Sitaxsentan sodium

Sitaxsentan sodium (TBC-11251) is a selective endothelin receptor-A antagonist with IC50 and Ki value of 1.4 nM and 0.43 nM, respectively. Sitaxsentan sodium inhibits ET-1-induced stimulation of phosphoinositide turnover with a Ki of 0.69 nM and a pA2 of 8.0. Sitaxsentan blocks the action of endothelin (ET) on the endothelin-A (ETA) receptor selectively (by a factor of 6000 compared to the ETB). Sitaxsentan blocked increased plasma endothelin levels in the prevention protocol but did not affect the established elevated levels in the intervention study.