The present invention concerns the compound aprocitentan, {5-(4-bromo-phenyl)-6-[2-(5-bromo-pyrimidin-2-yloxy)-ethoxy]-pyrimidin-4-yl}-sulfamide, and its use as endothelin receptor antagonist, in combination with other active ingredients or therapeutic agents including an angiotenin receptor blocker, and/or a calcium channel blocker, and preferably a diuretic which is a thiazide-like diuretic, in the prophylaxis or treatment of certain endothelin related diseases. The invention further relates to pharmaceutical compositions comprising aprocitentan in combination with said other active ingredients or therapeutic agents. The invention further relates to such pharmaceutical compositions comprising novel crystalline forms of aprocitentan.