Some morning-after pills (also known as emergency contraceptive pills) are reportedly "not effective" for women over 176lbs (80kgs), warns drug maker HRA Pharma.
HRA Pharma, the French manufacturer of the emergency contraceptive Norlevo, has warned women weighing more than 176lbs that the pill is not effective, as well as it begins losing its effectiveness when women reach 165lbs (75 kgs).
Per CEO Erin Gainer, the manufacturer was conducting research on another topic that ties in to Norlevo when researchers realized that there was "a clear impact of weight" on the drug's effectiveness.
"We felt it was our ethical duty ... to report those results to our health authorities here in Europe," said Gainer.
The same rule may also be true of other emergency contraceptives in the U.S. Norlevo is similar to the emergency contraceptive Plan B One-Step and is frequently given the moniker the morning-after pill as it works by interfering with ovulation and preventing the fertilization of the egg. Norlevo contains levonorgestrel, which is a synthetic hormone, that blocks the fertilization if it is consumed within 72 hours of unprotected sex.
Norlevo is sold around the world and a Food and Drug Administration (FDA) spokeswoman said it "is evaluating whether to require US emergency contraceptive pill makers to change their labels."
"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," said Erica Jefferson, deputy director for the FDA office of media affairs. "The agency will then determine what, if any, labeling changes to approved emergency contraceptives are warranted."
New leaflets that warn women about weight limits are set to appear on every box of Norlevo sold in Europe in the first half of 2014. The new labeling will read:
"Studies suggest that Norlevo is less effective in women weighing [165 pounds] or more and not effective in women weighing [176 pounds] or more" and that Norlevo "is not recommended...if you weigh [165 pounds] or more."
