A comparative study of the hemostatic effects of two monophasic oral contraceptives containing 30 mu(g) ethinylestradiol and either 2 mg chlormadinone acetate or 150 mu(g) desogestrel.

OBJECTIVES

To determine the effect of two low-dose monophasic oral contraceptives containing either 2 mg chlormadinone acetate or 150 microg desogestrel on blood clotting and fibrinolysis.

METHODS

In vivo markers of intravascular coagulatory and fibrinolytic activity were measured in 45 volunteers randomly assigned to a 6-month treatment with one of the two study preparations.

RESULTS

During oral contraceptive use, the procoagulatory activity increased (increased prothrombin fragment 1+2), the anticoagulatory capacity changed (increased protein C activity, decreased activated protein C sensitivity, decreased protein S activity and decreased antithrombin III activity) and the fibrinolytic system was activated (increased concentrations of plasmin-antiplasmin complexes and D-dimer as well as total fibrin degradation products). There were no relevant differences between the two medication groups.

CONCLUSION

Our results demonstrate that both oral contraceptive preparations have comparable effects on the hemostatic system. There was a shift towards a new equilibrium of hemostatic activities, both coagulatory and fibrinolytic, at a higher turnover rate. Changes did not exceed the range of normal variation and were comparable to the published effects of other low-dose oral contraceptives. There was no evidence ofa differential risk of deep vein thrombosis between the two preparations.