Effects on hemostatic variables of desogestrel- and gestodene-containing oral contraceptives in comparison with levonorgestrel-containing oral contraceptives: a review

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.

Effects of low-dose combined oral contraceptives and protein S K196E mutation on anticoagulation factors: a prospective observational study

The association between low-dose combined oral contraceptives (COCs) and anticoagulation factors in Japanese women has been rarely studied. A total of 394 Japanese women with a new beginning cycle of COC use were enrolled, of whom 335 women visited the clinic within 4 weeks after starting the first cycle of COC. Visits occurred in the active phase (272 women) and the placebo phase (63 women). Free protein S (PS) antigen and activity levels and antithrombin activity levels decreased significantly in both the active and placebo phase groups. Protein C (PC) activity levels increased significantly in both groups. Larger reductions in free PS antigen and activity levels occurred with COC comprising either 30 µg ethinylestradiol/desogestrel or 20 µg ethinylestradiol/drospirenone than that comprising 35 µg ethinylestradiol/norethisterone. In four women with the Japanese-specific PS K196E mutation, mean PS activity was 65% before COC use and 57% during COC use, indicating further decrease with COC use. In conclusion, decreased antigen and activity levels of PS and antithrombin and increased activity levels of PC were observed even during the first cycle of low-dose COC use. The effects on PS and PC activities were also observed in the hormone-free interval.

Effects of conventional or extended-cycle regimen of an oral contraceptive containing 30 mcg ethinylestradiol and 2 mg dienogest on various hemostasis parameters

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.

Upper extremity deep vein thrombosis after suspension of progesterone-only oral treatment

The intake of steroid hormone contraceptives is a strong and independent risk factor for venous thromboembolism. Several studies have assessed an increased risk of venous thromboembolism in women using oral contraceptives who are carriers of the G20210A mutation in the prothrombin gene. Most trials evaluating the thrombotic risk of oral contraceptives are based on combined oral preparations, but only a few focus on progestogen-only oral preparations. Results from such studies are conflicting and globally assess the thrombotic risk, ranging from modest to slightly increased. Furthermore, little is known about the relationship between the C677T mutation in the methylenetetrahydrofolate reductase gene and the progestogen-based preparations. Herewith we report the case of a 49-year-old woman with a complex genetic thrombosis risk factor who had taken oral progesterone for 15 months without any complication, but then experienced severe left upper extremity deep vein thrombosis 2 months after the drug suspension.

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.

Oral contraceptives and DDAVP nasal spray: patterns of use in managing vWD-associated menorrhagia: a single-institution study

The purpose of this study was to examine patterns of use for oral contraceptive and desmopressin acetate nasal spray, both used in managing menorrhagia in adolescents with von Willebrand disease (vWD). Hospital records of adolescents with documented vWD and menorrhagia were reviewed retrospectively. Subjects with vWD type 1 (n = 36) administered either oral contraceptives (OC) or intranasal desmopressin acetate (DDAVP) and followed from 6 months to 4 years were selected for inclusion. Treatment outcomes were examined with respect to effectiveness and safety. Assessing menstrual blood loss using PBAC scores from pretreatment and treatment periods determined effectiveness. Safety was evaluated by monitoring reported adverse events. No significant differences were identified in treatment effectiveness for controlling menorrhagia in vWD adolescents in the OC and intranasal DDAVP group comparisons: 86% versus 77% (P > 0.05), respectively. When combining both treatment groups, the majority of vWD adolescents, 81% (P > 0.05), experienced alleviation of menorrhagia symptoms. Treatment failures were attributed to either the inability of a regimen to control bleeding or to adverse events, including severe headaches and flushing with DDAVP. Safety outcomes were not significantly greater in vWD patients with menorrhagia when OC were compared with intranasal DDAVP. Both medical approaches, OC and DDAVP nasal spray, used in managing menorrhagia in adolescents with documented type I vWD were well tolerated and showed equivalent effectiveness, and no serious adverse events were reported.

