None of those 26 drugs, though, has the same purpose as flibanserin. Viagra and its ilk enhance physical arousal; despite its nickname as the “pink Viagra,” flibanserin was developed to enhance desire. Viagra is taken before sex and increases blood flow to the genitals; flibanserin is supposed to be taken daily and aims further north, changing the balance of neurotransmitters in the brain.

The comparisons to Viagra, and the bumpy road to approval, have raised complicated questions about the nature of female desire, sexism in drug research, and what ought to qualify as a disorder.

The drug’s approval has also raised a simpler question: What changed, exactly, between those two rejections and last night?

The most obvious answer is good public relations. Even the Score, which launched in 2013, has framed the issue as one of “women’s sexual health equity.” The group notes on its site that the World Health Organization considers “[pursuit of] a satisfying, safe and pleasurable sexual life” to be a human right, and has successfully solicited letters of support to the FDA from the editor of The Journal of Sexual Medicine, the president of the National Organization for Women, and members of Congress.

In an June editorial in the Journal of the American Medical Association, three members of the FDA’s June advisory committee wrote of Even the Score: “Although flibanserin is not the first product to be supported by a consumer advocacy group [that is] in turn supported by pharmaceutical manufacturers, claims of gender bias regarding the FDA’s regulation have been particularly noteworthy, as have the extent of advocacy efforts.”

But there’s another answer, too: Between the two rejections and the approval, the benchmark for success has changed.

A highlights-only timeline of the drug’s rocky history looks like this: Flibanserin was originally developed as an antidepressant. After initial trials found it to be ineffective, it was redirected as a remedy for low female desire. The pharmaceutical company Boehringer Ingelheim submitted the drug for approval in 2010, though the agency rejected the application, noting that it didn’t seem to work very well for its new purpose, either. Sprout acquired the drug in 2011 and saw another rejection in 2013; this time, the FDA asked for additional safety studies and called for an advisory committee to investigate whether the risks outweighed the modest benefits.

Boehringer Ingelheim’s first two trials, submitted as part of the application the FDA rejected in 2010, had asked participants to keep a daily digital diary, reporting both the number of “satisfying sexual events” and the highest level of sexual desire they experienced each day. These measures were the study’s primary endpoints, or the main questions a drug trial is designed to answer. Of the two, only the number of satisfying sexual experiences slightly increased with the use of flibanserin; the pill failed to make any meaningful difference on self-reported levels of desire.