An open label, randomized study to evaluate the effects of seven monophasic oral contraceptive regimens on hemostatic variables. Outline of the protocol. Oral Contraceptive and Hemostasis Study Group

Oral Contraceptives and Venous Thromboembolism: Focus on Testing that May Enable Prediction and Assessment of the Risk

Combined oral contraceptives (COCs) induce several changes in the levels of coagulation factors. The levels of procoagulant factors are often increased, while levels of anticoagulant factors are decreased. Fibrinolysis is also affected, even if the effect seems to be more counterbalanced by opposite regulation of profibrinolytic and antifibrinolytic factors. These effects on hemostasis are more pronounced with third- or fourth-generation COC compared with second-generation COC. Venous thromboembolism (VTE) risk increases when multiple risk factors, including genetic and environmental, are present simultaneously. COC use causes changes in coagulation that modify the prothrombotic state induced by preexisting hemostatic alterations in a supra-additive manner. Therefore, testing appears to be of importance not only before implementing COC but also to monitor any potential thrombogenicity induced by COC therapy. Inherited genetic factors, such as factor V Leiden, G20210A prothrombin mutation, antithrombin, protein C or protein S deficiencies, non-O blood group, as well as CYP2C9*2 and the rs4379368 mutations, have all been identified as genetic predictive risk factors of VTE in women. Nevertheless, the screening of these genetic biomarkers is not capable of assessing the phenotypic expression of the risk. This review will focus on the different options for screening the thrombogenic status in this population. Specific attention will be given to the endogenous thrombin potential-based activated protein C resistance, a test aiming at assessing the thrombogenicity induced by hormonal therapies and inherited or acquired thrombophilia.

Fibrin clot structure - pro-fibrinolytic effect of oral contraceptives in apparently healthy women

Fibrin metabolism is influenced by many factors. The velocity of fibrin formation, genetic polymorphisms, fibrinolytic features and the structure of the fibrin clot are determinants of fibrin turnover. Oral contraceptives (OCs) have significant impact on the haemostatic system, by increasing the concentration of coagulation factors, plasminogen and tissue plasminogen activator activity, and decreasing the concentration of haemostatic inhibitors. The present study addresses the influence of OCs on fibrin structure and fibrin metabolism. The study included 70 women treated with seven different OC-formulations. Blood was collected at baseline and after six months of OCs. The plasma concentration of fibrinogen, thrombin-antithrombin complex (TAT), plasminogen, plasmin-antiplasmin complex (PAP), D-Dimer and thrombin generation measures were determined. Fibrin structure measures and fibrin clot lysis not affected by the plasma concentration of plasminogen activators and inhibitors were determined. OCs increased the concentration of fibrinogen, TAT, plasminogen, PAP and D-dimer significantly and affected measures of thrombin generation (p<0.001). The maximal optical density of fibrin (p<0.001), the fibrin fibre density (p=0.03), fibrin fibre diameter (p=0.003), fibrin mass-length ratio (p<0.001) and lysis per hour (p<0.001) increased significantly upon OC-treatment. Lysis per hour was not correlated to the concentration of plasminogen. We conclude that the effect of OCs on the coagulation system is balanced by alterations in fibrin structure, facilitating clot lysis and contributing to the fibrinolytic susceptibility already present in women treated with OC. These alterations may counterbalance the OC-induced increased thrombin generation and reduced coagulation inhibitory potential, contributing to maintenance of the haemostatic balance in women receiving OCs.

Venous thrombosis and oral contraceptives: current status

The use of oral contraceptives is associated with an increased risk of venous thrombosis. It is now generally accepted that women who use oral contraceptives that contain so-called third-generation progestins (desogestrel or gestodene) are exposed to a twofold higher risk of venous thrombosis than women who use oral contraceptives that contain the second-generation progestin levonorgestrel. Coagulation studies demonstrated that oral contraceptives increase the plasma level of prothrombin, decrease the level of protein S and induce acquired activated protein C resistance. The changes in hemostatic parameters can explain why women who use oral contraceptives are exposed to an increased risk of venous thrombosis and why the risk is further increased in third-generation oral contraceptive users.