Effect of four oral contraceptives on hemostatic parameters

This is the first double-blind, controlled, randomized study comparing the effect of different estrogen components in oral contraceptives (OCs) on hemostasis variables. Four groups of 25 women each were treated for six cycles with monophasic combinations containing 21 tablets with either 30 microg ethinylestradiol (EE) + 2 mg dienogest (DNG) (30EE/DNG), 20 microg EE + 2 mg DNG (20EE/DNG), 10 microg EE + 2 mg estradiol valerate (EV) + 2 mg DNG (EE/EV/DNG) or 20 microg EE + 100 microg levonorgestrel (LNG) (EE/LNG). Blood samples were taken on Days 21-26 of the control cycle and on Days 18-21 of the first, third and sixth treatment cycle. Treatment with all four OCs caused an increase in levels of fibrinogen, prothrombin fragment 1+2, D-dimer, plasminogen, plasmin-antiplasmin complex and an increase in protein C activity, a decrease in antithrombin activity, tissue-plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI), and a slight decrease in the sensitivity to activated protein C, but no significant change in that of the thrombin-antithrombin complex. In users of the DNG-containing OCs, the reduction in total and free protein S, and in t-PA and PAI was dependent on the EE dose, while factor VII activity was elevated, but not significantly different from EE/LNG. The results are in agreement with those of previous studies. The effects of EE/EV/DNG on total and free protein S and on t-PA and PAI were lower than those of 20EE/DNG, suggesting that the impact of 2 mg EV on several hemostasis variables is less than that of 10 microg EE. The results show an antagonistic effect of LNG on the EE-induced rise of factor VII activity and fragment 1+2 and on the EE-dependent reduction of total and free protein S.

Differential effects of progestins on hemostasis

Recently large, prospective, randomized studies on hormone replacement therapy (HRT) have indicated that the progestin use might interfere with hemostasis and thus increase venous thrombotic events. Therefore, available publications were evaluated to determine whether progestins interfere with hemostasis, either when given alone via oral or parenteral routes or in combination with ethinylestradiol as synthetic estrogen or natural estrogens. There are indications that such interference is dependent upon the type and dose of the progestin, the route of application, the length of treatment and the type and dose of the estrogen with which it is combined. For natural progesterone, no negative effects on the hemostatic system were seen with either oral or parenteral application, in cyclic or continuous regimens, for the doses investigated. Similarly, no unwanted effects were seen with progestin only pills (POP), independent of the type and dose of progestin, or parenteral progestins. With the high-dose progestins used in gynaecological oncology, the increased activation of the hemostatic system resulting from the disease itself has to be taken into account when looking at any increased incidence of thromboembolic events in these patients. For estrogen/progestin combinations, the risk of venous thromboembolism is attributed to the estrogen used. Recent studies showed an increased rate of thromboembolic events in association with desogestrel-and gestodene-containing oral contraceptives, compared with those containing levonorgestrel. With HRT, a decrease in antithrombin factors could explain the increased rate of venous thrombotic events. In conclusion, progestins seems to have different effects on the hemostatic system due to their different pattern of biological activities. This was also shown in the arterial vascular system, where some progestins may reduce the endothelium-dependent vasodilating action of estrogens and stimulate intima proliferation and upregulate thrombin receptor expression while other progestins did not.

The contraceptive vaginal ring (NuvaRing®) and hemostasis: a comparative study

This open-label, nonrandomized study compared changes in hemostatic variables during NuvaRing and oral levonorgestrel 150 microg/ethinylestradiol 30 microg (LNG/EE) use for six cycles. Eighty-seven women started the study, 44 with NuvaRing and 43 with the LNG/EE oral contraceptive. For most procoagulation variables, there was no difference between NuvaRing and oral LNG/EE; only Factor VII levels increased in the NuvaRing group and decreased in the LNG/EE group. The majority of assessed variables show that anticoagulation and fibrinolytic activity was comparable between the NuvaRing and oral LNG/EE groups. Antithrombin activity and protein C activity both tended to be higher with NuvaRing. Levels of tissue plasminogen activator decreased in both groups but the reduction was smaller with NuvaRing. There were no significant differences in fibrin turnover between the treatment groups. The data show that both NuvaRing and oral LNG/EE are associated with a minimal effect on hemostatic variables.

