SOLIRIS 300 mg SOLIRIS contains Eculizumab, a recombinant humanized IgG2/4κ monoclonal antibody that selectively targets and binds with high affinity to the complement protein C5, inhibiting its cleavage into C5a and C5b. By blocking terminal complement activation, it prevents the assembly of the membrane attack complex (MAC/C5b-9), suppressing complement-mediated intravascular hemolysis and thrombotic microangiopathy without interfering with early complement activation components essential for opsonization and immune complex clearance. It is indicated for the treatment of Paroxysmal Nocturnal Hemoglobinuria (PNH), Atypical Hemolytic Uremic Syndrome (aHUS), refractory generalized Myasthenia Gravis (gMG), and Neuromyelitis Optica Spectrum Disorder (NMOSD).