November 26, 2013 — FDA is reviewing reports that an active ingredient in the most widely used emergency contraceptives begins losing effectiveness in women who weigh more than 165 pounds, NPR's "Shots" reports (Rovner, "Shots," NPR, 11/26).
The review comes after Mother Jones reported on Monday that European regulators approved a label change for the EC pill Norlevo because its manufacturer said it is completely ineffective for women who weigh more than 176 pounds and not fully effective in women who weigh at least 165 pounds (Redden , Mother Jones, 11/25).
Norlevo, made by HRA Pharma, is not available for sale in the U.S. However, several FDA-approved EC products -- including the one-pill versions My Way, Next Choice One Dose and Plan B One-Step, as well as some generic two-pill versions -- have the same dosage and chemical makeup as Norlevo, according to Mother Jones.
The drugs all contain the active ingredient levonorgestrel. In the U.S., Plan B One-Step is the only EC product available without a prescription to women of all ages (Redden , Mother Jones, 11/25). Levonorgestrel prevents pregnancy by interfering with ovulation so an egg cannot be fertilized (Wilson, CNN, 11/26).
"The FDA is currently reviewing the available and related scientific information on this issue, including the publication upon which the Norlevo labeling change was based," FDA spokeswoman Erica Jefferson said in an email. She added, "The agency will then determine what, if any, labeling changes to approved emergency contraceptives are warranted."
FDA requires generic drugs to have the same labels as their brand-name counterparts, meaning that generic EC products cannot change their labels unless Teva Pharmaceuticals, which makes the brand-name pill Plan B One-Step, does so.
FDA has the authority to order companies to change their labels. The agency also may request information from Teva if a generic drugmaker provides FDA with new data to review.
Jefferson said, "Both brand and generic drug manufacturers have an ongoing obligation to ensure their product labeling is accurate and up to date," adding, "When new information becomes available that causes information in drug product labeling to be inaccurate, both brand and generic drug application holders must take steps to change the content of their product labeling" (Redden , Mother Jones, 11/25).
The new information on EC's lower effectiveness in women over 165 pounds came to light through a broader study that compared different types of EC, NPR's "Shots" reports.
Study co-author Diana Blithe, a contraceptive researcher at the National Institute of Child Health and Human Development, said researchers were somewhat surprised by the finding, which "wasn't obvious ... until you had enough numbers of women in a population when you have a substantial number of women who are obese to really do that analysis" ("Shots," NPR, 11/26).
According to CDC, the average U.S. women weighs about 166 pounds, while the average weight among non-Hispanic black women in the U.S. is 186 pounds (Redden , Mother Jones, 11/25). Nearly two-third of U.S. women are considered overweight or obese.
Linda Prine, medical director of the Reproductive Health Access Project and a practicing physician, said she has had "many patients" who are overweight report that they became pregnant after using EC. Nonetheless, she found the new data surprising and noted that too few women know about the problem ("Shots," NPR, 11/26).
It is unclear if drugmakers can develop an effective levonorgestrel pill for women who weigh more than 165 pounds. A spokesperson for HRA Pharma said a dose increase in the compound "is not proven to be a solution for this problem" (Redden , Mother Jones, 11/25).