Direct chromogenic substrate immuno-capture activity assay for testing of factor VII-activating protease

BACKGROUND

The Marburg I (MRI) single nucleotide polymorphism (SNP) of the factor VII-activating protease (FSAP) gene has been associated with thrombophilia and atherosclerotic disease. PCR is used to detect the SNP. Also, the specific FSAP activity to cleave single-chain urokinase-type plasminogen activator (scu-PA) serves as a surrogate for PCR testing. Development of further assays is indicated in order to increase testing opportunities for future studies.

METHODS

A direct chromogenic substrate immuno-capture activity assay for FSAP (FSAP dcs activity assay) was established. Performance characteristics of the FSAP dcs activity assay were compared to the FSAP scu-PA activity assay.

RESULTS

The FSAP dcs activity assay detects FSAP activity from 25% to 150% of the norm. Total CVs ranged from 6% to 10% for FSAP wild type samples and 9%-18% for MRI samples. Correlation between the FSAP dcs and scu-PA activity assays was low (R=0.7). The FSAP dcs activity determined the presence of the MRI FSAP alloenzyme with a diagnostic sensitivity and specificity of 100% [95% confidence interval (CI): 89.6%-100%] and 96.2% (95% CI: 93.2%-97.4%), respectively, whereas the specific FSAP dcs activity increased specificity to 99.0% (95% CI: 97.2%-99.6%).

CONCLUSIONS

The specific FSAP dcs activity represents a reliable method for the detection of the FSAP MRI alloenzyme. Due to the limited correlation between the FSAP dcs and scu-PA activity assays, these different measurands may exhibit different utility in research and clinical applications. Thus, the FSAP dcs activity assay can represent a valuable complement or alternative for FSAP testing in future studies.

Effects of oral and transdermal hormonal contraception on vascular risk markers: a randomized controlled trial

OBJECTIVE

To compare the effects of oral and transdermal contraceptives containing similar hormone formulations on vascular risk markers.

METHODS

We conducted a randomized, investigator-blinded, crossover, clinical trial with 24 healthy women, aged 18-35 years, who received 2 months of transdermal or oral contraceptive, 2 months washout, then 2 months of the alternative medication. The transdermal contraceptive contained 0.75 mg ethinyl estradiol and 6 mg norelgestromin. The oral contraceptive contained 35 mcg ethinyl estradiol and 250 mcg norgestimate. Blood samples taken before and after each treatment were analyzed in batch for D-dimer, von Willebrand factor, factor VIII, total and free protein S, antithrombin, fibrinogen, C-reactive protein, and normalized activated protein C sensitivity ratio (nAPCsr) determined with two thrombin generation-based assays, the alpha2macroglobulin-thrombin end point method (alpha2M-IIa) and calibrated automated thrombinography. Repeated measures analysis of variance was used for analysis.

RESULTS

For both contraceptives (transdermal, oral) there were significant declines in free (19%, 11%) and total protein S (19%, 13%) and antithrombin (13%, 10%); increases in fibrinogen (8%, 10%), C-reactive protein (220%, 292%), nAPCsr alpha2M-IIa (81%, 61%), and nAPCsr calibrated automated thrombinography (102%, 68%), all P<.05. Transdermal contraceptives had a greater effect than oral contraceptives on free protein S (P=.07), nAPCsr alpha2M-IIa (P=.06), and nAPCsr calibrated automated thrombinography (P=.03).

CONCLUSION

Oral and transdermal contraception with similar hormones had similar adverse effects on vascular risk markers. This suggests that this transdermal contraceptive has at least a similar thrombosis risk as its oral counterpart.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, www.clinicaltrials.gov, NCT00554632

LEVEL OF EVIDENCE

I.

A prospective study on the effects on hemostasis of two oral contraceptives containing drospirenone in combination with either 30 or 20 microg ethinyl estradiol and a reference containing desogestrel and 30 microg ethinyl estradiol

PURPOSE

In this open-label, randomized study, we assessed the effects on hemostasis of two combined oral contraceptives containing drospirenone (DRSP) as progestogen component.

