RESUMO
In the present study the effect of oral contraceptive (OC) treatment on selected factors involved in the activation, i.e. circulating activated factor VII (cFVIIa), and in the inhibition of blood coagulation, i.e. plasma protein S activity and circulating thrombomodulin (cTM), were for the first time measured in OC users in a prospective study. Beside other coagulation variables, these parameters were measured during treatment with three low estrogen formulations containing different gestagen components (norgestimate, gestodene). During OC treatment increases in the activation markers prothrombin fragment F1 + 2 and D-Dimer were found, suggesting an increased activation of blood coagulation and fibrinolysis. Along with elevated plasma levels of FVII antigen, cFVIIa was also found increased in all three treatment groups, while inhibitory components of blood coagulation, plasma protein S activity and cTM, significantly and similarly decreased during treatment in all three treatment groups. We conclude that low dose estrogen pills induce similar changes in the plasma levels of main regulatory components of blood coagulation, despite differences in their gestagen components. Increased levels of activators and decreased activities of inhibitors may contribute to arterial and venous thrombotic complications seen in predisposed OC users.
PIP: The effect of oral contraceptive (OC) treatment on selected factors involved in the activation and inhibition of blood coagulation was measured in a prospectively randomized parallel-group centralized-center study. These were circulating activated factor VII (cFVIIa) as well as plasma protein S activity and circulating thrombomodulin (cTM). In addition to other coagulation variables these parameters were measured during treatment with 3 low-estrogen formulations containing different gestagen components (norgestimate, gestodene). 60 healthy women 19-37 years old were included. The women in Group I used Cileste tablets containing 35 mcg ethinyl estradiol (EE) and 250 mcg norgestimate (NG). Group II women used the 3-phase preparation Tri-Cileste containing EE and different doses of NG; and Group II women used the 3-phase preparation Triodena containing different doses of EE and gestodene (GS). 21 days on treatment were followed by 7 days off of treatment before the next cycle was started. Participants were treated for 6 cycles. Blood samples were obtained during the luteal phase before treatment and on days 18-22 of the 3rd and 6th treatment cycle. The plasma levels of various coagulation parameters, such as fibrinogen (Cileste, Tri-Cileste p 0.05; Triodena p 0.0005); fibrin-split product D-Dimer (Cileste p 0.05; Tri-Cileste, Triodena p 0.005), prothrombin fragment F1+2 (Cileste p 0.0005); Tri-Cileste, Triodena p 0.05); Factor VII antigen (Cileste, Triodena p 0.0005; Tri-Cileste p 0.005); FVII clotting activity (Cileste p 0.0005; Tri-Cileste p 0.05; Triodena p 0.005), and activated factor VII (Cileste p 0.0005; Tri-Cileste p 0.05; Triodena p 0.005) were significantly higher during the 3rd treatment cycle compared with the pretreatment values. A significant decrease was also found in the plasma levels of total and free protein S antigen (total protein S: Cileste p 0.05; Tri-Cileste, Triodena p 0.005; free protein S: Cileste, Tri-Cileste p 0.0005; Triodena p 0.05) and circulating thrombomodulin (Cileste p 0.05; Tri-Cileste p 0.0005; Triodena p 0.005).