Emergency contraception — mechanisms of action

Emergency contraception: Focus on the facts

Significant progress on contraception, and in particular emergency contraception, has been made in the past decade. Emergency contraception was first introduced as a stand-alone prescription in 1998, and the interaction of politics and medicine meant a tumultuous course to the drug becoming available over the counter. This article reviews how emergency contraception works, the effectiveness of different methods, pros and cons, and the history of emergency contraception.

Practice Bulletin No. 152: Emergency Contraception

Emergency contraception, also known as postcoital contraception, is therapy used to prevent pregnancy after an unprotected or inadequately protected act of sexual intercourse. Common indications for emergency contraception include contraceptive failure (eg, condom breakage or missed doses of oral contraceptives) and failure to use any form of contraception (). Although oral emergency contraception was first described in the medical literature in the 1960s, the U.S. Food and Drug Administration (FDA) approved the first dedicated product for emergency contraception in 1998. Since then, several new products have been introduced. Methods of emergency contraception include oral administration of combined estrogen-progestin, progestin only, or selective progesterone receptor modulators and insertion of a copper intrauterine device (IUD). Many women are unaware of the existence of emergency contraception, misunderstand its use and safety, or do not use it when a need arises (). The purpose of this Practice Bulletin is to review the evidence for the efficacy and safety of available methods of emergency contraception and to increase awareness of these methods among obstetrician-gynecologists and other gynecologic providers.

Reproductive health care after transplantation

Contraception, cervical cancer screening, human papillomavirus (HPV) vaccination, sexually transmitted infection (STI) screening, and menstrual disorders are issues that need to be addressed in all reproductive-aged women, including those with a history of solid organ transplantation. There are specific considerations that may alter routine care in this population. Due to teratogenic immunosuppressive medications, highly effective contraception is important to planning or appropriately timing pregnancy. Estrogen-containing methods (pill, patch, and ring) may be contraindicated. Immunosuppression is also a consideration when screening for and treating STIs including precancerous conditions of the cervix. This chapter will provide a framework to address the specific gynecologic needs of women with a history of solid organ transplantation.

The effects on ovarian activity of ulipristal acetate when 'quickstarting' a combined oral contraceptive pill: a prospective, randomized, double-blind parallel-arm, placebo-controlled study

STUDY QUESTION

What is the effect on ovarian activity of a preceding intake of ulipristal acetate (UPA) when starting a combined oral contraceptive (COC) in the mid- to late-follicular phase of the cycle?

SUMMARY ANSWER

This study shows that UPA does not affect the ability of the COC to induce ovarian quiescence.

WHAT IS KNOWN ALREADY

UPA is a progesterone receptor modulator that is available for emergency contraception (EC). In theory, UPA could alter the effectiveness of hormonal contraception started immediately following it and vice versa. Current guidelines regarding quick starting a COC following UPA are based on expert opinion only.

STUDY DESIGN, SIZE, DURATION

A double-blind, randomized, placebo-controlled trial was conducted at three separate sites, Edinburgh (Scotland), Stockholm (Sweden) and Groningen (the Netherlands), over a 5-month period in 2012. Healthy female volunteers were randomized to take either UPA or an identically packaged placebo, at mid-cycle (once a lead ovarian follicle was determined to be >13 mm on transvaginal ultrasound imaging). Participants were randomized by a computer-generated randomization schedule, allocated by sequential, sealed envelopes. All women then started 21 days of the same COC the following day. The study was designed to show non-inferiority of UPA compared with placebo in terms of the proportion of women attaining ovarian quiescence, as measured by the Hoogland scoring system, while taking COC.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 76 women were recruited over the three sites, Edinburgh (n = 18), Stockholm (n = 13), Groningen (n = 45) and received either UPA (n = 39) or placebo (n = 37).

MAIN RESULTS AND THE ROLE OF CHANCE

There were no significant differences in demographic characteristics of women in the UPA and placebo groups. Among the 76 participants treated, 47 (61.8%) reached quiescence and 25 (32.9%) ovulated. There were no significant differences between the groups in the odds ratio (OR) of reaching ovarian quiescence or not; OR 0.97 (95% CI: 0.39-2.46). All women who reached quiescence had done so after taking COCs for 14 days.

