Disclosed is a method for producing a concentrated antibody solution comprising greater than 100 mg/mL of an anti-C5 antibody, the method comprising: providing a first aqueous solution comprising an anti-C5 antibody, the first aqueous solution having a first formulation and comprising no more than 50 mg/mL of the anti-C5 antibody subjecting the first aqueous solution to diafiltration to thereby produce a second aqueous solution, wherein the second aqueous solution has a second formulation as a result of the diafiltration and concentrating the second aqueous solution to produce a concentrated antibody solution comprising greater than 100 mg/mL of the anti-C5 antibody.