Venous thrombosis and changes of hemostatic variables during cross-sex hormone treatment in transsexual people

The incidence of venous thrombosis associated with estrogen treatment in male-to-female (M-->F) transsexuals is considerably higher with administration of oral ethinyl estradiol (EE) than with transdermal (td) 17-beta-estradiol (E(2)). To find an explanation for the different thrombotic risks of oral EE and td E(2) use, we compared the effects of treatment of M-->F transsexuals with cyproterone acetate (CPA) only, and with CPA in combination with td E(2), oral EE, or oral E(2) on a number of hemostatic variables [activated protein C (APC) resistance and plasma levels of protein S, protein C, and prothombin], all of which are documented risk factors for venous thrombosis. APC resistance was determined by quantification of the effect of APC on the amount of thrombin generated during tissue factor-initiated coagulation; plasma levels of total and free protein S were determined by standard ELISA; and levels of prothrombin and protein C were determined with functional assays after complete activation of the zymogens with specific snake venom proteases. CPA-only, td-E(2)+CPA, or oral-E(2)+CPA treatment produced rather small effects on hemostatic variables, whereas oral EE treatment resulted in a large increase in APC resistance from 1.2 +/- 0.8 to 4.1 +/- 1 (P < 0.001), a moderate increase in plasma protein C (9%; P = 0.012), and a large decrease in both total and free plasma protein S (30%; P < 0.005). The large differential effect of oral EE and oral E(2) indicates that the prothrombotic effect of EE is due to its molecular structure rather than to a first-pass liver effect (which they share). Moreover, these differences may explain why M-->F transsexuals treated with oral EE are exposed to a higher thrombotic risk than transsexuals treated with td E(2). Testosterone administration to female-to-male transsexuals had an antithrombotic effect.

Comparative study of the effects of two once-a-month injectable contraceptives (Cyclofem® and Mesigyna®) and one oral contraceptive (Ortho-Novum 1/35®) on coagulation and fibrinolysis

A randomized controlled multicenter study was undertaken to monitor the effects on hemostasis of two once-a-month injectable contraceptive preparations, Mesigyna (50 mg norethisterone enanthate and 5 mg estradiol valerate) and Cyclofem (25 mg medroxyprogesterone acetate and 5 mg estradiol cypionate) in comparison with a well-known oral contraceptive (OC) Ortho-Novum 1/35 (norethisterone 1 mg and ethinyl estradiol 35 microg). A total of 378 volunteers from four centers (Bangkok, Hangzhou, Santiago and Singapore) were monitored. Blood sampling took place in one pretreatment cycle, the third and ninth injection intervals and one posttreatment cycle. In each of the three treatment groups, a rise in hemoglobin, and increases in platelet count and in prothrombin time were observed. With treatment there was a significant increase in activated partial thromboplastin time among Mesigyna users, no change among Cyclofem users and a significant decrease among OC users. OC use led to increases in plasma levels of fibrinogen, factor VII, factor X, plasminogen, protein C and decreases in plasma levels of t-PAI and antithrombin. Use of combined injectables induced no change (Cyclofem) or decreases (Mesigyna) in plasma levels of fibrinogen, factor VII, factor X and antithrombin. Use of both combined injectables led to decreases in protein C, slight decreases in plasminogen and increases in plasminogen and fibrinogen. Overall, the injectable preparations may be more beneficial than the oral preparation in not enhancing a hypercoagulable state because of the reduced synthesis of fibrinogen, factors VII and X; however, decreases in antithrombin and protein C, which are potent coagulation inhibitors, may raise some concern. Whether these changes can lead to modifications in the risk of arterial or venous disease can only be ascertained by conducting epidemiological studies.

