Used in the treatment of rare kidney diseases, particularly focal segmental glomerulosclerosis (FSGS), sparsentan helps reduce proteinuria, which is excessive protein in the urine. It works by blocking both endothelin and angiotensin II receptors, two pathways involved in kidney damage and blood pressure regulation. This dual action helps preserve kidney function and slow disease progression. It is taken orally and offers a targeted approach for patients with significant protein loss who have limited treatment options.