Mechanisms of Action of Hormonal Emergency Contraceptives

@article{Leung2010MechanismsOA,
  title={Mechanisms of Action of Hormonal Emergency Contraceptives},
  author={Vivian W. Y. Leung and Marc Levine and Judith A. Soon},
  journal={Pharmacotherapy: The Journal of Human Pharmacology and Drug Therapy},
  year={2010},
  volume={30}
}
  • V. Leung, M. Levine, J. Soon
  • Published 1 February 2010
  • Medicine
  • Pharmacotherapy: The Journal of Human Pharmacology and Drug Therapy
Hormonal emergency contraceptives have been used to prevent unwanted pregnancy for more than 3 decades. The mechanisms of action of the regimen containing a combination of estrogen and progestin, known as the Yuzpe regimen, and those of the levonorgestrel regimen continue to be controversial, especially over the possibility that these regimens might act by interfering with implantation of the fertilized ovum. We performed a search of the PubMed (1949‐July 2009) and EMBASE (1980‐July 2009… 
[Effect of levonorgestrel in the ovulation, endometrium, and spermatozoa for emergency oral contraception].
TLDR
The main mechanism of action of the levonorgestrel, given at the doses recommended for EOC, is the inhibition or retardation of the ovulation, it doesn't affect the spermatozoa in their migration or egg-penetration capacities and no morphological or molecular alterations in the endometrium that could interfere with the implanted egg have been demonstrated.
Emergency Contraception: Review and Update
TLDR
The most effective postcoital method of contraception is the copper intrauterine device (IUD).
Efecto del levonorgestrel como anticonceptivo oral de emergencia en la ovulación, el endometrio y los espermatozoides
TLDR
It is found that the main mechanism of action of the levonorgestrel, given at the doses recommended for EOC, is the inhibition or retardation of the ovulation, it doesn’t affect the spermatozoa in their migration or egg-penetration capacities, and no morphological or molecular alterations in the endometrium that could interfere with the implanted egg have been demonstrated.
Efficacy and safety of a levonorgestrel enteric-coated tablet as an over-the-counter drug for emergency contraception: a Phase IV clinical trial
TLDR
The study found that E-LNG-ECP was effective, safe and well tolerated as an over-the-counter drug for emergency contraception in Chinese women, and an randomized controlled trial should be performed to compare standard LNG tablets with E- LNG- ECP.
Evaluation of the Mechanism of Action of Anti-fertility Treatment in Cases of Sexual Assault: Moral Certitude and Human Acts
TLDR
Current rape treatment protocols are grossly inadequate and fail to provide moral certitude precluding embryocide, and careful assessment of the scientific corpus cannot rule out significant post fertilization MOA and cannot establish the minimum level of confidence necessary formoral certitude that it is not abortifacient.
Ulipristal acetate: a new emergency contraceptive
Ulipristal acetate (UPA) is a newly developed emergency contraceptive currently available in the USA and Europe. It is approved as a 30 mg one-time dose taken within 120 h (5 days) of unprotected
Emergency contraception: an unresolved issue.
Conocimientos, actitudes y prácticas de profesionales en farmacia sobre la anticoncepción hormonal de emergencia (PAE) en Costa Rica = Knowledge, attitudes and practices of professionals in pharmacy on hormonal contraception emergency (ECP) in Costa Rica
TLDR
It is concluded that, despite the high level of knowledge, low prescription of emergency contraception is related to low awareness of the existing evidence of its mechanism of action.
Oral contraceptive pills: Risky or protective in case of Trichinella spiralis infection?
TLDR
Oestrogen‐containing pills established a favourable intestinal environment for Trichinella by enhancing Foxp+T‐reg.
...
...

References

SHOWING 1-10 OF 84 REFERENCES
Mechanism of action of emergency contraceptive pills.
Postfertilization Effect of Hormonal Emergency Contraception
TLDR
Both the Yuzpe regimen and Plan B likely act at × by causing a postfertilization effect, regardless of when in the menstrual cycle they are used, with potential implications in such areas as informed consent, emergency department protocols, and conscience clauses.
Controversies in contraception
TLDR
It is suggested that Depo-Provera and, perhaps, low-dose oral contraceptive pills can have adverse effects on adolescent bone health, although the data demonstrating reversibility of bone loss after discontinuation of these contraceptives are reassuring.
Effect of the Yuzpe regimen of emergency contraception on markers of endometrial receptivity.
TLDR
Five statistically significant changes were noted in treated cycles: a reduction in endometrial MUC-1 expression, an increase in Endometrial Oestrogen receptor, lower luteal phase serum oestrogen concentration, reducedendometrial thickness, and greater proportion of glandular supranuclear vacuoles.
Levonorgestrel emergency contraception: a joint analysis of effectiveness and mechanism of action.
...
...