Enhancement by factor V Leiden mutation of risk of deep-vein thrombosis associated with oral contraceptives containing a third-generation progestagen

Clinical utility of factor V leiden (R506Q) testing for the diagnosis and management of thromboembolic disorders

OBJECTIVE

To review the current state of the art regarding the role of the clinical laboratory in diagnostic testing for the factor V Leiden (FVL) thrombophilic mutation (and other protein C resistance disorders), and to generate, through literature reviews and opinions of recognized thought-leaders, expert consensus recommendations on methodology and diagnostic, prognostic, and management issues pertaining to clinical FVL testing.

DATA SOURCES, EXTRACTION, AND SYNTHESIS

An initial thorough review of the medical literature and of current best clinical practices by a panel of 4 experts followed by a consensus conference review, editing, and ultimate approval by the majority of a panel of 28 additional coagulation laboratory experts.

CONCLUSIONS

Consensus recommendations were generated for topics of direct clinical relevance, including (1) defining those patients (and family members) who should (and should not) be tested for FVL; (2) defining the preferred FVL laboratory testing methods; and (3) defining the therapeutic, prophylactic, and management ramifications of FVL testing in affected individuals and their family members. As FVL is currently the most common recognized familial thrombophilia, it is hoped that these recommendations will assist laboratorians and clinicians caring for patients (and families) with this common mutation.

Laboratory evaluation of hypercoagulability with venous or arterial thrombosis

OBJECTIVE

To provide recommendations for hypercoagulation testing for patients with venous, arterial, or neurovascular thrombosis, as reflected in the medical literature and the consensus opinion of recognized experts in the field.

DATA SOURCES, EXTRACTION, AND SYNTHESIS

The authors extensively examined the literature and current practices, and prepared a draft manuscript with preliminary recommendations. The draft manuscript was circulated to each of the expert participants (n = 30) in the consensus conference prior to the convening of the conference. The manuscript and recommendations were then presented at the conference for discussion. Recommendations were accepted if a consensus of the 28 experts attending the conference was reached. The discussions were also used to revise the manuscript into its final form.

CONCLUSIONS

The resulting article provides 17 recommendations for hypercoagulation testing in the setting of venous, arterial, or neurovascular thrombosis. The supporting evidence for test selection is analyzed and cited, and consensus recommendations for test selection are presented. Issues for which a consensus was not reached at the conference are also discussed.

Termination of pregnancy following panic-stopping of oral contraceptives

This study assessed characteristics of women presenting for termination of pregnancy subsequent to stopping combined oral contraceptive use in response to publicity-mediated fears regarding venous thromboembolism. Records of 400 women attending for pregnancy termination assessment were reviewed retrospectively. Panic-stopping of oral contraceptives was implicated in 9.5%. Nearly 50% of combined pill users claimed their pregnancy resulted from panic-stopping because of media-promoted fear of health risks, especially 'clots.' Panic-stoppers had significantly lower identified risk factors for venous thromboembolism than pill users who had not panic-stopped. The relative safety of third-generation pills is under debate. The risk-benefit ratio of contraceptive pills is overwhelmingly positive but practitioners must be vigilant in screening for risk factors and contraindications. Panic-stopping results in unwanted pregnancies with concomitant psychological distress and potential physical morbidity. In future situations where research findings may precipitate drug scares, we recommend recall of patients by their health provider, funded by the relevant health authority or pharmaceutical companies, to allow discussion of risks before the media is enabled to have access to the information.

Pathogenesis of venous thromboembolism

Three factors are related with the pathogenesis of venous thrombosis: (1) blood stasis, (2) hypercoagulability, and (3) vessel damage. Local and systemic factors are implicated in blood stasis. Remarkable advances have been recently achieved regarding the understanding of the concept of hypercoagulability, with special emphasis to thrombophilic molecular abnormalities. Increased thromboembolic risk has been described in patients with antithrombin III, protein C, or protein S deficiencies as well as factor V Leiden, prothrombin mutation G20210A, or hyperhomocystinemia. Vessel wall has a remarkable role in protecting against and in promoting thrombosis. The role of inflammation on venous thrombosis is under investigation.

Thrombophilia: what's a practitioner to do?

Management of thrombophilia is an ever-changing field as new disorders are described and additional clinical experience accrues. This paper addresses three common management issues in the care of patients with thrombophilia. The first two topics are updates for common but perplexing hypercoagulable states and the last topic introduces a new option for optimal management of oral anticoagulant therapy. Dr. Jacob Rand updates and organizes the approach to patients with antiphospholipid syndrome. This syndrome is a common acquired thrombophilic state, but the diagnosis and treatment of patients remains a challenge. Dr. Rand outlines his diagnostic and treatment strategies based on the current understanding of this complicated syndrome. Dr. Barbara Konkle addresses the special concerns of managing women with thrombophilia. Hematologists are often asked to advise on the risks of hormonal therapy or pregnancy in a woman with a personal or family history of thrombosis or with an abnormal laboratory finding. Dr. Konkle reviews the available data on the risks of hormonal therapy and pregnancy in women with and without known underlying thrombophilic risk factors. In Section III, Dr. Gail Macik will discuss a new approach to warfarin management. Several instruments are now available for home prothrombin time (PT) monitoring. Self-testing and self management of warfarin are slowly emerging as reliable alternatives to traditional provider-based care and Dr. Macik reviews the instruments available and the results of studies that support this new management option.