METHODS

Three milligrams of DRSP, a progestogen with antimineralocorticoid activity, was combined with either 30 or 20 microg ethinyl estradiol (EE) (DRSP/30EE; DRSP/20EE) and compared with a preparation containing 150 microg desogestrel (DSG) and 30 microg ethinyl estradiol (DSG/30EE). A total of 75 healthy female volunteers aged 18-35 years were enrolled. The hemostasis variables were measured in the medication-free precycle (baseline); in the first, third and sixth treatment cycle; and in the follow-up phase. The target variables for comparison were the relative changes from baseline to Cycle 6.

RESULTS

Data of 25 volunteers in each group were valid for the per-protocol evaluation. Most changes in hemostasis variables were similar in the three treatment groups. All procoagulatory variables and the anticoagulatory variable protein C antigen increased slightly, while protein S antigen and activity decreased. For fibrinogen and protein S activity, the changes were statistically significant: less pronounced with DRSP/20EE compared to DSG/30EE at Cycle 6. There were no statistically significant differences in the changes of antifibrinolytic variables, the global clotting tests and D-dimer. All pairwise comparisons of DRSP/30EE vs. DSG/30EE yielded nonsignificant results; however, there was a trend of a lower impact of DRSP/20EE on nearly all hemostatic parameters compared to the 30EE products. All three study treatments were safe and well tolerated by the volunteers and provided adequate contraceptive reliability.

CONCLUSION

The changes in the hemostatic variables for DRSP/20EE were less pronounced compared to DSG/30EE and DRSP/30EE. The results were in accordance with previous reports on effects of similar OCs.

A 1-year study to compare the hemostatic effects of oral contraceptive containing 20 μg of ethinylestradiol and 100 μg of levonorgestrel with 30 μg of ethinylestradiol and 100 μg of levonorgestrel

OBJECTIVES

To comparatively evaluate the impact of a balanced one-third dose-reduced oral contraceptive on hemostatic variables.

METHODS

In an open-label, randomized study, a dose-reduced oral contraceptive containing 20 microg of ethinylestradiol (EE) and 100 microg of levonorgestrel (LNG) was compared with a reference preparation containing 30 microg of EE and 150 microg of LNG. One-year data were obtained from 48 volunteers.

RESULTS

The direction and magnitude of the changes (increase or decrease) in most of the hemostatic variables were similar in both treatment groups. The majority of changes of all investigated variables remained within the reference ranges of variation. The procoagulatory variables increased to some extent from baseline to treatment cycle 13, while the anticoagulatory variables slightly decreased. In particular, thrombin turnover measured by prothrombin fragments 1+2 increased during treatment by 35% in the 20 microg of EE group and by 38% in the 30 microg of EE group. Statistically significant differences between the two treatment groups were found only for TAT. For the profibrinolytic variables, plasminogen was increased by 42% (20 microg of EE) and 49% (30 microg of EE). While the plasma levels of tPA antigen were reduced during treatment, the levels of its activity were increased by 54% (20 microg of EE) and 20% (30 microg of EE). For PAI, both antigen and activity were decreased, somewhat more pronounced with 20 microg of EE. D-Dimer remained virtually unchanged. Finally, the median FbDP levels were elevated by 30% (20 microg of EE) and 38% (30 microg of EE).

The effects of seven monophasic oral contraceptive regimens on hemostatic variables: conclusions from a large randomized multicenter study

We investigated the effects of ethinylestradiol dose (50, 30 and 20 microg) and progestogen type [desogestrel (DSG), gestodene (GSD), levonorgestrel (LNG) and norgestimate (NGM)] in oral contraceptives on 24 hemostatic variables. In a multicenter, randomized, comparative study, 707 healthy, nonsmoking, nulliparous women were treated for six cycles with one of the seven monophasic oral contraceptives tested. Significantly greater increases in prothrombin fragment 1+2 and factor VII (activity and antigen), were found in the DSG, NGM and GSD groups compared to the LNG group. Similarly, significantly lower levels of protein S (free and total) and increased APC-sr (endogenous thrombin potential based) were found in the same groups compared with the LNG group. In addition, the estradiol dose (50 vs. 30 microg) significantly influenced these parameters. All changes were within the normal range and have not been associated with an increased risk of venous thromboembolic event (VTE). However, raised levels of these variables are associated with prothrombotic states such as pregnancy. The significance of the haemostatic changes found in this study in relation to VTE risk remains to be determined, but results of this study probably cannot explain the differences in risk of VTE between OCs containing different progestogens.