Activated protein C resistance determined with a thrombin generation-based test predicts for venous thrombosis in men and women

Activated protein C (APC) resistance, determined with a thrombin-generation-based APC resistance test, may explain risk differences of venous thrombosis in users of second- and third-generation oral contraceptives (OC). To clinically validate this test, we analysed the Leiden thrombophilia case-control study (474 patients with a first episode of deep vein thrombosis and 474 age- and sex-matched control subjects). Data for men and women were analysed separately. As hormonal status in women is known to strongly influence the APC sensitivity ratio (APCsr), additional strata (OC use and menopausal state) were defined. The APCsr was higher in all patients than in control subjects. Odds ratios (OR), using the 90th percentile of all control subjects (APCsr > 4.5) as cut-off, were: 7.5 [95% confidence interval (CI) 1.6-33.8] for men, 3.0 (95% CI 1.0-8.8) for premenopausal women not using OC, 4.8 (95% CI 1.6-14.7) for premenopausal women using OC and 4.7 (95% CI 1.4-15.6) for postmenopausal women. After excluding the carriers of factor V Leiden, the OR became infinite for men (no control had an APCsr > 4.5), 1.4 (95% CI 0.2-8.2) for premenopausal women not using OC, 3.4 (95% CI 1.1-10.8) for premenopausal women using OC and 3.6 (95% CI 0.6-20.5) for postmenopausal women. A high APCsr, determined with the thrombin-generation-based APC resistance test, predicts venous thrombotic risk, in populations with and without factor V Leiden. In addition, acquired APC resistance resulting from OC use predicts an increased risk for venous thrombosis independent of factor V Leiden.

Thrombophilias and gynaecology

In gynaecology, women are exposed to sex steroids when using oral contraceptives, hormone replacement therapy or when undergoing in vitro fertilization treatment and ovulation induction. Oral contraceptives and the use of hormone replacement therapy increase the risk of venous thrombosis. The risk is highest in the first year of use and higher among women with clotting defects. Women taking third-generation oral contraceptives have an almost twofold increased risk of venous thrombosis compared with those taking second-generation oral contraceptives. Inherited clotting defects, which are themselves risk factors of venous thrombosis, (e.g. factor V Leiden mutation, deficiency of protein C, protein S or antithrombin, high plasma levels of factor VIII, and prothrombin mutation) appear synergistically increase the risk of venous thrombosis caused by oral contraceptives. Recent studies also point to an interaction between hormone replacement therapy and coagulation defects in causing venous thrombosis. Emerging studies show that in vitro fertilization treatment and ovulation induction are also risk factors for venous thrombosis; the role of coagulation defects in this association is not yet clear.

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.

Menorrhagia from a haematologist's point of view. Part II: management

The management of menorrhagia has until recently been the domain of the gynaecologist. As haematologists, we are now addressing the issue of optimal management of menorrhagia in our patients with bleeding disorders. Addressing three life periods, the menarche, reproductive years, and postchildbearing years, this review will discuss the use of oral contraceptive agents, antifibrinolytics, non-steroidal anti-inflammatory drugs, intranasal DDAVP and the new levonorgestrel-impregnated IUD. Management of specific bleeding disorders will also be reviewed for von Willebrand disease, haemophilia A and B carriers, women with factor XI deficiency and PAI-1 deficiency.

The mechanisms of thrombotic risk induced by hormone replacement therapy

OBJECTIVES

To review the available information on the action of hormones on the mechanisms involved in thrombotic risk.

RESULTS AND CONCLUSIONS

Thrombosis plays a crucial role in the genesis and progression of both coronary heart disease (CHD) and venous thromboembolic disease (VTED), the two main forms of cardiovascular disease. Two main determinants of the thromboembolic phenotype, hypercoagulable state and altered endothelium, accumulate much of the work performed on the influence of hormones on thrombosis. Information has accumulated mainly for oestrogens, but increasing evidences support a role for progestogens. The sensitivity of each of the three components of the hemostatic balance, the coagulation cascade, the anticoagulant system and fibrinolysis, to oestrogens has been widely examined in the literature. Functional tests suggest that HRT is accompanied by a procoagulant state. Much of the work has concentrated on changes induced on reputable indicators of risk for either CHD or VTED. Distinct indicators of increased coagulability, such as resistance to activated C protein, antithrombin or tissue factor pathway inhibitor have been selected for VTED, whereas factor VII, fibrinogen, and defective fibrinolysis, for CHD. Different states of genetic susceptibility have been involved in both forms of the disease. The status of health of endothelium, defines another scenario for attention in CHD. A long-term anti-atherogenic action of oestrogens, which may be associated with short-term risk in cases of atherosclerosis-induced endothelial dysfunction, may most adequately explain much of the clinical observation. In both CHD and VTED, the procoagulant changes initiate soon after HRT administration.

