title: The rationale for use of Ulipristal Acetate as first line in emergency contraception: biological and clinical evidence.
abstract: Ulipristal acetate (UPA) was licensed as an emergency contraceptive (EC) in Europe in 2009. By the end of May 2013, over 1.4 million courses had been used. The rationale for using UPA for EC in favor of the much more commonly used levonorgestrel (LNG) is based on data on efficacy, safety and side effects.
  
  
  RESULTS
  In two large clinical trials among women presenting for EC up to 120 hours after unprotected sex, UPA was as effective as LNG at preventing pregnancy. When the two trials were combined in a meta analysis UPA was superior, almost halving the risk of pregnancy compared with LNG. Biomedical studies have shown that UPA inhibits or delays ovulation more effectively than LNG at a stage of the cycle when the risk of pregnancy is highest. Safety and side effects: UPA and LNG have similar side effect profiles and to date no serious adverse events have been attributed to use of UPA for EC. Data on pregnancies conceived in association with UPA use are reassuring. There is no evidence for teratogenesis or for any increased risk of ectopic pregnancy or miscarriage.
  
  
  BACKGROUND
  Use of UPA will remain limited until it is available without a doctor's prescription.
authors.affiliation: Department of Obstetrics and Gynecology, University of Edinburgh , Edinburgh , UK.
authors.forename: Anna
authors.initials: A
authors.lastname: Glasier
mesh_terms: D044363:Contraception, Postcoital / Q000379:methods*; D003270:Contraceptive Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology; D005260:Female; D006801:Humans; D009649:Norpregnadienes / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology
chemical_list: D003270:Contraceptive Agents; D009649:Norpregnadienes; C555622:ulipristal acetate
keywords: Availability cost; Ulipristal acetate; efficacy; emergency contraception; safety