Ridogrel, a dual thromboxane synthase inhibitor and receptor antagonist: anti-inflammatory profile in inflammatory bowel disease.

Thromboxanes, prostaglandins, reactive oxygen metabolites and pro-inflammatory cytokines are produced in excess in inflammatory bowel disease. Preliminary reports suggest that ridogrel, a thromboxane synthesis inhibitor and receptor blocker, may have therapeutic benefits in ulcerative colitis. To investigate the anti-inflammatory profile of ridogrel. The effects of ridogrel on the production of eicosanoids, reactive oxygen metabolites and cytokines by cultured inflamed colorectal mucosal biopsies were made using ELISA and chemiluminescence, reactive oxygen metabolite generation in a cell-free system, and platelet activation using flow cytometry. The effects of oral ridogrel on mucosal release of eicosanoids in two patients with active ulcerative colitis were assessed using rectal dialysis. Ridogrel significantly reduced the release of thromboxane B2, but not prostaglandin E2 or tumour necrosis factor-alpha, from biopsies (P < 0.01 for 10 microM ridogrel). Ridogrel showed no direct antioxidant activity but significantly reduced reactive oxygen metabolite production from cultured biopsies (P < 0.01 for 10 microM ridogrel). Platelet activation in vitro was inhibited by ridogrel (P </= 0.05 for >/= 10 microM ridogrel). Mean rectal mucosal thromboxane B2 release was reduced to 86% of pre-treatment levels in two patients treated with oral ridogrel. Its inhibition of mucosal production of thromboxane B2, reactive oxygen metabolites, and of platelet activation, suggests that ridogrel could have a therapeutic role in inflammatory bowel disease.