Effect of second- and third-generation oral contraceptives on fibrinolysis in the absence or presence of the factor V Leiden mutation

Third-generation oral contraceptives (OC) have been associated with an increased risk of venous thrombosis compared with second-generation OC. To find an explanation for this increased risk, the effect of a second- and third-generation OC and of the progestagens used in these pills on several fibrinolytic parameters was studied in the absence or presence of the factor V Leiden mutation. In a single-center, double-blind trial, 51 women without and 35 women with the factor V Leiden mutation were randomized to either a second-generation (30 microg ethinylestradiol/150 microg levonorgestrel) or a third-generation (30 microg ethinylestradiol/150 microg desogestrel) oral contraceptive. After two menstrual cycles of use and a wash-out period of two cycles, the participants received the corresponding progestagen-only preparation containing 150 microg levonorgestrel or 150 microg desogestrel. D-Dimers, thrombin-activatable fibrinolysis inhibitor (TAFI) and the clot lysis time in the absence (LYSmin) or the presence (LYSplus) of a blocking anti-factor XI antibody were determined in plasmas of the participating women, and the mean difference in changes between the OC were calculated. Both combined OC induced increased plasma levels of D-dimers and TAFI, and induced a prolongation of LYSplus, whereas LYSmin hardly changed. Virtually no changes in fibrinolytic parameters were observed for the progestagen-only preparations. No differential effects between levonorgestrel- and desogestrel-containing OC were found in women without factor V Leiden. Women with the mutation on levonorgestrel-containing OC showed an increased LYSplus compared with desogestrel containing OC (3.9; 95% confidence interval, 0.1-7.7). When using progestagen-only preparations, no differential effect on the fibrinolytic parameters were found, except for non-carriers on levonorgestrel who showed a reduced LYSmin compared with non-carriers on desogestrel (-4.0; 95% confidence interval, -7.8 to -0.2). In conclusion, the effect of oral contraceptives on fibrinolytic parameters is largely independent of the type of progestagen. The increased fibrinolytic activity during OC use appears to be induced by the estrogen component and may be counteracted by increased TAFI activation. This may result in an enhanced downregulation of fibrinolysis.

Factor V Leiden, hormone replacement therapy, and risk of venous thromboembolic events in women with coronary disease

Oral contraceptive use in women with factor V Leiden is associated with increased rates of venous thromboembolic events (VTEs). However, the effects of hormone replacement therapy (HRT) in postmenopausal women with factor V Leiden are not known. A nested case-control study was conducted among women with established coronary disease enrolled in 2 randomized clinical trials of HRT, the Heart and Estrogen/Progestin Replacement Study (HERS) and the Estrogen Replacement and Atherosclerosis (ERA) trial. The Leiden mutation was present in 8 (16.7%) of 48 cases with VTE compared with only 7 (6.3%) of 112 controls (odds ratio [OR](Leiden) 3.3, 95% CI 1.1 to 9.8; P=0.03). In women without the factor V Leiden mutation, risk associated with HRT use was significantly increased (OR(HRT) 3.7, 95% CI 1.4 to 9.4; P<0.01). On the other hand, in women with the factor V Leiden mutation, the estimated risk associated with HRT was increased nearly 6-fold, although the CIs were wide and included unity (OR(HRT) 5.7, 95% CI 0.6 to 53.9; P=0.13). The OR for women with the Leiden mutation who were also assigned to HRT compared with wild-type women assigned to placebo was 14.1 (95% CI 2.7 to 72.4, P=0.0015). In women with the factor V Leiden mutation who were treated with HRT, the estimated absolute incidence of VTE was 15.4 of 1000 per year compared with 2.0 of 1000 per year in women without the mutation who were taking a placebo (P=0.0015). On the basis of these data, in women with coronary disease, the estimated number needed to screen for factor V Leiden to avoid an HRT-associated VTE during 5 years of treatment is 376. If factor V Leiden genotyping becomes less expensive, it could be cost effective to screen for the presence of the mutation before instituting HRT in women with coronary disease.

Factor V Leiden mutation screened by PCR and detected with lanthanide-labeled probes

The Factor V Leiden mutation is an important human polymorphism, responsible for increased risk of venous thrombosis in heterozygotes as well as homozygotes. Therefore, screening is a useful possibility, and many detection systems have been described for PCR products. We have developed a simplified and robust assay using oligonucleotide probes for normal and mutant sequences, labeled with europium and samarium, respectively, and measured by time-resolved fluorescence. Populations consisting of 233 Welsh and 148 Irish subjects were examined by both restriction fragment length polymorphism (RFLP) analysis and our assay. The allele frequency was 14/466 in the Welsh and 5/296 in the Irish population, in line with other surveys of European populations. Results were not obtained in 2/381 samples by RFLP, compared with 1/381 with our method. We conclude that our method represents an improved system capable of considerable throughput at reasonable cost.

Risk of Arterial Thrombosis in Relation to Oral Contraceptives (RATIO) study: oral contraceptives and the risk of ischemic stroke

BACKGROUND AND PURPOSE

Epidemiological studies have shown an increased risk of venous thrombosis in women taking third-generation oral contraceptives, ie, those containing the progestogens desogestrel or gestodene. This study assesses the risk of ischemic stroke with several types of oral contraceptives.

METHODS

A multicenter, population-based, case-control study was performed in 9 Dutch centers in women aged 18 to 49 years. Women with a first ischemic stroke were compared with control women without vascular diseases. The control subjects were recruited by random-digit dialing and were stratified by age, area of residence, and year of stroke. All patients and control subjects filled in a questionnaire about the use of oral contraceptives and risk factors for ischemic stroke. Odds ratios were adjusted for the stratification factors.

RESULTS

Two hundred three women with an ischemic stroke and 925 control women were included. The risk of stroke in women using any type of oral contraceptives versus none was 2.3 (95% CI 1.6 to 3.3). Current users of first-generation oral contraceptives had an odds ratio of 1.7 (95% CI 0.7 to 4.4). Low-dose second-generation oral contraceptives increased the risk of stroke 2.4 times (95% CI 1.6 to 3.7), and third-generation oral contraceptives increased the risk of stroke 2.0 times (95% CI 1.2 to 3.5). The risk of stroke in women using third-generation oral contraceptives was not different from that in women using second-generation oral contraceptives (odds ratio 1.0, 95% CI 0.6 to 1.8).

