Emergency contraception: a review of current oral options

Emergency Contraception: Access and Challenges at Times of Uncertainty

BACKGROUND

The UN Commission on Life-Saving Commodities for Women's and Children's Health identified emergency contraceptive pills as 1 of the 13 essential underused, low-cost, and high-impact commodities that could save the lives of millions of women and children worldwide. In the US, 2 emergency contraceptive regimens are currently approved, and their most plausible mechanism of action involves delaying and/or inhibiting ovulation.

AREAS OF UNCERTAINTY

Abortion and contraception are recognized as essential components of reproductive health care. In the US, in the wake of the Dobbs v. Jackson Women's Health Organization Supreme Court decision on June 24, 2022, 26 states began to or are expected to severely restrict abortion. It is anticipated that these restrictions will increase the demand for emergency contraception (EC). Several obstacles to EC access have been described, and these include cost, hurdles to over-the-counter purchase, low awareness, myths about their mechanisms of action, widespread misinformation, and barriers that special populations face in accessing them. The politicization of EC is a major factor limiting access. Improving sex education and health literacy, along with eHealth literacy, are important initiatives to improve EC uptake and access.

DATA SOURCES

PubMed, The Guttmacher Institute, Society of Family Planning, American College of Obstetrician and Gynecologists, the World Health Organization, The United Nations.

THERAPEUTIC ADVANCES

A randomized noninferiority trial showed that the 52 mg levonorgestrel intrauterine device was noninferior to the copper intrauterine device when used as an EC method in the first 5 days after unprotected intercourse. This is a promising and highly effective emergency contraceptive option, particularly for overweight and obese patients, and a contraceptive option with a different bleeding profile than the copper intrauterine device.

CONCLUSIONS

EC represents an important facet of medicine and public health. The 2 medical regimens currently approved in the US are very effective, have virtually no medical contraindications, and novel formulations are actively being investigated to make them more convenient and effective for all patient populations. Barriers to accessing EC, including the widespread presence of contraception deserts, threaten to broaden and accentuate the already existing inequities and disparities in society, at a time when they have reached the dimensions of a public health crisis.

Molecular cues to the anti-implantation effect of nano-puerarin in rats

Puerarin, a selective oestrogen receptor modulator, intercepts implantation in rats, albeit at unacceptably higher doses. We developed poly lactic-co-glycolic acid-encapsulated nano-puerarin (PN) and mapped the molecular pathway underlying its anti-implantation effects. Smooth-surfaced and spherical PN having a mean diameter of ∼147nm was obtained with good yield, efficient encapsulation, and optimum drug loading. In culture, PN slowly and steadily released puerarin, which was readily taken up by the decidual cells. PN exerted a dose-dependent anti-implantation effect. As marked by attenuated expression of stromal cell desmin, alkaline phosphatase, IGFBP1, and decidual prolactin-related protein, the anti-implantation effect of PN seemed secondary to compromised decidualization. Usingin vivo(pregnant and pseudopregnant rats) andin vitro(endometrial stromal cell culture) treatment models, we document that PN enforced inhibition of uterine expression ofHbegfandHoxa10and their downstream signalling molecules, Cyclin D3 (CCND3)/CDK4. PN also efficiently ablated theIhh-Nr2f2-Bmp2signalling pathway and invited the loss of uterine potential for decidualization. There was a dose-dependent up-regulation of RHOA and its effector protein kinase, ROCK1, leading to the promotion of MLC phosphorylation and actin–myosin interaction. PN also down-regulated the stromal cell activation of ERK½ and expression of MMP9. These effects acting together stabilized the stroma and inhibited the stromal cell migration. Central to this array of events was the adversely altered endometrial expression of oestrogen receptor subtypes and repression of progesterone receptor that indulged endless proliferation of luminal epithelia and distorted the precisely choreographed stroma–epithelia crosstalk. Thus, PN dismantles the endometrial bed preparation and prevents implantation.

Puerarin, a selective oestrogen receptor modulator, disrupts pregnancy in rats at pre-implantation stage

The tubers ofPueraria tuberosahave folkloric repute as emmenagogue. The n-BuOH fraction of the ethanolic extract of tubers exhibits significant antifertility activity in laboratory animals. The present investigation explored the active principle(s) of the tuber extract with reference to contragestive effects in rats and probed the possible mechanism of action. Bioactivity-guided fractionation identified puerarin as the major constituent that exerted pregnancy-terminating effects. Oral administration of puerarin at ≥300 mg/kg per day for days (D) 1–2 post-coitus resulted in complete implantation failure. Serum oestradiol levels during D2–D5 and progesterone (P4) level on D5 remained unaffected, but the endometrial expression of oestrogen receptor α (ERα) and ERβ was adversely modulated that disrupted the implantation-specific characteristic endometrial oestrogenic milieu. The eventual consequence was loss of endometrial receptivity characterised by down-regulation of the uterine expression of P4receptor (PR) and attenuation of endometrial expression of leukaemia inhibitory factor, vascular endothelial growth factor and cyclo-oxygenase-2, the three important signalling molecules involved in the process of implantation. Light microscopic examination of the embryos demonstrated no untoward effect of puerarin on the development of embryos until D4, but D5 blastocysts underwent gross morphological distortion. The findings taken together are interpreted to suggest that puerarin adversely impacts the uterine expression of ER and PR that disrupts the implantation-conducive uterine milieu and prevents implantation. In conclusion, puerarin may be envisaged as a prospective molecule that merits further exploration for the development of non-steroidal post-coital contraceptive for women.

Enhancing contraception A comprehensive review

This review covers familiar and emerging contraceptive methods, comparing the risks and benefits of each. These basics will help you connect patients with the most acceptable form of contraception for them.