Danicopan is primarily used in the treatment of paroxysmal nocturnal hemoglobinuria (PNH), a rare and life-threatening blood disorder. It functions as a complement factor D inhibitor, targeting the alternative complement pathway to reduce the destruction of red blood cells, a hallmark of PNH. By inhibiting factor D, Danicopan helps control hemolysis, thereby improving symptoms such as fatigue, anemia, and the risk of thrombosis. It is often used as an add-on therapy for patients who are already being treated with C5 inhibitors like eculizumab or ravulizumab but continue to experience significant extravascular hemolysis. This targeted approach enhances the overall management of PNH, offering a more comprehensive treatment strategy for patients with this complex condition.