The lipid mediator thromboxane A2 (TXA2) plays a key role in platelet aggregation and vascular and bronchial smooth muscle constriction. The actions of TXA2 are mediated by its specific G protein coupled-receptor, referred to as the TXA2 receptor or TP. S18886 is an orally active, long-acting antagonist of the TP receptor with an IC50 value of 16.4 nM. It inhibits TP receptor-mediated vascular contractions, platelet aggregation, and adhesion and infiltration of monocytes/macrophages in various pre-clinical and clinical models of thrombosis or atherosclerosis. S18886 is the active isomer of the potent TP receptor antagonist, S18204. Antagonists of TP receptors have advantages over aspirin as they not only block the effect of TXA2 on platelets, but also inhibit other ligands such as prostaglandin endoperoxides and isoprostanes.
in a previous animal study, it was found that s18886 treatment could reduce the portal pressure in both animal models without producing significant changes in portal blood flow, indicating a reduction in hepatic vascular resistance. s18886 could not significantly change arterial pressure in ccl4 -cirrhotic rats but could significantly decrease it in bdl-cirrhotic rats [2].
[1] cimetière b, dubuffet t, landras c, descombes jj, simonet s, verbeuren tj, lavielle g. new tetrahydronaphthalene derivatives as combined thromboxane receptor antagonists and thromboxane synthase inhibitors. bioorg med chem lett. 1998 jun 2;8(11):1381-6.
[2] rosado e, rodríguez-vilarrupla a, gracia-sancho j, tripathi d, garcía-calderó h, bosch j, garcía-pagán jc. terutroban, a tp-receptor antagonist, reduces portal pressure in cirrhotic rats. hepatology. 2013 oct;58(4):1424-35.
[3] bousser mg, amarenco p, chamorro a, fisher m, ford i, fox km, hennerici mg, mattle hp, rothwell pm, de cordoüe a, fratacci md; perform study investigators. terutroban versus aspirin in patients with cerebral ischaemic events (perform): a randomised, double-blind, parallel-group trial. lancet. 2011 jun 11;377(9782):2013-22.