Importance of levonorgestrel dose in oral contraceptives for effects on coagulation

Effects of two different low-dose oral contraceptives on plasma homocysteine levels

OBJECTIVE

The aim of this study was to investigate the effects of two currently used low-dose combined oral contraceptives (COCs) (20 μg ethinyl estradiol [EE]/150 μg desogestrel [DSG] vs. 20 μg EE/100 μg levonorgestrel [LNG]) on plasma homocysteine levels.

METHODS

A total of 90 participants were enrolled in the study; 30 of them had not been using COC for at least 12 months prior to their enrollment, while 60 were on regular treatment within 12-18 months. Therefore, the control group consisted of 30 participants. Group DSG/EE consisted of 30 women and group LNG/EE consisted of 30 women. Serum samples of homocysteine profile were obtained during the early follicular phase.

RESULTS

Significantly lower serum homocysteine concentrations (Group DSG/EE: 7.2 +/- 1.3; Group LNG/EE: 9.1 +/- 3.2;

CONTROL GROUP

8.2 +/- 2.2; p<0.05) were observed in DSG/EE group compared to LNG/EE and control groups.

CONCLUSION

Although the decrease in homocysteine levels with 20 μg EE/150 μg DSG containing COC was statistically significant, the clinical relevance of our findings needs to be further investigated.

Effects of hormone treatment on hemostasis variables

A survey was made of the changes in hemostasis and related inflammatory biomarkers for hormone treatments (HT) of women. Treatments included were oral and non-oral estrogens combined or not with progestogens, raloxifene, tamoxifene, tibolone and ethinylestradiol in oral contraceptives with non-androgenic progestogens. Special attention was given to dosages lower than the present standard dose and we explored how treatment variants approached a situation of minimal changes in biomarkers. For oral unopposed estrogens, dose reduction effectively reduced the changes in some hemostasis markers, but not in a specific set of anticoagulant variables (antithrombin, protein S, tissue factor pathway inhibitor, and the endogenous thrombin potential assay for resistance to activated protein C). Inflammation markers from the liver showed a dose-dependent reduction but effects were not nullified at the lowest dose tested. It was concluded that adequate reduction of estrogen dose for these effects will coincide with the dose-range of efficacy. Androgenic progestogens may be suitable for further reducing the impact of estrogens on some of the anticoagulant variables; reductions of estrogen-induced C-reactive protein increases appear possible with specific progestogens (medroxyprogesterone actate, nomegestrol acetate). For non-oral unopposed estrogens, all variables except inflammation biomarkers from the vascular wall showed minimal changes. Reduction in vascular inflammatory biomarkers, considered to mark anti-inflammatory effects, is augmented by medroxyprogesterone actate or norethisterone acetate. It was concluded that unopposed, non-oral estrogen treatment is the present best available option approaching minimal effects of treatment on biomarkers. Progestogen selection requires more data. We postulated that minimal effects on all cardiovascular biomarkers should define the HT with maximal safety for venous and arterial vascular events. The survey has identified specific biomarkers sensitive to low-dose unopposed and opposed estrogen which can be used to characterize future preparations for HT.

The effect of medroxyprogesterone acetate on estrogen-dependent risks and benefits--an attempt to interpret the Women's Health Initiative results

The results of the two arms of the Women's Health Initiative (WHI) study allow a comparative assessment of the contribution of the progestogen component to the changes in risk of cardiovascular disease and cancer during treatment of postmenopausal women with conjugated equine estrogens and medroxyprogesterone acetate (CEE/MPA). However, the high proportion of older and overweight or obese women compromises any conclusions, since we estimate that 50% of the women would have the metabolic syndrome. In overweight postmenopausal women with hyperinsulinemia, the risk of breast cancer is elevated and cannot be increased further by hormone replacement therapy (HRT). Therefore, the non-significant, but consistent reduction in breast cancer risk during treatment with CEE alone might be based on an improvement of hyperinsulinemia. The 24% increase in breast cancer risk in the CEE/MPA group can be regarded as an artifact due to very low numbers of breast cancer diagnoses in the placebo group of women who had received HRT prior to the WHI study. The elevated risk of venous thromboembolism and the transient increase in the risk of coronary heart disease (CHD) during treatment with CEE/MPA but not CEE alone suggests a direct effect of MPA on the vessel wall. MPA has been demonstrated to upregulate the thrombin receptor, the thrombin-induced production of tissue factor and procoagulatory activity in the vessel wall owing to its glucocorticoid activity. In contrast, CEE alone reduced non-significantly the risk of CHD in women aged 50-59 years, suggesting that primary prevention is possible if estrogen replacement therapy is initiated early. As clinical studies on the effect of different progestogens combined with estrogens are scarce, a possible superiority of progestogens other than MPA remains to be proven.

