To evaluate in vivo activity of carprofen, deracoxib, and etodolac on prostanoid production in several target tissues in dogs with chronic osteoarthritis.
8 dogs with chronic unilateral osteoarthritis of the stifle joint.
Each dog received carprofen, deracoxib, or etodolac for 10 days with a 30- to 60-day washout period between treatments. On days 0, 3, and 10, prostaglandin (PG) E2 concentrations were measured in lipopolysaccharide-stimulated blood, synovial fluid, and gastric mucosal biopsy specimens; PGE1 concentrations were measured in gastric mucosal biopsy specimens; and thromboxane B2 (TXB2) was evaluated in blood.
Carprofen and deracoxib significantly suppressed PGE2 concentrations in blood at days 3 and 10, compared with baseline, whereas etodolac did not. None of the drugs significantly suppressed TXB2 concentrations in blood or gastric PGE1 synthesis at any time point. All 3 drugs significantly decreased gastric synthesis of PGE2 at day 3 but not day 10 of each treatment period. All 3 drugs decreased synovial fluid PGE2 concentrations in the affected and unaffected stifle joints at days 3 and 10.
Results indicate that carprofen and deracoxib act in vivo on target tissues as COX-1-sparing drugs by sparing gastric PGE1 and PGE2 synthesis and production of TXB2 by platelets. Etodolac also appears to be COX-1 sparing but may have variable effects on COX-2 depending on the tissue. In gastric mucosa and synovial fluid, there were no significant differences in PG production between compounds at recommended concentrations.