The Medical Letter on Drugs and Therapeutics
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1355
Ella: A New Emergency Contraceptive
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The FDA has approved the use of ulipristal acetate (ella – Watson) as an emergency contraceptive that can be taken up to 5 days after unprotected intercourse. It is available only by prescription.

MECHANISM OF ACTION — Ulipristal acetate, a progesterone-receptor agonist/antagonist structurally similar to mifepristone (Mifeprex), when taken immediately before ovulation has been shown to delay follicular rupture.1 It may also cause endometrial changes that could interfere with implantation of a fertilized ovum.

PROBABILITY OF PREGNANCY — The probability of pregnancy after unprotected intercourse has been estimated to be about 15% when coitus occurs 3 days before ovulation, 30% 1 or 2 days before ovulation, and 12% on the day of ovulation.2 One or 2 days after ovulation, the probability of pregnancy ... more      

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Title: Ella: A New Emergency Contraceptive
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