Plan B One-Step emergency contraception is identical to the European drug Norelvo, which has been found to be ineffective in overweight women, prompting an FDA review.
Nov. 26 (UPI) -- Norlevo, an emergency contraceptive manufactured in Europe, has been found to be ineffective in overweight women. Norlevo is identical to Plan B One-Step, which is available in the U.S.
The French manufacturer of Norlevo, HRA Pharma, has reported that in conducting additional research, scientists realized there was "a clear impact of weight" on the effectiveness of the drug. The drug began to lose its effectiveness when a women's weight reached 165 pounds and showed no effect at 176 pounds.
"We felt it was our ethical duty ... to report those results to our health authorities here in Europe," said HRA Pharma CEO Erin Gainer.
This has prompted the Food and Drug Administration to review the change in labeling on Norlevo and if any such changes were needed on U.S. brands.
Plan B is available to women without a prescription and its generic versions, Next Choice One Dose and My Way, were also similar to Norlevo. But these generic brands cannot change their labeling until the name brand, Plan B, changes its labeling. Both Norlevo and Plan B are LNG ECs, or emergency contraceptives that include levonorgestrel, a synthetic version of the hormone progestogen.
The reason for the drug's ineffectiveness in overweight women is currently unknown.
Anna Glasier, an expert in reproductive medicine at the University of Edinburgh, in 2011 studied the risks associated with taking emergency contraceptives. Her team found that obese women had three times the risk of getting pregnant after taking emergency contraceptives compared to those with normal body weight.
The risk was greater for those who had taken levonorgestrel pills, like Norlevo and Plan B, as compared to ulipristal acetate, which is used in another emergency contraceptive called Ella.
Still, some health experts believe that using the emergency contraceptive is worth a try even if there is a possibility it may not work.
"You are probably better to take LNG-EC after unprotected sex than just to leave it to chance even if you are obese," Glasier said.
"When faced with a choice ... I don't think the findings are strong enough for us to tell women that they should not use LNG-EC," said Kelly Cleland, a public health expert at Princeton University.