The effectiveness of the morning-after pill could be compromised by a woman's weight, the Associated Press reported.
The European Medicines Agency announced Friday that it has started a review of emergency contraceptives to see whether increased bodyweight and body mass index (BMI) reduces the effectiveness of the medicine.
"This is an efficacy issue," Monika Benstetter, a spokeswoman for the EMA, told the AP. "We need to find out what the association is with BMI and if there is a cut-off threshold for when the medicine becomes less effective."
The French drug maker HRA Pharma announced in November that its morning-after pill Norlevo was less effective in women who weighed more than 165 pounds and was completely ineffective in women who weighed more than 176 pounds. After consulting with European drug regulators, HRA Pharma changed its labels to warn patients, the AP reported.
The EMA said it would evaluate new data suggesting that a high bodyweight could impair the effectiveness of emergency contraceptives.
The emergency contraceptives being reviewed include a number of medicines authorized at the national level that contain the progestogen (hormone) levonorgestrel, such as Norlevo, Levonelle/Postinor and Levodonna.
The U.S. Food and Drug Administration said it is also studying the issue.
Emergency contraceptives can be used up to 72 hours after unprotected sex or contraceptive failure. They usually contain a higher dose of the hormone in regular birth control pills and works "by preventing ovulation or fertilization of an egg," the AP reported.
The review on emergency contraceptive is being conducted by the Committee for Medicinal Products for Human Use, the committee responsible for all questions concerning medicines for human use.
