EU regulators say that two emergency contraceptive drugs, levonorgestrel and ulipristal, remain effective for their prescribed purpose "regardless of bodyweight," placating some—but not all—concerns that the drugs might lose effectiveness when taken by women weighing more than 80kg (176 lbs).

Background

In November 2013, Mother Jones broke the news that HRA Pharma, manufacturer of the emergency contraceptive Norlevo, a levonorgestrel-based emergency contraceptive, was updating its packaging to reflect new evidence that the drug begins to lose effectiveness in overweight women, and may lose all effectiveness in women who are obese.

Norlevo is similar to the levonorgestrel-based emergency contraceptive Plan B, which is widely marketed in the US and available over the counter (OTC).

In the wake of the revelations, the US Food and Drug Administration (FDA) said it would review the evidence to determine if labeling changes were needed for levonorgestrel-based emergency contraceptives.

"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 reportedly told news outlets in an email. "The agency will then determine what, if any, labeling changes to approved emergency contraceptives are warranted."

EMA Initiates Review

Shortly after FDA announced that it would review the efficacy of the medicines, the European Medicines Agency (EMA) announced that it, too, would review marketed emergency contraceptive products to determine if they lost effectiveness in heavier women.

EMA said that data indicated that the drugs lost effectiveness in women weighing more than 75kg, and all effectiveness in women weighing more than 80kg.

However, after a nine-month review, EMA regulators now say that "all the available evidence on the effectiveness of emergency contraceptives" (HRA Pharma's Norlevo and Bayer's Levonelle) have not substantiated their concerns.

"The Agency’s Committee for Medicinal Products for Human Use (CHMP) recommends that these emergency contraceptives can continue to be used in women of all weights as the benefits are considered to outweigh the risks," the regulator wrote in a 24 July 2014 statement.

Limited Evidence

Which isn't to say that "all the available evidence" was enough to totally invalidate the regulators' concerns.

EMA said that its regulators found that "the data available are too limited and not robust enough to conclude with certainty that contraceptive effect is reduced with increased bodyweight.”

EMA explained that for both medications, some data had indicated reduced effectiveness was correlated with higher body weight, but that the data was "limited" and was countered by data in other studies that did not show evidence of an effect.

"The Committee for Medicinal Products for Human Use (CHMP) recommended that the results of these studies should be included in the product information of emergency contraceptives, but that the current statements on the impact of bodyweight in the product information for Norlevo should be deleted," EMA said in a statement, adding that, "They can continue to be taken regardless of the woman’s bodyweight."

FDA has yet to announce the results of its own investigation into the drug's efficacy.

EMA Statement