not clear.

After oral administration, carprofen is well absorbed in the dog. Following the administration of Rimifin tablets in dogs, a mean Cmax (maximum concentration in serum) of 15.8 µg/ml and 12.2 µg/ml was achieved at approximately 2 hours and 1.7 hours for Carprofen R(-) and Carprofen S(+), respectively. For both enantiomers, the mean half-life was approximately 6 hours. The analgesic effect from each dose persists for at least 12 hours.

Carprofen has a small volume of distribution and a low systemic clearance. It is highly bound to plasma protein. Carprofen is metabolised in the liver by conjugation and oxidation. The excretion of the glycuronide conjugate is mainly faecal after biliary excretion.