Background: The study was conducted to investigate the effect of a combined oral contraceptive (COC) containing 30 mcg ethinylestradiol and 2 mg dienogest with two different regimens on various hemostasis variables.
Study design: Hemostatic parameters were measured in 59 women treated with a monophasic COC containing 30 mcg ethinylestradiol and 2 mg dienogest (EE/DNG) either conventionally (13 cycles with 21 days of treatment+7 days without hormones) or with an extended-cycle regimen (4 extended cycles with 84 days of continuous administration of EE/DNG, followed by a hormone-free interval of 7 days). Blood samples were taken on Days 21-26 of the preceding control cycle and on Days 19-21 of the 3rd and 13th conventional cycle or on Days 82-84 of the first and fourth extended cycle.
Results: After 3 and 12 months, significant increases in fibrinogen (20%), factor VII antigen (50-60%), factor VII activity (45%), activated factor VII (30-45%) and factor VIII activity (10-20%) occurred in both treatment regimens. In both groups, there was a small but significant decrease in the level and activity of antithrombin, a 20-25% decrease in total and free protein S and a 15-20% rise in the level and activity of protein C, but no significant change of the thrombin-antithrombin complex. A significant over-time rise by about 25% of prothrombin fragment 1+2 occurred only in the extended-cycle group, but this effect did not differ significantly from that observed during conventional treatment. Plasminogen was elevated by 50% in both groups, while tissue-plasminogen activator (t-PA) activity rose by 15% in the conventional group and by 25-30% in the extended-cycle group. In both groups, t-PA antigen was reduced by about 30% and plasminogen activator inhibitor-1 by 40-60%. The levels of the plasmin-antiplasmin complex rose by 30-40% and those of D-dimers by 20-55%. The prothrombin time was slightly increased and the activated partial thromboplastin time was slightly decreased.
Conclusion: In general, these results were in agreement with those observed during treatment with other COCs. The study demonstrated that during conventional and extended-cycle treatment with EE/DNG, a steady-state in the effects on hemostasis variables was reached within 3 months, and that the effects observed after 3 and 12 months of treatment did not substantially differ between conventional and extended-cycle regimen.