Activated protein C resistance during in vitro fertilization treatment

Acquired resistance to the anticoagulant action of activated protein C (APC) has been proposed to explain the increased risk of venous thrombosis associated with pregnancy, hormone replacement therapy and the use of oral contraceptives. In this study, we have investigated whether the hormonal changes induced during in vitro fertilization (IVF) treatment are also associated with acquired APC resistance. Twenty-nine women, who were planned for an IVF cycle, donated blood at four time points during treatment, i.e. at baseline, down-regulation, hyperstimulation and luteal support. In the plasma samples, APC sensitivity ratios (APCsr) and the levels of progesterone and estradiol were measured. The changes in plasma concentrations of hormones were in accordance with literature. The APCsr increased significantly during hyperstimulation and remained high during luteal support. The extent of APC resistance occurring during IVF treatment was comparable to that observed during the use of second generation OC and was less pronounced than that occurring during pregnancy. The change in estradiol between baseline and hyperstimulation correlated with the change in APCsr. Although this suggests that plasma estrogen levels are an important determinant for acquired APC resistance, it remains to be established which plasma proteins are responsible for estrogen-induced APC resistance.

Comparison of the lipoprotein, carbohydrate, and hemostatic effects of phasic oral contraceptives containing desogestrel or levonorgestrel

Desogestrel (DSG) is a less-androgenic progestogen than levonorgestrel (LNG). This difference in androgenicity may be responsible for observed differences in metabolic effects between oral contraceptive (OC) formulations containing almost equivalent estrogen doses but with either DSG or LNG as a progestogen. To test the hypothesis, a prospective 9-month randomized comparison of plasma lipids, glucose, insulin, hemostasis, and sex hormone binding globulin (SHBG) was conducted in 66 healthy women using phasic formulations of OCs containing either DSG (DSG-OC) or LNG (LNG-OC). The study results showed that SHBG increased 3-fold with DSG-OC and 2-fold with LNG-OC. DSG-OC increased HDL-C, HDL(2)-C and HDL(3)-C; LDL-C decreased transiently. LNG-OC decreased HDL(2)-C and increased HDL(3)-C; HDL-C was unchanged and LDL-C decreased transiently. Both formulations increased VLDL-C and triglycerides, more with DSG-OC, but apolipoprotein B levels increased equally. Apo A-I and A-II increased more with DSG-OC than with LNG-OC. Neither formulation altered Lp(a) or fasting glucose and insulin levels. Postprandially, both formulations decreased glucose and increased insulin responses, but to an equivalent degree. Both OCs slightly enhanced procoagulant and profibrinolytic parameters to the same extent except for internally compensating decreases in Factor V and protein S with DSG-OC. In summary, at almost equivalent estrogen doses, a phasic OC containing DSG compared with LNG has a less androgenic effect on lipoproteins and SHBG, similar effects on hemostatic parameters with lower protein S and factor V activity and equivalent effects on carbohydrate metabolism. The lipoprotein, SHBG, and protein S and factor V differences are likely due to the lesser androgenicity of DSG allowing for a greater expression of the dose of estrogen.

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.