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.

Pharmacology of estrogens and progestogens: influence of different routes of administration

This review comprises the pharmacokinetics and pharmacodynamics of natural and synthetic estrogens and progestogens used in contraception and therapy, with special consideration of hormone replacement therapy. The paper describes the mechanisms of action, the relation between structure and hormonal activity, differences in hormonal pattern and potency, peculiarities in the properties of certain steroids, tissue-specific effects, and the metabolism of the available estrogens and progestogens. The influence of the route of administration on pharmacokinetics, hormonal activity and metabolism is presented, and the effects of oral and transdermal treatment with estrogens on tissues, clinical and serum parameters are compared. The effects of oral, transdermal (patch and gel), intranasal, sublingual, buccal, vaginal, subcutaneous and intramuscular administration of estrogens, as well as of oral, vaginal, transdermal, intranasal, buccal, intramuscular and intrauterine application of progestogens are discussed. The various types of progestogens, their receptor interaction, hormonal pattern and the hormonal activity of certain metabolites are described in detail. The structural formulae, serum concentrations, binding affinities to steroid receptors and serum binding globulins, and the relative potencies of the available estrogens and progestins are presented. Differences in the tissue-specific effects of the various compounds and regimens and their potential implications with the risks and benefits of hormone replacement therapy are discussed.

A 1-year randomized study to evaluate the effects of a dose reduction in oral contraceptives on lipids and carbohydrate metabolism: 20 microg ethinyl estradiol combined with 100 microg levonorgestrel

OBJECTIVES

To evaluate the impact on lipid and carbohydrate variables of a combined one-third ethinyl estradiol (EE)/levonorgestrel (LNG) dose reduction in oral contraceptives.

METHODS

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

RESULTS

We found a decrease of HDL2 cholesterol and increases of low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol and total triglycerides in both treatment groups from baseline to the 13th treatment cycle. Although for four of six variables, the changes in the 20 EE group were lower compared with the 30 EE group, none of the differences between the two treatments were statistically significant. The median values for the fasting levels of insulin, C-peptide and free fatty acids slightly increased or remained unchanged while the fasting glucose levels slightly decreased after 13 treatment cycles. While the glucose area under the curve (AUC) (0-3 h) was similar in both groups during the OGTT, the insulin AUC(0-3 h) was less increased in the 20 EE/100 LNG group compared with the 30 EE/150 LNG group. None of the differences between the treatment groups for any of the carbohydrate metabolism variables were statistically significant at any time point. Both study treatments were safe and well tolerated by the volunteers.

CONCLUSION

Similar effects on the lipid and carbohydrate profiles were found for both preparations. The balanced one-third EE dose reduction in this new oral contraceptive caused slightly lower, but insignificant, changes in the lipid and carbohydrate variables compared with the reference treatment.

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).

Impact of progestagens on activated protein C (APC) resistance among users of oral contraceptives

Oral contraceptive (OC) use is associated with an increased risk of venous thromboembolism. Previous data reported higher thrombotic risk in women using third-generation combined OC than in those using second generation OC. The difference could be explained by differential effects of progestagens on plasma sensitivity to activated protein C (APC). The main purpose of this cross-sectional study was to assess the influence of a progestagen-only OC (chlormadinone acetate) as well as the effect of several combined OC with different progestagen components on APC resistance. The effect of APC on endogenous thrombin potential (ETP) was investigated in the plasma of healthy women using either combined OC (n=82) or progestagen-only OC (n=28), and in non-users (n=64). Carriers of factor V Leiden were excluded. Compared with non-users, there was no significant change in APC resistance in women using progestagen-only OC. Women who used combined OC were less sensitive to APC than non-users (P < 0.001) and the difference was significantly more pronounced in women using third-generation OC (n=41) than in those who used second-generation OC containing levonorgestrel (n=22) (P < 0.05). Compared with OC containing levonorgestrel, use of norethisterone-containing OC (n = 9) was associated with an increased resistance to APC (P < 0.05). Women who used cyproterone-containing OC (n = 10) were less sensitive to APC than those using third-generation OC (P < 0.05) or second-generation OC containing levonorgestrel (P < 0.05). Protein S, factor II and FVIII levels explained in part the OC-related changes in APC sensitivity variations. ETP-based APC resistance may contribute to explain why different brands of OC can be associated with different levels of thrombogenicity.