CONCLUSIONS

Third-generation oral contraceptives (containing desogestrel or gestodene) confer the same risk of first ischemic stroke as second-generation oral contraceptives (containing levonorgestrel).

Individual risk assessment of thrombosis in pregnancy

BACKGROUND

Thromboembolic complications during pregnancy are major contributors to maternal death, but there is no reliable way to estimate the absolute risk of thrombosis before the occurrence of a thromboembolic complication.

OBJECTIVE

To create a model for individual estimation of thrombosis risk during pregnancy and to determine the distribution of risk estimates in a series of gravidae.

METHOD AND PATIENTS

Estimates of absolute risk of pregnancy-related thromboembolism were calculated by multiplying reported figures of thrombosis incidence by prevalence-adjusted odds ratios of the following variables: smoking, parity, preeclampsia, mode of delivery, age, overweight, activated protein C resistance (FV Leiden or FV:Q506), thrombosis heredity, and previous thrombosis. We present the risk distribution among a unselected prospectively gathered cohort of 2384 unselected gravidae who were interviewed and tested for activated protein C resistance in early pregnancy.

RESULTS AND CONCLUSIONS

A model for individual estimation of the absolute risk of thrombosis is presented, which is provided to the readers as a free automatic Internet-based service (http://www.riskpreg.com). As compared with antepartum, more women at high risk can be identified in the postpartum period and we suggest that this might be of use in planning the prevention of thrombosis.

Activated protein C resistance, the factor V Leiden mutation, and a laboratory testing algorithm

OBJECTIVES

To present the current understanding of factor V Leiden and activated protein C resistance, and to propose a laboratory testing algorithm.

DATA SOURCES

Publications on MEDLINE with the terms factor V Leiden or activated protein C resistance through mid 2001, as well as publications in the authors' files, were screened for inclusion in this report.

STUDY SELECTION

Original studies that report a novel finding on testing or clinical features of activated protein C resistance or factor V Leiden are included. Data Extraction.-The novel or key findings from the selected studies are analyzed.

DATA SYNTHESIS

Protein C and protein S are the integral components of an anticoagulation pathway that limits fibrinogen conversion to fibrin through the degradation of factors Va and VIIIa. When factor Va is resistant to degradation by activated protein C, this anticoagulation pathway does not operate properly, and patients have an increased risk for thrombosis. This report describes the protein C/protein S pathway, the significance of activated protein C resistance and the factor V Leiden mutation, and the clinical testing used to detect activated protein C resistance and the factor V Leiden mutation. A proposed laboratory testing algorithm is also provided.

CONCLUSIONS

Factor V Leiden is a risk factor for venous thrombosis and it is particularly common in white populations. A laboratory testing algorithm is proposed.

Oral contraceptives and venous thromboembolism: a five-year national case-control study

The objective of this study was to assess the influence of oral contraceptives (OCs) on the risk of venous thromboembolism (VTE) in young women. A 5-year case-control study including all Danish hospitals was conducted. All women 15-44 years old, suffering a first ever deep venous thrombosis or a first pulmonary embolism (PE) during the period January 1, 1994, to December 30, 1998, were included. Controls were selected annually, 600 per year in 1994-1995 and 1200 per year 1996-1998. Response rates for cases and controls were 87.2% and 89.7%, respectively. After exclusion of nonvalid diagnoses, pregnant women, and women with previous thrombotic disease, 987 cases and 4054 controls were available for analysis. A multivariate, matched analysis was performed. Controls were matched to cases within 1-year age bands. Adjustment was made for confounding influence (if any) from the following variables: age, year, body mass index, length of OC use, family history of VTE, cerebral thrombosis or myocardial infarction, coagulopathies, diabetes, years of schooling, and previous birth. The risk of VTE among current users of OCs was primarily influenced by duration of use, with significantly decreasing odds ratios (OR) over time: <1 year, 7.0 (5.1-9.6); 1-5 years, 3.6 (2.7-4.8); and >5 years, 3.1 (2.5-3.8), all compared with nonusers of OCs. After adjustment for confounders, current use of OCs with second- (levonorgestrel or norgestimate) and third- (desogestrel or gestodene) generation progestins when compared with nonuse resulted in ORs for VTE of 2.9 (2.2-3.8) and 4.0 (3.2-4.9), respectively. After adjusting for progestin types and length of use, the risk decreased significantly with decreasing estrogen dose. With 30-40 microg as reference, 20 and 50 microg products implied ORs of 0.6 (0.4-0.9) and 1.6 (0.9-2.8), respectively (p(trend) = 0.02). After correction for duration of use and differences in estrogen dose, the third/second-generation risk ratio was 1.3 (1.0-1.8; p <0.05). In conclusion, use of OCs was associated significantly to the risk of VTE. The risk among current users was reduced by more than 50% during the first years of use. The risk increased more than 100% with increasing estrogen dose, and the difference in risk between users of third- and second-generation OCs, after correction for length of use and estrogen dose, was 33%.

Interaction of hemostatic genetics with hormone therapy: new insights to explain arterial thrombosis in postmenopausal women

Genetic variants of key hemostatic mediators increasingly have been proposed as risk factors for atherothrombosis. The Hormone and Estrogen/Progestin Replacement Study group recently reported that the initiation of estrogen replacement in postmenopausal women with known coronary heart disease is associated with an early increase in cardiovascular events. A putative genetic susceptibility factor has been proposed a potential mediator of this increased event risk. This review outlines the recent literature to support the premise for this important proposal. Genetic profiling has great potential to improve the safety and efficacy of individualized pharmacotherapy in postmenopausal women and other at-risk populations for the prevention of cardiovascular disease.

