EFFECTS OF LONG-TERM GESTODENE-CONTAINING ORAL-CONTRACEPTIVE ADMINISTRATION ON HEMOSTASIS

The purpose of this study was to evaluate the behavior of the hemostatic system during treatment with gestodene-containing oral contraceptives in monophasic (SHD 356, n = 15) and triphasic (SHD 415, n = 15) formulations. No changes in platelet (β-thromboglobulin, platelet aggregate ratio, and megathrombocyte) and routine clotting assays were observed. Factor VIIc/factor VIIag ratio and fibrinopeptide A values showed a significant (p < 0.005) increase after three cycles of both treatments. A slight, significant increase (p < 0.01) in antithrombin III activity was observed during triphasic treatment. Protein C was unchanged. Fibrinolytic activity and plasminogen levels were significantly increased (p < 0.05 and p < 0.001). After 6 and 9 months, the factor VIIc/factor VIIag ratio was still significantly enhanced, whereas fibrinopeptide A values significantly (p < 0.05) decreased, even if they were higher (p < 0.05) than basal values. The persistence of factor VII activation without enhanced thrombin formation after long-term use of oral contraceptives suggests that at that time the activity of antithrombotic mechanisms counteracts the prothrombotic tendency, thus helping to minimize unwanted side effects on hemostasis during long-term drug administration. © 1990.