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.

Mechanisms of sex steroids

The discussion on the risks of hormone therapy supports the search for alternative drugs such as selective estrogen receptor modulators (SERMs). These compounds are suitable for special preventive goals, but cannot be expected to replace the use of estrogens in patients with estrogen deficiency. The development of selective progesterone receptor modulators (SPRMs) which has to resolve various problems, might be a promising approach. Hormone replacement therapy (HRT) with natural estrogens remains the measure of choice for treatment of symptoms caused by estrogen deficiency. Recent findings suggest that the additional progestogen which is used for the protection of the endometrium, plays a crucial role with regard to the risk of breast cancer and cardiovascular disease. As surrogate parameters cannot predict the extent of risks, suitable tools for the selection of progestogens with the least potential for causing adverse effects, are urgently needed. Experimental, clinical and epidemiological data suggest that the elevation in breast cancer risk is due to the proliferative effect of estrogens on breast tissue which is largely enhanced by progestogens. A short-term in vivo-test might be helpful for the evaluation of proliferative effects of estrogen-progestogen preparations. Similarly, a strictly standardized in vivo-test for the assessment of the atherogenic potential of estrogen-progestogen preparations might help to select the preparations with the lowest risk for ischemic diseases. The available data suggest that it is probably not the androgenic but the glucocorticoid activity of a progestogen which plays a role in the development of cardiovascular disease. Progestogens with glucocorticoid effects may up-regulate the thrombin receptor in the vessel wall which is involved in the development of atherosclerosis and stimulation of extrinsic coagulation.

Effect of second- and third-generation oral contraceptives on the protein C system in the absence or presence of the factor VLeiden mutation: a randomized trial

A plausible mechanism to explain thrombotic risk differences associated with the use of second- and third-generation oral contraceptives (OCs), particularly in carriers of factor V(Leiden), is still lacking. In a double-blind trial, 51 women without and 35 women with factor V(Leiden) were randomized to either a second- (30 microg ethinylestradiol/150 microg levonorgestrel) or third- (30 microg ethinylestradiol/150 microg desogestrel) generation OC. After 2 cycles of use and a wash-out of 2 cycles, the participants continued with the corresponding progestagen-only preparation. Hemostatic variables that probe the activity of the anticoagulant protein C system were determined. Compared with levonorgestrel, desogestrel-containing OCs significantly decreased protein S and increased activated protein C (APC) resistance in both groups. OCs with desogestrel had the most pronounced effects in carriers of factor V(Leiden). Progestagen-only preparations caused changes of anticoagulant parameters opposite to those of combined OCs, which in a number of cases were more pronounced with levonorgestrel. Our data show that progestagens in combined OCs counteract the thrombotic effect of the estrogen component. The higher thrombotic risk associated with third-generation OCs compared with second-generation OCs may be explained by the fact that desogestrel appeared less antithrombotic than levonorgestrel, especially in women with 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.

The association between extrinsic activated protein C resistance and venous thromboembolism in women

Recently, discussions have focused on the question of whether acquired APC resistance (APCsr) is a clue to the observed association between risk of venous thromboembolism (VTE) and OC use especially with the so-called third-generation OCs. It seems plausible that abnormalities in an extrinsic-based APCsr reflect an increased risk of VTE in women, but this has not yet been properly studied. The objective of our study was to determine whether there was an association of extrinsic APC resistance with VTE risk in a case-control study. Sixty-seven women with confirmed VTE diagnosis were consecutively recruited in primary health care settings, interviewed and blood samples were taken at least 6 months after VTE. Cases were age-matched to 290 population controls. Extrinsic APC resistance was measured as normalized APC ratio (APCsr). The effect of APC on tissue factor-initiated thrombin generation was measured in plasma using alpha2-macroglobulin attached thrombin activity as an endpoint. The extrinsic APCsr was significantly associated with factor V Leiden (FVL) mutation, both in the cases and in the controls. Also, in the women using OC, significantly higher values of APCsr were observed, which confirms the results of other studies. We did not identify a significant association between the extrinsic APCsr and VTE in women not using OC who are non-carriers of factor V Leiden using different approaches: comparison of medians, analyses with unconditional logistic regression using various cut-points of the APCsr distribution, and the comparison between the highest and the lowest quartile of APCsr. With all attempts, the risk estimates were close to unity. In conclusion, we were not able to find evidence for any association of extrinsic APCsr with VTE in women who were not using OCs and non-carriers of FVL.

