In a double-blind controlled study on 45 rheumatoid arthritis patients, no effect of tranexamic acid (Cyklocapron, 4.5 g per day for 6 weeks) was found in terms of subjective or objective parameters of disease activity. Tranexamic acid did not reduce complement activation, measured by plasma concentrations of the complement C3 split product C3d. Immune complex concentrations in serum were also
unaffected. We conclude that plasmin inhibitors do not reduce immune complex mediated complement activation, and they should not be used for treatment of rheumatoid arthritis.