Hemostatic effects of third- and second-generation oral contraceptives: absence of a causal mechanism for a difference in risk of venous thromboembolism

Some observational studies have found a difference in the risk of nonfatal venous thromboembolism (VTE) with low-dose, oral contraceptives (OCs) containing desogestrel (DSG) or gestodene (GSD) and those containing levonorgestrel (LNG). However, this does not agree with current pathophysiological concepts. This review compares all 17 comparative studies on the hemostatic effects of DSG/GSD- and LNG- or norgestimate (NGM)-containing OCs, and comments on two recent cross-sectional studies on the effects of third- and second-generation OCs on activated protein C (APC) sensitivity. In the comparative studies, the only difference in hemostatic parameters between DSG/GSD- and LNG- or NGM-containing OC users was a tendency towards higher factor VII (FVII) levels with DSG/GSD OCs. Differential effects on APC sensitivity were observed with the endogenous thrombin generation potential (ETP) assay, but not with the classical APC resistance test. FVII is not a risk marker for VTE, but is affected by dietary fat, estrogens and androgens and may interfere with the ETP assay. As no differences in established VTE risk markers were observed, there is no plausible reason for a differential risk of VTE with DSG/GSD- and LNG-containing OCs. In fact, the lack of differences with regard to established risk markers of VTE gives further support to the findings of the most recent epidemiological studies, which have not found any difference in the risk of VTE between third- and second-generation OCs.

Low-dose oral contraceptives and acquired resistance to activated protein C: a randomised cross-over study

BACKGROUND

We have reported previously that, compared with use of second-generation oral contraceptives, the use of third-generation oral contraceptives is associated with increased resistance to the anticoagulant action of activated protein C (APC). Owing to the cross-sectional design of that study, these observations may have been subject to unknown bias or uncontrolled effects of the menstrual cycle. We aimed to overcome these sources of bias by doing a cycle-controlled randomised cross-over trial.

METHODS

The response to APC in plasma was assessed in 33 women who received two consecutive cycles of a second-generation oral contraceptive (150 microg levonorgestrel and 30 microg ethinyloestradiol) or a third-generation oral contraceptive (150 microg desogestrel and 30 microg ethinyloestradiol), and who switched preparations after two pill-free cycles. Normalised APC sensitivity ratios were calculated by measurement of the effect of APC on thrombin generation in the plasma of these women and in pooled plasma from 90 controls.

FINDINGS

Of the 33 women, five were excluded because not all required plasma samples were available. In the remaining 28 women, the normalised APC sensitivity ratio increased during treatment with both preparations. Compared with levonorgestrel, desogestrel-containing oral-contraceptive treatment caused a highly significant (p<0.0001) additional increase in normalised APC sensitivity ratio (0.51 [95% CI 0.37-0.66]). Normalised APC sensitivity ratios during oral-contraceptive treatment correlated with the values before oral-contraceptive use.

INTERPRETATION

Oral-contraceptive treatment diminishes the efficacy with which APC down-regulates in-vitro thrombin formation. This phenomenon, designated as acquired APC resistance, is more pronounced in women using desogestrel-containing oral contraceptives than in women using levonorgestrel-containing preparations. Whether acquired APC resistance induced by oral contraceptives explains the increased risk of venous thromboembolism in oral-contraceptive users remains to be established.

The effects of a low-dose monophasic preparation of levonorgestrel and ethinyl estradiol on coagulation and other hemostatic factors

OBJECTIVE

This study was undertaken to evaluate the effects on hemostatic factors of a low-dose preparation of levonorgestrel and ethinyl estradiol in a 12-cycle study.

STUDY DESIGN

Thirty healthy women began taking 100 microg levonorgestrel and 20 microg ethinyl estradiol on the first day of the menstrual cycle, continued to take the preparation for the next 21 days, and then took placebo for 7 days. Mean changes in prothrombin time, partial thromboplastin time, and levels of factors VII and X, antithrombin, plasminogen, fibrinogen, protein S, thrombin-antithrombin complexes, and D-dimer were analyzed at baseline and at cycles 3, 6, and 12 with paired Student t tests.

RESULTS

Factor X, plasminogen antigen and activity, and D-dimer levels were significantly increased (P </=.01) during all 3 cycle periods. Antithrombin antigen and protein S total antigen levels were significantly (P </=.001 ) decreased at cycles 3, 6, and 12, whereas factor VII and protein S activity levels were significantly (P </=.05) decreased at cycle 3 and at cycles 3 and 6, respectively.

CONCLUSION

The effects on hemostatic factors in healthy women of a monophasic preparation of 100 microg levonorgestrel and 20 microg ethinyl estradiol were similar to those of other low-dose oral contraceptives.