C5 and paroxysmal nocturnal hemoglobinuria: A better strategy would be to specifically inhibit the C5a receptor (C5aR) or C5a, which in vitro prevented the harmful effects of C5a without inhibiting the MAC complex.82,87,88 Several drugs targeting complement have been approved for patients, such as the C5 inhibitors eculizumab and raviluzumab for the treatment of paroxysmal nocturnal haemoglobinuria, and the C5aR inhibitor avacopan used in anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis.