A European manufacturer of an emergency contraceptive pill identical in chemical composition to Plan-B One Step and other generic brands has issued an alarming warning about the effectiveness of the morning-after pill in women who weigh more than 165 pounds.
According to HRA Pharma, the French manufacturer of the emergency contraceptive Norlevo, the drug begins to lose its effectiveness for women who weigh more than 165 pounds and is completely ineffective for women who weigh more than 176 pounds. European pharmaceutical regulators have updated the packaging of the drug to reflect the weight limits.
Norlevo is sold throughout Europe, Australia, parts of China and Africa and elsewhere in the world, but this news, if true, also has major implications for women who take emergency contraceptive pills identical in chemical makeup and dosage to Norlevo in the United States.
More from Molly Redden at Mother Jones:
Some of the most popular emergency contraceptive pills sold over-the-counter in the United States — including the one-pill drugs Plan B One-Step, Next Choice One Dose, and My Way, and a number of generic two-pill emergency contraceptives — have a dosage and chemical makeup identical to the European drug. Weight data from the Centers for Disease Control suggests that at 166 pounds, the average American woman is too heavy to use these pills effectively.
Data for the years 2007 to 2010 show the average weight of American women 20 years and older is 166.2 pounds—above the weight at which emergency contraceptive pills that use levonorgestrel begin to lose their effectiveness. The average weight of non-Hispanic black women aged 20 to 39 is 186 pounds, well above the weight at which these pills are completely ineffective. A CDC surveypublished in February found that 5.8 million American women used emergency contraceptive pills from 2006 to 2010.
But American manufacturers do not currently advise American customers of weight limits for levonorgestrel-based emergency contraceptives.
Because the Food and Drug Administration prohibits generic drug manufacturers from changing product information unless the brand name manufacturer makes a change, companies that manufacture generic versions of Plan B One-Step cannot update their packaging information unless Teva Pharmaceutical Industries, the exclusive manufacturer of Plan B One-Step, acts first. (The FDA has proposed a rule change that would allow generic manufacturers to update drug information independently.) A spokeswoman for Teva declined to comment for this article.