LIMITATIONS, REASONS FOR CAUTION

The main limitations of the study were that measurements of follicle size and blood tests were performed every 2-3 days and so it was not possible to determine the actual day that follicle rupture occurred for the women who ovulated. Furthermore, the ultrasonography was conducted by a number of investigators at the sites which may introduce error in the form of inter-observer variability in measurements of follicle growth. Finally, the findings of the study cannot be extrapolated to other combined hormonal methods of contraception such as the patch or ring, nor to progestogen- only methods of contraception.

WIDER IMPLICATIONS OF THE FINDINGS

This study provides evidence to suggest that UPA does not affect the ability of the COC to induce ovarian quiescence. However, this study design cannot determine whether the COC affects the ability of UPA to delay ovulation.

STUDY FUNDING/COMPETING INTERESTS

Funding was provided by HRA Pharma Paris, France. C.K., S.T.C. and K.G.D. have received funds for conducting research studies and lectures for HRA Pharma. C.K. is director of a contract research organization (Dinox). The remaining authors declare no conflicts of interests.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov: NCT01569113.

Mechanism of action of levonorgestrel emergency contraception

There has been much debate regarding levonorgestrel emergency contraception's (LNG-EC's) method of action since 1999 when the Food and Drug Administration first approved its use. Proponents of LNG-EC have argued that they have moral certitude that LNG-EC works via a non-abortifacient mechanism of action, and claim that all the major scientific and medical data consistently support this hypothesis. However, newer medical data serve to undermine the consistency of the non-abortifacient hypothesis and instead support the hypothesis that preovulatory administration of LNG-EC has significant potential to work via abortion. The implications of the newer data have important ramifications for medical personnel, patients, and both Catholic and non-Catholic emergency room protocols. In the future, technology such as the use of early pregnancy factor may have the potential to quantify how frequently preovulatory LNG-EC works via abortion. Lay Summary: How Plan B (levonorgestrel emergency contraception) works has been vigorously debated ever since the Food and Drug Administration approved it in 1999. Many doctors and researchers claim that it has either no-or at most-an extremely small chance of working via abortion. However, the latest scientific and medical evidence now demonstrates that levonorgestrel emergency contraception theoretically works via abortion quite often. The implications of the newer data have important ramifications for medical personnel, patients, and both Catholic and non-Catholic emergency room rape protocols.

[Place of persistence trouble during oral contraception and subsequent use of emergency contraception]

OBJECTIVE

In order to improve the understanding of hormonal contraceptive failures, this study evaluates the persistence of oral contraception and the use of emergency contraception (EC) during persistence incidents. We made the hypothesis of the existence of a strong link between the risk of unplanned pregnancies and these two parameters. In this study, we also evaluated women's perception of EC in order to elucidate the reasons of EC insufficient use.

METHODS

One survey was carried out on Internet on a representative sample of women, aged 16-45.

RESULTS

In this survey, 3775 French women were interviewed (source-population). We defined a target population of 2415 fertile women who had heterosexual intercourse during the last 12 months, and a population of 760 women at risk of unintended pregnancy who had unprotected sexual intercourse during the last 12 months(risk-population). A little more than 30% of the target population, meaning 20% of the source-population (n=745) stopped their contraceptive method temporarily for an average time of two months. Almost 60% of women had a risk of unwanted pregnancy during this period without contraception, which is 59% of the risk-population. Only 20% of women among the population at risk used EC. The main reasons given for EC insufficient use were the misperception of the risk of pregnancy, the lack of knowledge about EC and its way of use.

CONCLUSION

For the first time, this survey shows that 13% of women (of the source population) decide to stop temporarily their contraceptive method for an average time of two months per year. Fifty-nine percent of unplanned pregnancy situations are due to this poor contraception persistence. Although there is a need to reduce the risk of women being at risk, it seems also highly desirable to overcome the consequences of this poor persistence. Giving information about EC and a systematic prescription during contraception consultations would lead to an increased use of EC.

