The analgesic NSAID lornoxicam inhibits cyclooxygenase (COX)-1/-2, inducible nitric oxide synthase (iNOS), and the formation of interleukin (IL)-6 invitro

Objective: To investigate anti-inflammatory effects of lornoxicam in vitro on COX-1/COX-2, on NO formation from iNOS and on the formation of the pro-i nflammatory cytokines TNF-alpha, IL-1 beta, IL-6, and IL-8. Materials and Methods: COX-1 inhibition in intact cells was assessed employ ing two systems: measurement of aggregation in human washed platelets and a ssessment of TXB2 formation in HEL cells. COX-2 inhibition was assessed by measuring 6-keto-PGF(1 alpha) in supernatants of intact cells of LPS-stimul ated J774.2 cells (murine) and of Mono Mac 6 cells (human). In whole blood inhibition of COX-1 was performed by measuring TXB2 formation after clottin g, and COX-2 inhibition was examined in LPS-stimulated whole blood cultures . The reduction of NO levels as a measure of the inhibition of cellular NO formation was assayed in supernatants of LPS-stimulated RAW 264.7 cells usi ng the Griess reaction. Compound influence on the formation of TNF-alpha, I L-1 beta, IL-6, and IL-8 was examined using LPS-stimulated monocytic cells (THP-1) and measurement of cytokine concentrations by specific ELISAs. Results: In intact human cells, lornoxicam showed a balanced inhibition of COX-1/-2 exhibiting the lowest IC50 (0.005 mu M/0.008 mu M) of the large pa nel of NSAIDs tested. Similar results were obtained in the whole blood for COX-1/-2. NO formation was dose-dependently inhibited by lornoxicam (IC50 o f 65 mu M) whereas piroxicam, diclofenac, ibuprofen, ketorolac and naproxen inhibited the NO formation markedly less. Indomethacin was approximately e quipotent with lornoxicam. In stimulated monocytic cells (THP-1), lornoxica m showed a marked inhibition of IL-6 formation (IC50 54 mu M) while the for mation of TNF-alpha, IL-1 beta and IL-8 was only moderately affected. Conclusions: Of the panel of NSAIDs tested, lornoxicam was found to be the most potent balanced inhibitor of human COX-1/-2. The equipotent COX-isoenz yme inhibition by lornoxicam is complemented by a marked inhibition of IL-6 production and of iNOS-derived NO formation. The in vitro activities descr ibed support the marked anti-inflammatory and analgesic activities of lorno xicam found in animal models as well as in clinical studies.