A nonhormonal model for emergency contraception: prostaglandin synthesis inhibitor effects on luteal function and lifespan, a pilot study

Activin A upregulates PTGS2 expression and increases PGE2 production in human granulosa-lutein cells

Activin A is one of the members of transforming growth factor-β superfamily that is expressed in human large luteal cells, and may act in an autocrine/paracrine manner to regulate luteal function. Prostaglandin-endoperoxide synthase 2 (PTGS2) enzyme and its derivative, prostaglandin E2 (PGE2), play significant roles in the regulation of corpus luteum formation and maintenance. To date, whether activin A can induce the expression of PTGS2 and the production of PGE2 in human granulosa-lutein cells is largely unknown. The aim of this study was to examine the effects of activin A on the regulation of PTGS2 expression and PGE2 production in human granulosa-lutein cells, and to investigate the underlying signal transduction mechanisms. In this study, the immortalized (SVOG cells) and primary human granulosa-lutein cells were used as the cell models. A TGF-β/activin type I receptor inhibitor, SB431542 and small interfering RNAs were used to investigate the activin A-induced downstream signaling pathway. We have demonstrated that activin A upregulated the expression of PTGS2 and increased the production of PGE2 via an ACVR1B-mediated SMAD2/3–SMAD4 signaling pathway. Our results suggest that activin A may be involved in the modulation of human corpus luteum formation via the induction of PTGS2 expression and PGE2 production.

Emergency contraception: What is new?

Unintended pregnancy rates remain high throughout the World and increase the risk of poor maternal and infant outcomes. Most of unintended pregnancies occur in women who were not using contraception or who became pregnant despite the reported use of contraception. Women who have had recent unprotected intercourse including those who have had another form of contraception fail are potential candidates for this intervention. Currently used emergency contraceptive methods are pills that contain combined estrogen-progesterone, only progestin, antiprogestins and copper intrauterine devices. The most common form of this type of contraception is oral progestin-only pills (levonorgestrel). The most effective method is copper intrauterine devices followed by anti-progestins and oral progestin-only pills. The major pathogenesis of oral emergency contraceptives is the prevention or delay of ovulation. Although conception is possible on only a few days of the cycle, emergency contraception is offered when indicated without regard to the timing of the menstrual cycle because of uncertainty in the timing of the ovulation. Levonorgestrel and E/P regimes are most effective as soon as possible after unprotected sexual intercourse. A linear relationship has been shown between effectiveness and the time of dose. The effectiveness continues for 120 h, but it is recommended to be used within 72 h after intercourse. Intrauterine devices may prevent pregnancy when 5 d after ovulation.

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.

New and emerging contraceptives: a state-of-the-art review

Background

The first hormonal contraceptive was introduced onto the market in several countries 50 years ago; however, the portfolio of contraceptive methods remains restricted with regards to their steroid composition, their cost, and their ability to satisfy the requirements of millions of women/couples in accordance with their different reproductive intentions, behaviors, cultures, and settings.

Methods

A literature review was conducted using Medline, Embase, and Current Contents databases, up to September 1, 2013 to identify publications reporting new contraceptives in development using combinations of the search terms: contraception, contraceptives, oral contraceptives, patch, vaginal ring, implants, intrauterine contraceptives, and emergency contraception (EC). Also, several experts in the field were also consulted to document ongoing projects on contraception development. Additionally, the Clinicaltrial.gov website was searched for ongoing studies on existing contraceptive methods and new and emerging female contraceptives developed over the past 5 years. Information was also obtained from the pharmaceutical industry.

Results

Early sexual debut and late menopause means that women may require contraception for up to 30 years. Although oral, injectable, vaginal, transdermal, subdermal, and intrauterine contraceptives are already available, new contraceptives have been developed in an attempt to reduce side effects and avoid early discontinuation, and to fulfill women’s different requirements. Research efforts are focused on replacing ethinyl-estradiol with natural estradiol to reduce thrombotic events. In addition, new, less androgenic progestins are being introduced and selective progesterone receptor modulators and new delivery systems are being used. In addition, research is being conducted into methods that offer dual protection (contraception and protection against human immunodeficiency virus transmission), and contraceptives for use “on demand.” Studies are also investigating non-hormonal contraceptive methods that have additional, non-contraceptive benefits.

Conclusion

The most pressing need worldwide is, first, that the highly effective contraceptive methods already available should be affordable to most of the population and also that these methods should fulfill the needs of women of different ages and with different reproductive requirements. The development of new contraceptive methods should also take advantage of the knowledge obtained over the past 30 years on gamete physiology and gamete interaction to avoid the use of steroid compounds.

Impact of the prostaglandin synthase-2 inhibitor celecoxib on ovulation and luteal events in women

BACKGROUND

Ovarian prostaglandins are critical in normal ovulation processes; thus, their inhibition may provide contraceptive benefits. This study was performed to determine the effect of the cyclooxygenase-2 (COX2) inhibitor celecoxib on ovulation and luteal events in women.

STUDY DESIGN

The study had a randomized, double-blind, crossover design. Ovulatory, reproductive-aged women underwent ovarian ultrasound and serum hormone monitoring during four menstrual cycles (control cycle, treatment cycle 1, washout cycle, treatment cycle 2). Subjects received study drug (oral celecoxib 400 mg or placebo) either (a) once daily starting on cycle day 8 and continuing until follicle rupture or the onset of next menses if follicle rupture did not occur [pre-luteinizing hormone (LH) surge dosing] or (b) once daily beginning with the LH surge and continuing for 6 days (post-LH surge dosing). Subjects were randomly assigned to one of the above treatment schemes and received the other in the subsequent treatment cycle. The main outcomes were evidence of ovulatory and luteal dysfunction as determined by inhibited/delayed follicle rupture and reduced luteal progesterone synthesis or lifespan, respectively.

RESULTS

A total of 20 women enrolled and completed the study (Group 1=10, Group 2=10), with similar demographics between groups. Nineteen subjects exhibited normal ovulation in the control cycle (one had a blunted LH peak). In comparison to control cycles, treatment cycles resulted in a significant increase in ovulatory dysfunction [pre-LH treatment: 30% (6/20), p=.04; post-LH treatment: 25% (5/20), p=.04]. Mean peak progesterone, estradiol, and LH levels and luteal phase length did not differ significantly between control and either treatment cycle.

CONCLUSIONS

Although treatment with celecoxib before or after the LH surge increases the rate of ovulatory dysfunction, most women ovulate normally. Thus, this selective COX2 inhibitor appears to be of limited usefulness as a potential emergency contraceptive.