When states regulate emergency contraceptives like abortion, what should guide disclosure?

State laws dictating "informed consent" about surgical and chemical abortions sometimes ensnare emergency contraceptives (EC), as the science surrounding EC shows. Courts evaluating mandated disclosures gravitate to professional norms rather than the information most women would value: basic factual information about EC so that they can decide for themselves whether to use these drugs.

Worldwide research productivity in emergency contraception: a bibliometric analysis

BACKGROUND

The main goal of this study was to assess worldwide research activity in emergency contraception (EC) using bibliometric indicators.

METHODS

Data in SciVerse Scopus were searched for documents pertaining to emergency contraception. Data obtained were then exported to Microsoft Excel and analyzed using Statistical Package for Social Sciences.

RESULTS

A total of 2142 documents were published about EC worldwide. Documents were written in 27 different languages and were published from 78 countries. Publications in EC started on late 1960s. Total number of citations for published EC documents was 30154 while median citation per document was six. The h-index of the retrieved documents was 58. The leading country in EC research was United States of America with a total of 559 documents (26.10%). One hundred and ninety five (9.10%) documents were published in Contraception journal. The leading institution in EC research and publications was Princeton University (50; 2.33%) followed by University of California, San Francisco (34; 1.59%).

CONCLUSIONS

The present data revealed that there is a worldwide increasing interest in EC research. Willingness of health policy makers to make EC accessible to the public will determine the future of EC research activity and future of EC as a contraceptive method.

Emergency contraception review: evidence-based recommendations for clinicians

Several options for emergency contraception are available in the United States. This article describes each method, including efficacy, mode of action, safety, side effect profile, and availability. The most effective emergency contraceptive is the copper intrauterine device (IUD), followed by ulipristal acetate and levonorgestrel pills. Levonorgestrel is available for sale without restrictions, whereas ulipristal acetate is available with prescription only, and the copper IUD must be inserted by a clinician. Although EC pills have not been shown to reduce pregnancy or abortion rates at the population level, they are an important option for individual women seeking to prevent pregnancy after sex.

Emergency contraceptive pill safety profile. Comparison of the results of a follow-up study to those coming from spontaneous reporting

BACKGROUND

The emergency contraceptive pill (ECP) containing levonorgestrel is dispensed without a prescription in Spain since 2009. An easy access could diminish unwanted pregnancies; however, there is a risk of misuse and, in any case, of developing some adverse events. The aim of the present study is to further learn the adverse effects of this ECP.

METHODS

An ad hoc follow-up study was carried out in three community pharmacies in a city of Central Spain; the sample was composed of those women asking for the ECP; they were interviewed by telephone after at least a month since the last menses. We completed the safety profile obtained with that coming from spontaneous reporting in Spain.

RESULTS

Out of 139 women surveyed, 113 developed any adverse event--two considered as severe; the most frequently reported events were menstrual disturbances, which accounted for 21% of all events. Through spontaneous reporting, 36 cases of whatever adverse events related to levonorgestrel as ECP were identified. Twenty-five cases were considered as severe. Both types of reaction and severity were significantly different in the follow-up study and in the spontaneous reporting. Some of the reactions identified, such as miscarriage, febrile neutropenia, and porphyria, are not included in the Summary of Product Characteristics.

CONCLUSIONS

Levonorgestrel as an ECP is mostly safe. Attention should be paid to some severe events and particularly to those risk factors for them to appear. Combining spontaneous reporting with an ad hoc follow-up study, the whole safety profile of a given medication can be obtained.

