Elimination of inhibition in euglobulin fibrinolysis by use of flufenamate: involvement of C1-inactivator.

The fibrinolytic activity of euglobulin fractions prepared from human morning plasma and assayed on fibrin plates is strongly inhibited by the C1-inactivator present in the fractions. Flufenamate, a potent representative of the group of synthetic thrombolytic agents, eliminates this inhibition in euglobulin fractions. This elimination is an apparently irreversible reaction dependent on concentration, time and temperature. The fibrinolytic enhancing effect of flufenamate in euglobulin fractions correlated well with a similar effect of added C1s, which neutralized the C1-inactivator. The effect of flufenamate was slightly greater than that of added C1s, suggesting an additional effect of the flufenamate. The activity enhancing effect of the flufenamate at the lower molarities could be separated from an activity decreasing effect at the higher molarities. A simple technique by which inhibitory effects in euglobulin fibrinolysis are selectively eliminated is described.