A comparison of cycle control, efficacy, and side effects among healthy Thai women between two low-dose oral contraceptives containing 20 microg ethinylestradio1/75 microg gestodene (Meliane) and 30 microg ethinylestradio1/75 microg gestodene (Gynera)

The purpose of this study was to compare cycle control, efficacy and side effects of an oral contraceptive containing 20 microg ethinylestradiol and 75 microg gestodene, with a reference preparation containing 30 microg ethinylestradiol combined with 75 microg gestodene. From the study, it was demonstrated that the two regimens had no difference in cycle control, efficacy, and side effects. The occurrence of spotting and breakthrough bleeding was low and was not different between these two preparations. The most common adverse events in both treatment groups were nausea, vomiting, dizziness, and chloasma. There were no statistically significant change in body weight and blood pressure in both groups at the end of study. It is concluded that both preparations are good cycle control, reliable and low side effects oral contraceptives.

An open label, comparative study of the effects of a dose-reduced oral contraceptive containing 20 microg ethinyl estradiol and 100 microg levonorgestrel on hemostatic, lipids, and carbohydrate metabolism variables

In this open label, randomized study we compared the influence of a dose-reduced oral contraceptive containing 20 microg ethinyl estradiol (EE) and 100 microg levonorgestrel (20 EE) with a reference preparation containing 30 microg EE and 150 microg levonorgestrel (30 EE) on hemostatic, lipids, and carbohydrate metabolism variables. Data from 48 volunteers were obtained. The direction of the change (increase or decrease) in most of the hemostatic variables were similar in both treatment groups. In particular, prothrombin fragment 1 + 2 increased during treatment, reaching a median percent change of 40% in the 20 EE group and of 17% in the 30 EE group after one year. D-Dimer fibrin split products remained virtually unchanged, with no change at Cycle 13. The median HDL2 cholesterol levels decreased by 26% in the 20 EE group and by 39.8% in 30 EE group (p = 0.0045 for group difference) after one year. The median one year change for LDL cholesterol was 3.23% in the 20 EE group, compared to 25% in the 30 EE group, for VLDL 11.1% compared to 38.8%, respectively, and for total triglycerides 10.0% compared to 37.5%, respectively. The median absolute change for the area under the curve (AUC)(0-3h) for glucose at treatment Cycle 13 was 41.25 mmol/L x min in the 20 EE group and 73.50 mmol/L x min in the 30 EE group. The AUC(0-3h) insulin at treatment Cycle 13 decreased in the 20 EE group by 1635.0 pmolL x min and increased in the 30 EE group by 11797.5 pmolL x min (p = 0.0491 for group difference). Both study treatments were safe and well tolerated by the volunteers. In conclusion, the balanced one-third dose reduction in this new oral contraceptive evoked similar effects on the hemostatic variables, but favorable results for the lipid and carbohydrate profiles.

A double-blind comparative study of the effects of a 23-day oral contraceptive regimen with 20 microg ethinyl estradiol and 75 microg gestodene and a 21-day regimen with 30 microg ethinyl estradiol and 75 microg gestodene on hemostatic variables, lipids, and carbohydrate metabolism

In this double-blind study we compared the influence of two oral contraceptives, a 23-day regimen with 20 microg ethinyl estradiol and 75 microg gestodene (23-day 20/75) and a 21-day regimen with 30 microg ethinyl estradiol and 75 microg gestodene (21-day 30/75), on hemostatic variables, lipids, and carbohydrate metabolism. The volunteers received the preparations daily for six 28-day cycles. Hemostatic variables and lipids were measured at baseline and after six treatment cycles. Carbohydrate metabolism was assessed by determination of the area under the curve (AUC) of carbohydrate parameters after oral glucose tolerance tests performed at baseline and after three treatment cycles. Data from 33 volunteers in each group were obtained. No significant differences between the effects of both treatments on the hemostatic system were detected. Neither the overall change of all hemostatic variables from baseline to treatment Cycle 6 [defined as primary target variable in the study] nor the change of any of the individual hemostatic parameters differed significantly between the treatment groups. Likewise, no significant nor clinically relevant differences in the effects of both treatments on the volunteers' lipid profiles were detected. The data on carbohydrate variables suggested a slightly more favorable influence of the 23-day 20/75 regimen. The increase of the glucose AUCs after three cycles tended to be stronger with the 21-day 30/75 regimen than with the 23-day 20/75 regimen. In addition, the AUCs for insulin and C-peptide were slightly reduced after three cycles with the 23-day 20/75 regimen but slightly increased with the 21-day 30/75 regimen. Both study treatments were safe and well tolerated by the volunteers as shown by the nature and frequency of adverse events, the routine laboratory examinations, and the physical and gynecological examinations. Both preparations provided adequate contraceptive reliability. The only pregnancy during treatment was attributable to intake errors. In conclusion, the prolongation of the treatment phase of an oral contraceptives with 20 microg ethinyl estradiol does not evoke more pronounced metabolic effects than a conventional 21-day regimen with 30 microg ethinyl estradiol.

