Efficacy and Safety of a Levonorgestrel Enteric-Coated Tablet as an Over- the-Counter Drug for Emergency Contraception: A Phase IV Clinical Trial

The most widely used emergency contraception pill (ECP) in China is levonorgestrel (LNG), which was approved as an over-the-counter pill in 1998. An improved formulation, enteric-coated LNG-ECP (E-LNG-ECP) has been developed that improves tolerability of the drug because its absorption in the intestine rather than in the stomach is less likely to produce nausea and vomiting.This Phase IV clinical trial investigated the efficacy, safety, and acceptability of the E-LNG-ECP as an over-the-counter drug in Chinese women. The study was conducted in 5 family planning clinics between 2009 and 2010. Participants were healthy women aged between 15 and 48 years who sought ECP within 72 hours of unprotected sex or contraceptive failure. Data on efficacy and acceptability were obtained through patient interviews at follow-up. The primary study end-point was the rate of pregnancy within 7 days after expected menses. The rate of side-effects and tolerability of the drug also was analyzed.Among the 2445 women who met inclusion criteria, only 5 pregnancies (0.20%) occurred. The contraceptive efficacy was 95.3%. At least one adverse event was reported in 6.5% of the participants but none was serious. Vomiting occurred in only 4 subjects (0.16%). Menstrual disturbances were common; the next menstrual cycle did not occur when expected in 20.1% of the women who took E-LNG-ECP. More than half of the participants had previously taken ECPs; these women rated the acceptability of E-LNG-ECP as 9.36 (on a 10-point scale) compared with a rating of 7.36 for other ECP pills taken previously (P < 0.05).These findings show that the E-LNG-ECP is safe and effective, with high patient acceptability.