Mechanisms of action of oral emergency contraception

This review gives an overview of the mechanisms of action of oral emergency contraception pills (ECPs), focusing on the levonorgestrel (LNG) and ulipristal acetate (UPA) containing ECPs. In vivo and in vitro studies have addressed the effect of EC on various possible targets. Based on these studies as well as on clinical trials it is clear that the efficacy of ECPs to prevent an unintended pregnancy depends on their mechanism of action as well as on their use in relation to the fertile window. While the main effect of both available ECPs is to prevent or delay ovulation the window of action for UPA is wider than that of LNG. This provides the biological explanation for the difference observed in clinical trials and the higher efficacy of UPA. Neither LNG nor UPA impairs endometrial receptivity or embryo implantation. Correct knowledge on the mechanism of action of ECPs is important to avoid overestimating their effectiveness and to advise women on correct use.

A randomized study on pharmacodynamic effects of vaginal rings delivering the progesterone receptor modulator ulipristal acetate: research for a novel estrogen-free, method of contraception

OBJECTIVE

To determine whether a 3-month contraceptive vaginal ring (CVR) delivering ulipristal acetate (UPA) can inhibit ovulation in 90% of cycles.

STUDY DESIGN

This was a randomized dose-finding parallel group clinical trial. Fifty-five healthy women with normal ovulation at baseline were randomized to receive a low-dose (1500 μg/day) or a high-dose (2500 μg/day) UPA-CVR for two consecutive 12-week treatment periods, followed by a recovery cycle. A subgroup of women received levonorgestrel (LNG) 1.5 mg orally twice (at the end of both 12-week ring periods) or once (at the end of the 24-week treatment). The primary outcome was ovulation suppression assessed by transvaginal ultrasound and hormone levels. Secondary outcomes included endometrial safety and bleeding patterns.

RESULTS

All subjects showed normal ovulation at baseline and recovery. Ovulation suppression was seen in 81.8% (95% CI: 73.3%, 88.5%) and 86.1% (95% CI: 78.1%, 92%) of treatment cycles with low and high-dose, respectively. Benign progesterone receptor modulator associated endometrial changes (PAEC) were seen during treatment; 78.8% at week 24, but resolved at recovery cycle. A few cases of heavy bleeding occurred near the end of the 24-week treatment, but a single dose of LNG every 12 weeks reduced the increase in endometrial thickness during the second treatment period and prevented excessive bleeding.

CONCLUSION

The 3-month UPA-CVR may become an effective long-acting, user-controlled estrogen-free contraceptive. The greatest suppression of ovulation was seen with the 2500-μg/day ring.

IMPLICATIONS

The 3-month CVR delivering UPA 2500 μg/day can become an effective user-controlled estrogen-free contraceptive method. Benign PAEC during treatment returns to normal after discontinuation. The prevention of occasional excessive withdrawal bleeding, either by a progestin or by using higher UPA levels to increase follicle suppression may permit prolonged treatment.

Preferential Cyclooxygenase 2 Inhibitors as a Nonhormonal Method of Emergency Contraception: A Look at the Evidence

OBJECTIVE

To review the literature surrounding the use of preferential cyclooxygenase 2 (COX-2) inhibitors as an alternative form of emergency contraception.

DATA SOURCES

MEDLINE (1950 to February 2014) was searched using the key words cyclooxygenase or COX-2 combined with contraception, emergency contraception, or ovulation. Results were limited to randomized control trials, controlled clinical trials, and clinical trials.

STUDY SELECTION AND DATA EXTRACTION

Human trials that measured the effects of COX inhibition on female reproductive potential were included for review.

DATA SYNTHESIS

The effects of the COX-2 inhibitors rofecoxib, celecoxib, and meloxicam were evaluated in 6 trials. Each of which was small in scope, enrolled women of variable fertility status, used different dosing regimens, included multiple end points, and had variable results.

CONCLUSIONS

Insufficient evidence exists to fully support the use of preferential COX-2 inhibitors as a form of emergency contraception. Although all trials resulted in a decrease in ovulatory cycles, outcomes varied between dosing strategies and agents used. A lack of homogeneity in these studies makes comparisons difficult. However, success of meloxicam in multiple trials warrants further study. Larger human trials are necessary before the clinical utility of this method of emergency contraception can be fully appreciated.

