Anti-inflammatory effects of carprofen, carprofen enantiomers, and N(G)-nitro-L-arginine methyl ester in sheep.

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To assess anti-inflammatory effects of carprofen (CPF), CPF enantiomers, and N(G)-nitro-L-arginine methyl ester (LNAME) in sheep. 8 sheep. Sheep with SC tissue cages were used. After intracaveal injection of 1% carrageenan, sheep were given single doses of racemic (Rac; 50:50 mixture of S[+] and R[-] enantiomers)-CPF (4.0 mg/kg), R(-)CPF (2.0 mg/kg), S(+)CPF (2.0 mg/kg), LNAME (25 mg/kg), and placebo (PLB) IV in a crossover design. Rac-CPF and S(+)CPF inhibited serum thromboxane2 (TXB2) and exudate prostaglandin (PG)E2 generation significantly for 32 hours. Maximal inhibitory effect for serum TXB2 was 79+/-3% for Rac-CPF and 68+/-6% for S(+)CPF. The Rac-CPF and S(+)CPF induced 50 to 98% reversible inhibitory effect for exudate PGE2 generation during a 4- to 32-hour period. The R(-)CPF and LNAME attenuated serum TXB2 generation significantly. The R(-)CPF did not affect exudate PGE2 production, whereas L-NAME potentiated exudate, PGE2 generation by 30% during 4 to 32 hours. The S(+)CPF and LNAME increased leukotriene B4 generation and WBC recruitment in exudate although significance was achieved only at a few time points. Increase in skin temperature over inflammatory cages was effectively inhibited by Rac-CPF and S(+)CPF but not by R(-)CPF CONCLUSIONS AND CLINICAL RELEVANCE: Carprofen is a potent cyclooxygenase inhibitor in vivo in sheep, and its anti-inflammatory effects are attributable only to S(+)CPF in Rac-CPF. Nitric oxide may enhance eicosanoid production and accelerate the acute inflammatory process.