Emergency Contraceptive May Be Ineffective For Women Over 176 Pounds

December 11, 2013 | Charles Bowen

A recent announcement by a French drug company has made big news in the pharmaceutical world. HRA Pharma, maker of an emergency contraception drug known as Norlevo, has announced that its product loses effectiveness in women over 165 pounds and is completely ineffective for those who weigh more than 176 pounds.

Though the news about Norlevo may not seem of major import to Americans (given that the drug is not sold in the United States), other drugs that are chemically identical to Norlevo are sold here and the announcement raises serious questions about the effectiveness of those drugs. Experts say that the popular emergency contraceptive Plan B One-Step and its generic counterparts--Next Choice One Dose and My Way--all contain the same synthetic hormone as Norlevo which means they too may suffer similar effectiveness issues.

All four drugs contain a hormone known as levonorgestrel, something researchers at HRA Pharma began to worry about in heavier women. As a result, the company launched an investigation into the drug and the results surprised everyone. Women who weigh more than 165 pounds show a dramatic loss of effectiveness when taking the emergency contraceptive and those weighing more than 176 pounds had a complete “absence of effectiveness.” HRA Pharma says that it was alarmed by the results and decided it had an obligation to report the data to European health officials who then ordered the company to change its labeling on Norlevo to say that the product is no longer recommended for use by women who weigh more than 165 pounds.

The trouble with Norlevo has set off alarm bells in the United States and consumer safety advocates are demanding action by the FDA to determine if similar labeling changes should be implemented with regard to Plan B One-Step. The FDA so far has said it is reviewing the recent HRA Pharma study and will make a decision about possible labeling changes after it has gathered more data.

Though the news surprised many people, it’s been clear for a number of years that birth control pills also suffer serious declines in effectiveness in those weighing more than 155 pounds. Many suspect the reason is that in overweight and obese women it can take much higher levels of certain drugs for longer periods of times before the requisite concentration is reached to be effective. This is clearly a problem given that data shows that the average weight of American women 20 years and older is 166.2 pounds, heavier than the weight at which levonorgestrel begins to lose its effectiveness. African-American women between the ages of 20 and 39 have an average weight of 186 pounds, well outside the range of effectiveness. Given these troubling numbers it’s possible that millions of women who have used the drug in the past did so with little benefit.