The emerging use of the 20-microg oral contraceptive

OBJECTIVE

To highlight studies that investigated the efficacy, safety, and tolerability of low-dose oral contraceptives (OCs) containing 20 microg of ethinyl estradiol (EE) and to discuss the use of these low-dose contraceptives in women from adolescence to menopause and the noncontraceptive health benefits likely to be afforded by low-dose contraceptives.

DESIGN

Relevant literature was identified by searching MEDLINE and EMBASE. Other sources were located by consulting the bibliographies of the material collected from Medline and EMBASE. Sources for additional information included documents from the United States Food and Drug Administration and the Physicians' Desk Reference (54th ed.).

CONCLUSION(S)

The current lowest available dose of EE used for OCs in the United States is 20 microg. Formulations with 20 microg of EE are efficacious and have a low incidence of estrogen-related side effects. Since this lowest effective EE dose inhibits ovarian activity, 20 microg of EE should also provide the noncontraceptive health benefits of OCs. Both contraceptive and noncontraceptive benefits of OCs are available to most women from adolescence to menopause without complications.

Occlusive vascular diseases in oral contraceptive users. Epidemiology, pathology and mechanisms

Despite being an unprecedented departure from normal physiology, the combined oral contraceptive is not only highly effective, but it also has a remarkably good safety record. Concerns over safety persist, though, particularly with regard to venous thromboembolism (VTE), stroke and myocardial infarction (MI). Epidemiological studies consistently show an increase in risk of VTE, but the results are more contentious with regard to arterial diseases. Despite 40 years of research, the mechanisms behind these adverse effects are not understood. In this review, we integrate information from published studies of the epidemiology and pathology of the occlusive vascular diseases and their risk factors to identify likely explanations for pathogenesis in oral contraceptive users. Oral contraceptives induce both prothrombotic and fibrinolytic changes in haemostatic factors and an imbalance in haemostasis is likely to be important in oral contraceptive-induced VTE. The complexity of the changes involved and the difficulty of ascribing clinical significance has meant that uncertainty persists. A seriously under-researched area concerns vascular changes in oral contraceptive users. Histologically, endothelial and intimal proliferation have been identified in women exposed to high plasma estrogen concentrations and these lesions are associated with thrombotic occlusion. Other structural changes may result in increased vascular permeability, loss of vascular tone and venous stasis. With regard to arterial disease risk, epidemiological information relating to dose effects and joint effects with other risk factors, and studies of pathology and changes in risk factors, suggests that oral contraceptive use per se does not cause arterial disease. It can, nevertheless, synergise very powerfully with subclinical endothelial damage to promote arterial occlusion. Accordingly, the prothrombotic effects of the oral contraceptive estrogen intervene in a cycle of endothelial damage and repair which would otherwise remain clinically silent or would ultimately progress - in, for example, the presence of cigarette smoking or hypertension - to atherosclerosis. Future work in this area should focus on modification of the effects of established risk factors by oral contraceptive use rather than modification of the supposed risk of oral contraceptive use by established risk factors. Attempts to understand vascular occlusion in oral contraceptive users in terms of the general features of VTE or with reference to atherosclerosis may be limiting, and future work needs to acknowledge that such occlusions may have unique features. Unequivocal identification of the mechanisms involved would contribute considerably to the alleviation of fears over vascular disease and to the development of even safer formulations.