Female hormones and thrombosis

Exogenous hormones are used by more than a hundred million women worldwide as oral contraceptives or for postmenopausal hormone replacement. Oral contraceptives increase the risk of venous thrombosis, of myocardial infarction, and of stroke. The risk is highest during the first year of use. The venous thrombotic risk of oral contraceptives is high among women with coagulation abnormalities and with so-called third-generation contraceptives (containing desogestrel or gestodene). The risk of myocardial infarction does not appear to depend on coagulation abnormalities or the type of oral contraceptive. Hormone replacement therapy increases the risk of venous thrombosis. This risk is also highest in the first year of use and among women with coagulation abnormalities. The risk becomes very high in women with a previous venous thrombosis. Randomized trials have not confirmed a beneficial effect of postmenopausal hormones on the occurrence of myocardial infarction.

Hypercoagulability: too many tests, too much conflicting data

It is now possible to identify hereditary and acquired risk factors in a substantial percentage of patients presenting with a venous thrombotic event. The clinician is faced with an ever-growing number of laboratory tests that can be ordered in such patients, and there is considerable uncertainty as to how this information should be utilized in patient management. Some have argued that widespread testing of thrombosis patients for prothrombotic abnormalities such as the factor V Leiden and prothrombin G20210A mutations has been prematurely adopted into clinical practice as there are few data that their identification leads to improved clinical outcomes. Dr. Rosendaal provides an overview of the epidemiology of venous thrombosis with an emphasis on hereditary and acquired risk factors. The presentation will include information obtained from properly designed case-control studies as well as family studies. While some have suggested treatment strategies for managing patients with hereditary thrombophilia with prior thrombotic events or for managing patients undergoing procedures associated with increased thrombotic risk, clinical decision making is complicated by the need to assess the risk of recurrence and the likely benefit of prolonged anticoagulation versus the associated bleeding risk. Drs. Bauer, Heit, and Rosendaal discuss their approaches to patient management. Case presentations are used to illustrate the impact of laboratory test results on decisions.

Venous Thromboembolism and Oral Contraceptives

Recent studies of currently available oral contraceptives indicate that the risk of major sequelae is low in young women (aged between 20 and 24 years). Venous thromboembolism remains one event that can occur in users independent of the presence of risk factors. However, the attributable risk is small, with a range of approximately 7 to 18 events per 100 000 women annually. This risk is directly proportional to estrogen dosage starting at levels of 30-35 microg. The type of progestogen (progestin) may also influence risk, though recent studies are controversial. In particular, there is debate surrounding whether desogestrel and gestodene carry a greater risk of thromboembolism than levonorgestrel. Modifiable risk factors for venous thromboembolism include hemostatic disorders, especially factor V Leiden, and possibly obesity. Cigarette smoking is not a significant risk factor in oral contraceptive users. With the exception of avoiding oral contraceptive use among women with a either a personal history of venous thromboembolism or a strong family history (until evaluated for hemostatic abnormalities), and perhaps limiting the use of desogestrel- or gestodene-containing oral contraceptives, there is little clinicians can do to reduce the risk of this disorder.

Oral contraceptives and the risk of myocardial infarction

BACKGROUND

An association between the use of oral contraceptives and the risk of myocardial infarction has been found in some, but not all, studies. We investigated this association, according to the type of progestagen included in third-generation (i.e., desogestrel or gestodene) and second-generation (i.e., levonorgestrel) oral contraceptives, the dose of estrogen, and the presence or absence of prothrombotic mutations

METHODS

In a nationwide, population-based, case-control study, we identified and enrolled 248 women 18 through 49 years of age who had had a first myocardial infarction between 1990 and 1995 and 925 control women who had not had a myocardial infarction and who were matched for age, calendar year of the index event, and area of residence. Subjects supplied information on oral-contraceptive use and major cardiovascular risk factors. An analysis for factor V Leiden and the G20210A mutation in the prothrombin gene was conducted in 217 patients and 763 controls

RESULTS

The odds ratio for myocardial infarction among women who used any type of combined oral contraceptive, as compared with nonusers, was 2.0 (95 percent confidence interval, 1.5 to 2.8). The adjusted odds ratio was 2.5 (95 percent confidence interval, 1.5 to 4.1) among women who used second-generation oral contraceptives and 1.3 (95 percent confidence interval, 0.7 to 2.5) among those who used third-generation oral contraceptives. Among women who used oral contraceptives, the odds ratio was 2.1 (95 percent confidence interval, 1.5 to 3.0) for those without a prothrombotic mutation and 1.9 (95 percent confidence interval, 0.6 to 5.5) for those with a mutation

CONCLUSIONS

The risk of myocardial infarction was increased among women who used second-generation oral contraceptives. The results with respect to the use of third-generation oral contraceptives were inconclusive but suggested that the risk was lower than the risk associated with second-generation oral contraceptives. The risk of myocardial infarction was similar among women who used oral contraceptives whether or not they had a prothrombotic mutation.

Evaluating the safety of medicines, with particular reference to contraception

Toxicological studies and clinical trials cannot be expected to predict all important adverse effects of medicines and contraceptives. Post-marketing surveillance is essentially an epidemiological task that involves detecting associations between drugs and events. The first alerts about drug safety problems have often come from case reports, but epidemiological studies are needed to confirm adverse (or beneficial) effects and to provide quantitative information. This article illustrates methodological principles by considering three examples from the field of contraceptive safety: oral contraceptives and breast cancer, intrauterine contraception and pelvic inflammatory disease, and newer oral contraceptives and venous thromboembolism. Key issues that emerge include bias and confounding, the place of subgroup analyses, random error, and the use of computerized databases. In research on contraceptive and drug safety, conclusions usually need to be based on careful assessment of multiple observational studies.

