How do you approach the use of endothelin receptor antagonists in patients with scleroderma renal crisis and hypertension refractory to maximum ACE inhibition and calcium channel blockers?

There is pathologic evidence of endothelin being increased in the renal biopsies of patients with scleroderma renal crisis. There has been one small prospective open study where endothelin receptor antagonists were used in addition to ACE inhibitors in some refractory patients and compared to histor...