600010 Disclosed is Crystalline form 6 of bosentan (4-tert-butyl-N-[6-(2-hydroxyethoxy)-5-(2-methoxyphenoxy)-2-(2-pyrimidinyl)-pyrimidin-4-yI]-benzenesulfonamide), characterized by an X-ray diffraction pattern comprising peaks at values 3.87, 7.51, 8.84, 11.14, 18.74 and 23.30 -0.2 plus or minus 0.2 degrees theta. The crystalline form of bosentan is useful for treating or preventing an endothelien receptor mediated disorder such as cardiovascular disorders. Specific cardiovascular disorders treated include hypertension, pulmonary hypertension, ischemia, vasospasm or angina pectoris.
