C5 and paroxysmal nocturnal hemoglobinuria: The following drugs against C5a or C5aR1 are either currently available, have been withdrawn, or are in preclinical trials: 1) Eculizumab (Soliris®) is a humanized antibody against C5, approved for treatment of rare disorders (paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome).