ETHINYLESTRADIOL-20 VERSUS 30-MU-G COMBINED WITH 150-MU-G DESOGESTREL- A LARGE COMPARATIVE-STUDY OF THE EFFECTS OF 2 LOW-DOSE ORAL-CONTRACEPTIVES ON THE HEMOSTATIC SYSTEM

In a 6-month, randomized, double-blind study the effects of two combin ed oral contraceptives containing 150 mu g desogestrel and either 20 o r 30 mu g ethinylestradiol on hemostatic parameters were investigated in 1633 healthy women. Compared with baseline, the 30 mu g ethinylestr adiol formulation increased prothrombin fragment 1+2 (+72.2%), D-dimer (+42.4%) and protein C activity (+6.1%), whereas antithrombin-III act ivity (-6.3%) and protein S activity (19.7%) were decreased. The use o f the 20 mu g ethinylestradiol formulation was associated with the sam e pattern of changes, but with lowe magnitude (F1+2+61.1%, D-dimer+36. 0%. antithrombin III-5.3%, protein C+4.6% and protein S-16.0%). the ch anges from baseline were significantly smaller in the 20 mu g ethinyle stradiol group for D-dimer, antithrombin III and protein S than in the 30 mu g ethinylestradiol group (p=0.019, p=0.038 and p=0.001, respect ively). One women with a combined deficiency of proteins C and S devel oped deep venous thrombosis while using the 20 mu g ethinylestradiol f ormulation. Use of both formulations was associated with a shift of th e coagulation-fibrinolysis balance to an enhanced fibrin-generating an d fibrin-degradating activity. The less-pronounced effect on hemostasi s with the 20 mu g ethinylestradiol preparation is reassuring with reg ard to thromboembolic risk in general. However, women with coagulation inhibitor deficiency should be advised not use oral contraceptives.