Endothelin receptor antagonists(bosentan) –Endothelin is a potent vasoconstrictor of vascular smooth muscle cells.Among its other actions, bosentan exerts a consistent effect on vasculature. The Randomized Placebo-controlled Investigation of Digital ulcers in Scleroderma (RAPID-1 AND 2) trials have shown that the number of new digital ulcers in patients with secondary Raynaud’s phenomenon decreased significantly when treated with bosentan. The European League Against Rheumatism recommends its use when symptoms are refractory to treatment with calcium channel blockers and prosteglandins.