Effect of dienogest-containing oral contraceptives on lipid metabolism

In a double-blind, controlled, randomized, four-arm, bicentric clinical study, the effect of four oral contraceptives (OCs) on lipid metabolism was investigated. Four groups composed of 25 volunteers each (mean age 26.1 +/- 4.5 years; body mass index 21.9 +/- 2.8 kg/m(2)) were treated for six cycles with monophasic combinations containing 21 tablets with either 30 microg ethinyl estradiol (EE) + 2 mg dienogest (DNG) (30 EE/DNG), 20 microg EE + 2 mg DNG (20 EE/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). The study was completed by 91 women. Blood samples were taken by venipuncture after at least 12 h fasting on Days 21-26 of the control cycle and Days 18-21 of the first, third, and sixth treatment cycle. There were clear differences between the effects of EE/LNG and the formulations containing estrogens and DNG. Although EE/LNG did not change the triglycerides levels, a significant increase was observed during treatment with the DNG-containing preparations. Although EE/LNG significantly reduced HDL-CH and HDL(2)-CH, there was a nonsignificant increase with the DNG-containing OCs. No change was observed in the levels of HDL(3)-CH. A significant rise in apolipoprotein A1 occurred during intake with the three DNG-containing formulations, but not with EE/LNG. In contrast to the women treated with combinations of estrogens and DNG, apolipoprotein B rose significantly in the women in the EE/LNG group. Lipoprotein (a) was significantly reduced by 30 EE/DNG and EE/LNG and remained unaltered with 20 EE/DNG and EE/EV/DNG. Altogether, the changes in lipid metabolism caused by the DNG-containing formulations appeared to be more favorable than those observed with EE/LNG. In OCs with DNG, the EE dose does not seem to play a major role with respect to the effect on lipids.

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.

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.

Oral contraceptive pills: considerations for the adolescent patient

Combined oral contraceptive pills (OCPs) are the most commonly prescribed method of birth control for adolescents. This article presents an overview of OCP pharmacology and summarizes the different types of OCPs. The initial patient evaluation and subsequent care are described, with a focus on management plans specific to adolescents. Emergency contraception, an alternative use of OCPs, is described as well. A thorough knowledge of OCPs and an appreciation of adolescent-specific management plans will enhance nurse practitioners' skills in preventing pregnancy in their adolescent patients.

Cardiovascular events associated with different combined oral contraceptives: a review of current data

Studies of combined oral contraceptive (COC) use and cardiovascular disease have been conducted against a background of low cardiovascular risk in young women, changing COC composition and changing user selection and monitoring. Studies of myocardial infarction have found inconsistent results, possibly because of differences in the prevalence of risk factors (particularly smoking and raised blood pressure) in the populations studied. In the absence of a history of smoking and other conventional risk factors, current users of modern COCs probably do not have an increased risk of myocardial infarction. Neither are former users at risk. Evidence for important differences in the risk of myocardial infarction between formulations is weak and contradictory. Current users of low estrogen dose COCs have a small increased risk of ischaemic stroke although most of the risk occurs in women with other risk factors (notably smoking, hypertension and probably a history of migraine). Former users of COCs do not have an increased risk of ischaemic stroke. There is insufficient information to determine whether major differences in the risk of ischaemic stroke exist between products. Current users appear to have a modestly elevated risk of haemorrhagic stroke, mainly in women older than 35 years; former users do not. Data examining the risk of haemorrhagic stroke in current COC users with other risk factors are very sparse, as are those relating to the haemorrhagic stroke risk associated with particular COCs. Numerous studies have found, with remarkable consistency, an elevated risk of venous thromboembolism among current users of low estrogen dose COCs. The risk is substantially elevated among women with various inherited clotting factor defects. The effects in COC users with other risk factors for venous thrombosis tend to be less pronounced and more inconsistent. A number of studies have found higher relative risks among current users of low estrogen dose COCs containing desogestrel or gestodene, than among users of similar products containing levonorgestrel. A number of explanations, in terms of bias or confounding, have been proposed for these clinically small differences. At best, empirical evidence for these explanations, is weak. The risk of cardiovascular disease of any description is low in COC users. Women can minimise, and possibly eliminate entirely, their arterial risks by not smoking and by having their blood pressure checked before using a COC (in order to avoid its use if raised blood pressure is discovered). Users may decrease their venous thromboembolic risk by their choice of COC preparation although the effects will be modest.