Physical and mental development of children after levonorgestrel emergency contraception exposure: a follow-up prospective cohort study

Levonorgestrel (LNG), a dedicated emergency contraception (EC) product, has been available over-the-counter in China for more than 14 yr. Although LNG-EC is considered to have no effects on the developing fetus if the contraceptive fails and pregnancy occurs, there have been a few studies specifically examining this issue. The purpose of this study was to compare the physical and mental development of children born after LNG-EC failure with that of a cohort of children born to mothers with no history of exposure to LNG or any teratogenic substances. A group of 195 children who were exposed to LNG-EC during their mothers' conception cycle (study group) were matched to a group of 214 children without exposure to LNG (control group). The physical and mental development of the children were evaluated and compared over a 2-yr period. There were four congenital malformations in the study group and three in the control group (2.1% vs. 1.4%, respectively, P > 0.05). Over the 2-yr follow-up period, there were no statistically significant differences between the two groups with respect to children's weight, height, head circumference, and intelligence scores, and the values of all parameters of both groups were similar to those of the national standards. In summary, LNG-EC has no effect on the physical growth, mental development, or occurrence of birth defects in children born from pregnancies in which EC failed.

Effect of changes to cost and availability of emergency contraception on users' profiles in an emergency department in Catalunya

OBJECTIVE

Emergency contraception (EC) accessibility has evolved differently in Catalunya as compared with other autonomous communities in Spain. Free-of-charge access within the Public Health System was authorised in 2004, and over-the-counter (OTC) access was implemented in 2009. The aim of the study is to assess the impact of these measures on demand and users' profiles at our institution.

METHODS

A retrospective study, in our Emergency Department, was conducted to evaluate EC requests in relationship to accessibility modifications. The age of women and which days of the week they attended were analysed.

RESULTS

The number of EC requests, the distribution by age and the demand over the week remained stable after access to EC became free of charge. However, requests sharply decreased following OTC access implementation. Distribution by age also changed, with a significant increase in requests from women under 25 years (72% vs 56%, p < 0.001). Demand was greatest on Sunday and Monday, and this distribution persisted over the study period.

CONCLUSION

EC requests remained unchanged following free-of-charge access to EC, but decreased after OTC implementation. Women currently seeking EC at no cost at our institution are more likely to be younger and to request it on a Monday.

Mifepristone: a potential clinical agent based on its anti-progesterone and anti-glucocorticoid properties

Nowadays, unwanted pregnancy is a major globe tragedy for millions of women, associated with significant direct and indirect costs, no matter for individuals or society. The progesterone receptor antagonist steroid, mifepristone has been widely and effectively using throughout the world for medical abortion, but to a lesser extent for emergency contraception. In this review, we hope to explore the role of mifepristone as a contraceptive, particularly for emergency contraception. Studies of mifepristone have also been expanding to the fields of endometriosis and uterine fibroids. Furthermore, this initially considered reproductive medicine has been investigated in some psychotic diseases and various disorders of hypercortisolism, because of its glucocorticoid receptor antagonism. Mifepristone was approved suitable for patients with hyperglycemia secondary to Cushing's syndrome by the United States Food and Drug Administration (FDA) in 2012. The aim of this article is to review published reports on the anti-progesterone and anti-glucocorticoid properties of mifepristone as a clinical agent. There is a new insight into systematically describing and evaluating the potential efficiency of mifepristone administrated in the field of endocrine and neuroendocrine, not only in obstetrics and gynecology.

Developments in contraception

INTRODUCTION

Although the contraceptive options for women have expanded considerably in the last decade, these methods are often not being offered to women as choices because clinicians are not well informed, limiting the ability of women to control their fertility.

AREAS COVERED

Areas covered include the use of oestradiol instead of ethinyl oestradiol and improved progestogens utilised in hormonal contraceptives, and new delivery systems have enabled the development of long-acting methods, which require less action on the part of the user, and thereby, reduce failure rates. Effective emergency contraceptive methods have become more readily available over the counter. However, male contraception, despite much research, still remains elusive.

EXPERT OPINION

This manuscript will provide an assessment of recent advances and controversies in contraception and make suggestions about improved availability.