Third-generation progestogen type influences hemostatic changes caused by oral contraceptives in Brazilian women

We compared the effects of two third-generation progestogens, desogestrel (DSG) and gestodene (GSD), on coagulation and fibrinolysis in Brazilian users of oral contraceptives (OCs). Forty-six women were evaluated before treatment and after six cycles of treatment. The coagulation, anticoagulant, and fibrinolytic systems were investigated. During the use of the DSG-containing OC, the activity of factors VII, VIII, IX, X, and XII increased significantly whereas the GSD-containing OC caused no changes in coagulation parameters. Concerning the anticoagulant pathways, the DSG-containing OC increased protein C levels and decreased total protein S levels, and the GSD-containing OC only decreased total protein S. Both OCs increased plasminogen activity, although the DSG-containing OC increased fibrin degradation products levels and decreased the tissue plasminogen activator antigen. In conclusion, we have found that in Brazilian women the effects of DSG and GSD on hemostatic parameters are different and, therefore, third-generation progestogens may not contribute equally to the thrombotic risk.

Current status of fertility control methods in India

Approximately 48.2% of couples of 15 to 49 years of age practice family planning methods in India. Female sterilization accounts for 34.2%, with male sterilization declining from 3.4% in 1992-93 to 1.9% in 1998-99. Use of the condom increased to 3.1% from 2.4%. There is an urgent need for research to develop new contraceptive modalities especially for men and also for women and to make existing methods more safe, affordable and acceptable. Current efforts in India to develop a male contraceptive are mainly directed towards (i) development of antispermatogenic agents to suppress sperm production, (ii) prevention of sperm maturation, (iii) prevention of sperm transport through vas deferens or rendering these sperm infertile and (iv) prevention of sperm deposition. Research work in the field of prevention of sperm transport through vas deferens has made significant advances. Styrene maleic anhydride (SMA) disturbed the electrical charge of spermatozoa leading to acrosome rupture and consequent loss in fertilizing ability of sperm. A multicentre phase-III clinical trial using SMA is continuing and it is hoped that the SMA approach would be available in the near future as an indigenously developed injectable intra-vasal male contraceptive. The safety and efficacy of available oral contraceptives were evaluated. An indigenously developed oral contraceptive 'Centchorman', which is a nonsteroidal, weakly estrogenic but potently antiestrogenic, was found to be safe and effective and is now being marketed in India since 1991 as a 'once a week' pill. Cyclofem and Mesigyna have been recommended as injectable contraceptives with proper counselling and service delivery by Indian studies. It has been recommended that these injectable contraceptives be added to the existing range of contraceptive methods available in the National Family Planning Programme. Based on the Indian studies CuT 200 was also recommended. Studies have indicated the advantage of intrauterine devices (IUD); they are long acting, relatively easily removed and fertility returns rapidly after their removal. Recent studies have recommended CuT 200 for use up to 5 years. The combination of some plant products i.e. Embelia ribes, Borax and Piper longum has been found to be safe and effective as a female contraceptive and the results of phase-I clinical trials are encouraging. Research work is going on in the country in various areas with special reference to hormonal contraceptive - a three monthly injectable contraceptive, immuno-contraceptives, antiprogestins, etc.

Effect of second and third generation oral contraceptives on lipid metabolism in the absence or presence of the factor V Leiden mutation

OBJECTIVES

The effect of a second and third generation oral contraceptive and of the progestagens used in these pills on lipid metabolism was studied in the absence or presence of the factor V Leiden mutation.

DESIGN

A single centre, double blind randomized trial.

SETTING

University Medical Centre.

SUBJECTS

A total of 51 women without and 35 women with the factor V Leiden mutation.

INTERVENTIONS

A second generation (30 microg ethinylestradiol/150 microg levonorgestrel) or a third generation (30 microg ethinylestradiol/l 50 microg desogestrel) oral contraceptive. After two cycles of use and a wash-out period of two cycles, the participants received the corresponding progestagen-only preparation containing 150 microg levonorgestrel or 150 microg desogestrel.

MAIN OUTCOME MEASURES

Mean difference in changes between the treatment groups on total cholesterol, HDL, LDL, triglycerides and total/HDL cholesterol ratio.

RESULTS

Compared with levonorgestrel, desogestrel-containing oral contraceptives caused in women without the factor V Leiden mutation significant changes in HDL (0.43; 95% confidence interval [CI] 0.25-0.61), LDL (-0.55; 95% CI -0.90 to -0.20), triglycerides (0.19; 95% CI 0.06-0.32) and total/ HDL cholesterol ratio (-0.87; 95% CI -1.21 to -0.53). When the progestagen-only preparations were used, differential changes were found for HDL (0.16; 95% CI 0.03-0.29), LDL (-0.31; 95% CI - 0.56 to -0.05) and total/HDL cholesterol ratio (-0.55; 95% CI -0.84 to -0.26). Desogestrel-only caused changes opposite to those of desogestrel-containing oral contraceptives. For cholesterol and triglycerides, this effect was also found for levonorgestrel-only in comparison with levonorgestrel-combined oral contraceptives. Levonorgestrel appeared to induce the effect on HDL. Almost all results were similar for women with the factor V Leiden mutation.

CONCLUSION

It appears that desogestrel counteracts the effects of oestrogens to a lesser extent than levonorgestrel. Desogestrel-containing oral contraceptives have therefore a more favourable influence on cholesterol metabolism in comparison with levonorgestrel-containing oral contraceptives.

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.

Exogenous estrogen in systemic lupus erythematosus: oral contraceptives and hormone replacement therapy

The role of exogenous estrogen in the initiation and maintenance of human SLE remains very controversial. Although cohort studies suggest an increase in the incidence of SLE with both oral contraceptives and hormone replacement therapy, recent retrospective studies suggest that the risk of flare is not increased with hormone replacement therapy. However, exogenous estrogen does increase hypercoagulability, an issue in SLE patients with antiphospholipid antibodies. The prospective SELENA study will ultimately address whether exogenous estrogen increases severe flares in SLE.

Factor V Leiden: a clinical review

Factor V Leiden is the most prevalent genetic thrombophilia in people of European descent. Since its discovery, much clinical information has been gathered regarding the distribution and prevalence of the genetic mutation, the mechanism of thrombophilia, and its association with clinical thromboembolic events. Although its association with venous thromboembolism is clear, the role of Factor V Leiden in other disease states is not clear. A review of the literature regarding the mechanism of hypercoagulability, genetic versus functional diagnostic tests, screening issues, relationship to arterial thromboses, pregnancy and pregnancy complications, and treatment are discussed.

Management of thrombosis in antiphospholipid antibody syndrome

Antiphospholipid antibody positive patients are at risk for venous and arterial thrombosis. The risk of recurrent thromboembolism is high. Although the standard of care is high-intensity warfarin after a thromboembolic event, some studies indicate that this degree of anticoagulation is not needed. There is an urgent need of clinical trials to address management of thrombosis in antiphospholipid syndrome.

Risk of venous thromboembolism from oral contraceptives containing gestodene and desogestrel versus levonorgestrel: a meta-analysis and formal sensitivity analysis

Controversy exists regarding whether oral contraceptives (OCs) containing desogestrel and gestodene are associated with an increased risk of venous thromboembolism (VTE) versus OCs containing levonorgestrel. We were interested in synthesizing the available data, exploring explanations for mixed results, and characterizing the degree of uncontrolled confounding that could have produced a spurious association. We performed a meta-analysis and formal sensitivity analysis of studies that examined the relative risk of VTE for desogestrel and gestodene versus levonorgestrel. Twelve studies, all observational, were included. The summary relative risk (95% CI) was 1.7 (1.3-2.1; heterogeneity p = 0.09). If real, the incremental risk of VTE would be about 11 per 100,000 women per year. An association was present when accounting for duration of use and when restricted to the first year of use in new users. However, in the sensitivity analysis, the association abated in many, but not all, scenarios in which an unmeasured confounding factor increased the risk of VTE three to fivefold and in nearly all examined scenarios in which the factor increased the risk 10-fold. The summary relative risk of 1.7 does not appear to be caused by depletion of susceptibles, but is sensitive to a modest degree of unmeasured confounding. Whether such confounding occurred is unknown. However, given this sensitivity, this issue probably cannot be settled unequivocally with observational data. In the absence of a definitive answer, this apparent increased risk, together with its uncertainty and small magnitude and its important consequences, should be considered when selecting an OC for a given woman.

Third generation oral contraceptives and risk of venous thrombosis: meta-analysis

OBJECTIVE

To evaluate quantitatively articles that compared effects of second and third generation oral contraceptives on risk of venous thrombosis.

DESIGN

Meta-analysis.

STUDIES

Cohort and case-control studies assessing risk of venous thromboembolism among women using oral contraceptives before October 1995.

MAIN OUTCOME MEASURES

Pooled adjusted odds ratios calculated by a general variance based random effects method. When possible, two by two tables were extracted and combined by the Mantel-Haenszel method.

RESULTS

The overall adjusted odds ratio for third versus second generation oral contraceptives was 1.7 (95% confidence interval 1.4 to 2.0; seven studies). Similar risks were found when oral contraceptives containing desogestrel or gestodene were compared with those containing levonorgestrel. Among first time users, the odds ratio for third versus second generation preparations was 3.1 (2.0 to 4.6; four studies). The odds ratio was 2.5 (1.6 to 4.1; five studies) for short term users compared with 2.0 (1.4 to 2.7; five studies) for longer term users. The odds ratio was 1.3 (1.0 to 1.7) in studies funded by the pharmaceutical industry and 2.3 (1.7 to 3.2) in other studies. Differences in age and certainty of diagnosis of venous thrombosis did not affect the results.

CONCLUSIONS

This meta-analysis supports the view that third generation oral contraceptives are associated with an increased risk of venous thrombosis compared with second generation oral contraceptives. The increase cannot be explained by several potential biases.

Use of exogenous estrogens in systemic lupus erythematosus

OBJECTIVE

To review the current literature on the safety of using exogenous estrogens in patients with systemic lupus erythematosus (SLE).

METHOD

A MEDLINE search for articles published between 1970 and 2000 regarding the relationship between estrogens and SLE was performed. Emphasis was put on human studies, treatment trials, and epidemiologic surveys.

RESULTS

The use of exogenous estrogens in healthy women increases the risk of SLE development. For patients with established SLE, a hypoestrogenemic state appears to be protective against severe flares, whereas exogenous estrogen administration or hyperestrogenemia induced by hormonal manipulation may exacerbate the disease in certain individuals. Both the use of oral contraceptives and the use of hormonal replacement therapy (HRT) increase the chance of venous thromboembolism. The presence of antiphospholipid antibodies may aggravate the risk of thrombosis in SLE. In retrospective studies, HRT appears to be well tolerated in postmenopausal SLE patients.

CONCLUSIONS

There are no prospective data that show a deleterious effect of exogenous estrogens on disease activity in human SLE. Oral contraceptives may be considered for patients with SLE in the absence of active nephritis or antiphospholipid antibodies. The slight increase in venous thromboembolic risk should not be the chief deterrent to the use of HRT in postmenopausal SLE patients, considering its various health benefits.

Putting risk in perspective: an evidence-based approach to selected risks associated with the use of oral contraception

Although use of oral contraceptives is an effective way to prevent unintended pregnancy, concerns exist about associated adverse health outcomes. The concept of risk and different approaches to describing risk are discussed, and studies of health risks associated with specific exposures are used to illustrate the differences between relative and absolute risk. Evidence about health risks associated with use of oral contraceptives is presented within the context of population-based risk estimates.

Oral contraceptives, thrombosis and haemostasis

The use of oral contraceptives is a well-established acquired risk factor for venous thrombosis. In 1995, a number of epidemiological studies were published which suggested that women who use third generation oral contraceptives that contain desogestrel or gestodene as progestagen are exposed to a two- to threefold higher risk for venous thrombosis than women using second generation oral contraceptives which contain levonorgestrel. In this paper, the effects of oral contraceptives on the haemostatic system are discussed. It appears that plasma from oral contraceptive users is resistant to the anticoagulant action of activated protein C (APC). This phenomenon, called acquired APC resistance, is more pronounced in users of desogestrel or gestodene-containing oral contraceptives than in women who use oral contraceptive pills with levonorgestrel. On the basis of these observations, it was proposed that acquired APC resistance may be the mechanistic basis of the increased risk for venous thrombosis during oral contraceptive use and for the further increased thrombotic risk of third generation oral contraceptive users. Furthermore, the results of a recent cross-over study are discussed. This study indicated that a large number of other haemostatic parameters were changed during oral contraceptive use. Some of these changes were more pronounced on desogestrel-containing oral contraceptives. The cross-over study also showed that the increased fibrinolytic activity during OC use is counterbalanced by an enhanced activity of thrombin-activatable fibrinolysis inhibitor (TAFI), a protein that participates in the inhibition of fibrinolysis.

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.

Contraception in the adolescent: an update

Contraception remains an important part of national efforts to reduce adolescent pregnancy in the United States. A number of safe and effective contraceptive methods are available for our youth, including abstinence, barrier methods, oral contraceptives, Depo-Provera, and Norplant. Research over the past few decades has resulted in a variety of oral contraceptives with reduced amounts of hormones and reduced side-effects. A number of methods have received approval by the Food and Drug Administration since the last review in 1980, including emergency contraceptives, depomedroxyprogesterone acetate, and the cervical cap. The use of condoms and vaginal spermicides continues to be recommended for all sexually active adolescents to reduce (not eliminate) the risk for acquiring sexually transmitted diseases. A polyurethane condom is now available, in addition to the latex condom and other barrier contraceptives, including the following: diaphragm, cervical cap, vaginal sponge, female condom and vaginal spermicides. Because of continuing concerns about pelvic inflammatory disease related to intrauterine devices, currently available intrauterine devices are not recommended for most adolescents. Abortion is not considered as a contraceptive method.

The relationship between use of oral contraceptives and myocardial infarction in young women with fatal outcome, compared to those who survive: results from the MICA case-control study

To examine the relationship between use of oral contraceptives and the risk of dying from myocardial infarction, we made a comparison of deceased patients and live patients (women aged less than 45) identified for the Myocardial Infarction Causality case-control study, using data obtained from general practice medical notes. There were 422 live patients and 110 deceased patients of women with a myocardial infarction with data available. The adjusted odds ratio for exposure to second generation oral contraceptives and risk of death within 28 days of a myocardial infarction compared with no oral contraceptive use was raised (2.88, 95% confidence interval 1.22-6.77), and this effect was not seen for other types of oral contraceptives including third generation oral contraceptive formulations. In absolute terms, between 47,000 and 71,000 women would have to be exposed to a second generation pill for one year to result in one extra death from myocardial infarction, and this risk applies mainly to smokers. The results suggest a slightly increased relative risk of death among those having a myocardial infarction associated with exposure to second generation oral contraceptives, but this represents a small absolute risk. Further work is required before any change in contraceptive practice should be advocated.

Thrombophilia: What's a Practitioner to Do?

Management of thrombophilia is an ever-changing field as new disorders are described and additional clinical experience accrues. This paper addresses three common management issues in the care of patients with thrombophilia. The first two topics are updates for common but perplexing hypercoagulable states and the last topic introduces a new option for optimal management of oral anticoagulant therapy. Dr. Jacob Rand updates and organizes the approach to patients with antiphospholipid syndrome. This syndrome is a common acquired thrombophilic state, but the diagnosis and treatment of patients remains a challenge. Dr. Rand outlines his diagnostic and treatment strategies based on the current understanding of this complicated syndrome. Dr. Barbara Konkle addresses the special concerns of managing women with thrombophilia. Hematologists are often asked to advise on the risks of hormonal therapy or pregnancy in a woman with a personal or family history of thrombosis or with an abnormal laboratory finding. Dr. Konkle reviews the available data on the risks of hormonal therapy and pregnancy in women with and without known underlying thrombophilic risk factors. In Section III, Dr. Gail Macik will discuss a new approach to warfarin management. Several instruments are now available for home prothrombin time (PT) monitoring. Self-testing and self management of warfarin are slowly emerging as reliable alternatives to traditional provider-based care and Dr. Macik reviews the instruments available and the results of studies that support this new management option.

Contraceptive practices in women with systemic lupus erythematosus and/or antiphospholipid syndrome: what advice should we be giving?

INTRODUCTION

Systemic lupus erythematosus (SLE) is an autoimmune oestrogen-mediated disease. Antiphospholipid syndrome (APS) is an autoimmune acquired thrombophilia. These two conditions may co-exist and are most frequently diagnosed in young women. Hormonal contraception may promote lupus activity and thromboses. Medical practitioners may not know what advice to give these women regarding contraception.

OBJECTIVES

To determine the past and present contraceptive practices of women with SLE and/or APS, and to establish the incidence of complications related to use of various contraceptives. Also, the contraceptive information given to women following diagnosis was evaluated.

STUDY DESIGN

Observational questionnaire-based study of 86 women with SLE and/or APS attending the Lupus/Thrombophilia Clinics at St. Thomas' Hospital.

RESULTS

One of the 19 (5%) women with SLE using the combined oral contraceptive pill (COCP) at the time of diagnosis reported a severe lupus 'flare'. Seven of the 32 (22%) women with APS using the COCP suffered from thromboses during use. There were no problems specific to women with SLE and/or APS using any other form of contraception. Thirty-nine (45%) women received no contraceptive information following their diagnosis, 37 (46%) were told to avoid the COCP due to the increase in lupus 'flare' and/or thromboses.

CONCLUSION

There is no clinically significant association between COCP use and lupus 'flare'. The high incidence of thromboses in women with APS using the COCP containing either second or third generation progestogens suggests that these women should be advised against using this form of contraception. Women with SLE and/or APS should be given more information about contraceptive issues.

The effects of age, body mass index, smoking and general health on the risk of venous thromboembolism in users of combined oral contraceptives

OBJECTIVES

To investigate the factors associated with idiopathic venous thromboembolism in combined oral contraceptive users and to estimate the crude and age-specific incidence rates ofidiopathic venous thromboembolism among this population.

METHODS

The UK MediPlus Database and the General Practice Research Database were searched to identify women with evidence of venous thromboembolism while exposed to combined oral contraceptives. Cohort and nested case-control studies were carried out using the same methodology on both databases. We conducted a meta-analysis using the individual data for the cases and controls from the two case-control studies to identify factors associated with idiopathic venous thromboembolism in women using combined oral contraceptives.

RESULTS

The incidence rate of idiopathic venous thromboembolism among oral contraceptive users was 39.4 per 100,000 exposed woman-years. The age-specific incidence rates were found to rise sharply after the age of 39 years. Factors identified as being significantly associated with idiopathic venous thromboembolism in women using combined oral contraceptives were: body mass index of 25 kg/m2 and over, the association rising dramatically in women with a body mass index of 35 kg/m2 or more; smoking; general ill health; and asthma.

CONCLUSION

We believe that, before prescribing combined oral contraceptives, the venous as well as the arterial factors need to be considered and, in addition, age, obesity and smoking are all relevant when assessing an individual patient's risk.

Risk of venous thromboembolism among users of third generation oral contraceptives compared with users of oral contraceptives with levonorgestrel before and after 1995: cohort and case-control analysis

OBJECTIVE

To compare the risk of idiopathic venous thromboembolism among women taking third generation oral contraceptives (with gestodene or desogestrel) with that among women taking oral contraceptives with levonorgestrel.

DESIGN

Cohort and case-control analyses derived from the General Practice Research Database.

SETTING

UK general practices, January 1993 to December 1999.

PARTICIPANTS

Women aged 15-39 taking third generation oral contraceptives or oral contraceptives with levonorgestrel.

MAIN OUTCOME MEASURES

Relative incidence (cohort study) and odds ratios (case-control study) as measures of the relative risk of venous thromboembolism.

RESULTS

The adjusted estimates of relative risk for venous thromboembolism associated with third generation oral contraceptives compared with oral contraceptives with levonorgestrel was 1.9 (95% confidence interval 1.3 to 2.8) in the cohort analysis and 2.3 (1.3 to 3.9) in the case-control study. The estimates for the two types of oral contraceptives were similar before and after the warning issued by the Committee on Safety of Medicines in October 1995. A shift away from the use of third generation oral contraceptives after the scare was more pronounced among younger women (who have a lower risk of venous thromboembolism) than among older women. Fewer cases of venous thromboembolism occurred in 1996 and later than would have been expected if the use of oral contraceptives had remained unchanged.

CONCLUSIONS

These findings are consistent with previously reported studies, which found that compared with oral contraceptives with levonorgestrel, third generation oral contraceptives are associated with around twice the risk of venous thromboembolism.

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.

Budd-Chiari syndrome: combination of genetic defects and the use of oral contraceptives leading to hypercoagulability

A young female, who had been in excellent health and had used third-generation oral contraceptives, was admitted to hospital because of abdominal pain and ascites. Budd-Chiari syndrome (BCS) was diagnosed by radiographic and histological examination. Tests for myeloproliferative disease, deficiency of coagulation inhibitors and paroxysmal nocturnal haemoglobinuria were negative. DNA investigation showed a double heterozygous defect: the Arg506Gln mutation in the factor V gene (factor V Leiden) and G20210A nucleotide substitution in the prothrombin gene. This double defect was also found in the patient's father, who had never experienced an episode of venous thromboembolism. Genetic and acquired thrombogenic risk factors are being detected increasingly in patients with BCS. With the discovery of new genetic defects leading to hypercoagulabiulity an increasing number of patients with serious thrombotic manifestations, such as BCS, will exhibit concurrence of hereditary and acquired risk factors for thrombosis.

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.

The progestin levonorgestrel induces endothelium-independent relaxation of rabbit jugular vein via inhibition of calcium entry and protein kinase C: role of cyclic AMP

The progestin and oestrogen component of oral contraceptives have been involved in the development of venous thromboembolic events in women. In the present study we determined the vasoactive effects of sex steroids used in oral contraceptives in isolated preconstricted rabbit jugular veins in the presence of diclofenac and examined the underlying mechanisms. The natural hormone progesterone, the synthetic progestins levonorgestrel, 3-keto-desogestrel, gestodene and chlormadinone acetate, and the synthetic estrogen 17 alpha-ethinyloestradiol induced concentration-dependent relaxations of endothelium-intact veins constricted with U46619. Levonorgestrel also inhibited constrictions evoked by either a high potassium (K(+)) solution or phorbol myristate acetate (PMA) in the absence and presence of extracellular calcium (Ca(2+)). In addition, levonorgestrel depressed contractions evoked by Ca(2+) and reduced (45)Ca(2+) influx in depolarized veins. Relaxations to levonorgestrel in U46619-constricted veins were neither affected by the presence of the endothelium nor by the inhibitor of soluble guanylyl cyclase, NS2028, but were significantly improved either by the selective cyclic AMP phosphodiesterase inhibitor rolipram or in the absence of diclofenac, and decreased by the protein kinase A inhibitor, Rp-8-CPT-cAMPS. Rolipram also potentiated relaxations to levonorgestrel in PMA-constricted veins in the presence, but not in the absence of extracellular Ca(2+). Levonorgestrel increased levels of cyclic AMP and inhibited PMA-induced activation of protein kinase C in veins. These findings indicate that levonorgestrel caused endothelium-independent relaxations of jugular veins via inhibition of Ca(2+) entry and of protein kinase C activation. In addition, the cyclic AMP effector pathway contributes to the levonorgestrel-induced relaxation possibly by depressing Ca(2+) entry.