By Maggie Gorini
In June, the Food and Drug Administration (FDA) approved bremelanotide (brand name Vyleesi) to treat a lack of sexual desire in premenopausal women.1 The NWHN advocated against the drug’s approval, and spoke in opposition when the approval announcement was made. Here’s why.
Bremelanotide is designed to treat “hypoactive sexual desire disorder” on an “as-needed” basis. A woman takes it about 45 minutes before she expects to engage in sexual activity. The drug has to be injected, and comes with an auto-injector device. Bremelanotide works by affecting hormones in the brain, specifically by stimulating receptors for the hormone melanocortin-4.2 This hormone is involved with social and sexual behaviors, as well as other bodily functions. The mechanism by which bremelanotide actually influences desire is not known at this time.
Does It Work?
Bremelanotide’s effectiveness was evaluated in a controlled clinical trial of 1,202 18-to-56-year-old premenopausal women in stable relationships who reported having low or no desire for sex for at least 6 months, and had no other identified reason for their lack of desire (i.e., psychological, gynecological, or urological health concerns). The majority (86%) were white, 12% were Black, and 1% identified as a different race/ethnicity.
These women were randomized to receive either 1.75 mg of bremelanotide or placebo, and then followed for six months. The women reported back about their increased levels of desire and distress over their lack of desire on a five-point scale, which ranged from “no/none” to “very high/almost always.”3 4
The results were not impressive. On average, women who received bremelanotide reported an increase in desire of a mere 0.3 – 0.4 points on the 1-5 scale.5 6 To put it another way, approximately 25% of the woman who received of bremelanotide reported an increase in desire of at least 1 point, compared to 17% of those taking the placebo.7 8 That means that only 8% of the woman experienced a modest improvement in their level of desire as a result of the drug.
The women’s distress about their lack of sexual desire were determined by patient-reported answers to a single question. Distress decreased modestly: averages were 0.3 points lower in the bremelanotide group than the placebo group.9 So, 35% of women taking bremelanotide experienced a reduction in distress of at least 1 point, compared to 31% of women taking the placebo.10 This means that only 4% of women felt less distressed as a result of taking the drug.
The drug had no effect on the average number of satisfying sexual events reported by the women.
Are These Results Meaningful?
The manufacturer claims that these results are clinically meaningful. From the limited data currently available, we can’t assess whether the women themselves felt the same. We do know that nearly 40% of the women in the bremelanotide group dropped out, compared to fewer than 20% of women in the placebo group.11 Researchers have stated that exit surveys indicate the women valued the drug, but the researchers have yet to report the results from the full group; only 242 women completed the exit surveys out of the 1,202 women who participated in the trial.12
It is also important to note that the homogenous population (i.e., majority white) limits how generalizable these outcomes are, and also limits our understanding of risks and common side effects.
Side Effects & Complications
One reason so many women may have dropped out of the bremelanotide arm is the side effects they experienced. Forty percent of those taking bremelanotide experienced nausea, for example.13 Other common side effects include vomiting, temporary skin reddening, injection site reactions, and headaches. Specifically due to reactions like these,14 18% of subjects taking bremelanotide dropped out of the study, compared to 2% of women taking the placebo.
A very small percentage (1%) of participants reported experiencing skin and gum darkening; in about half of these cases, the darkening did not fade after they stopped treatment. Women with darker skin experienced this side effect more often than those with lighter skin.15
The drug increases the risk of high blood pressure. For this reason, the FDA label states that women shouldn’t take more than 1 dose per 24 hours, and shouldn’t take the drug more than 8 times a month, to reduce high blood pressure risks. And, the FDA recommends that those with uncontrolled hypertension or cardiovascular disease should not take the drug at all.
The study also explored how the drug interacted with hormonal contraception and alcohol. Women using hormonal contraceptives and bremelanotide did not show a statistically significant increase in their level of sexual desire.16
According to a very small controlled trial, drinking alcohol while taking bremelanotide doesn’t cause ill effects, which was tested using the equivalent of consuming three glasses of wine.17 18 This is a notable improvement over a previously approved sex-drive medication. (The study was conducted in 12 men & 12 women; yes, half the group was men.)
We lack information about how bremelanotide affects breast milk or the health of pregnant people, but no level of the drug has been deemed safe for pregnant people. Right now, we only have animal studies suggesting that extremely high exposures to the drug can lead to developmental impairments and other fetal harm (studies on pregnant animals showed harm at 125 times the human dose in mice, and at 16 times the human dose in dogs).19
Very limited data about the full clinical trial results have been published, raising significant questions. For example, hundreds of women who enrolled in the pivotal trials do not seem to be included in the company’s presentation of the results. It is unclear what happened to all of them, although we know some chose to stop after trying the auto-injector. In addition, we still don’t know the answers to other critical questions, including:
- Is the increase in desire meaningful to someone who is distressed by her lack of desire?
- Are the study results valid, since only 20% of subjects completed the exit interview?
- Why did half as many women who were randomized to take bremelanotide (124 women) elect to take the drug after the trial ended, compared to the number of women who were randomized to the placebo (239 women)?20
- What is the drug’s effect on women taking medications for high blood pressure, depression, and/or anxiety, all of which can reduce sexual desire?
- What is the experience of taking the drug like for Latina, Indigenous or Asian women, who were not part of the study trial?
- Should we be concerned that the researchers who conducted most of the studies on bremelanotide are largely funded by, and partners of, the sponsor company?
The NWHN’s Recommendation
We are disappointed by the FDA’s approval of bremelanotide and recommend that women avoid using the drug until we know more about its safety and effectiveness. We lack sufficient information for women to make informed decisions about whether the drug is safe or effective. Bremelanotide needs more scrutiny. Women need more information. The FDA had it in its power to accomplish both. We are frustrated that the FDA approved this product without providing women with the assurance they deserve that bremelanotide is safe and effective. Women deserve better.
If you are worried about your level of desire, and wonder if your symptoms warrant intervention, we recommend considering other approaches to sexual satisfaction first, at least until more safety and efficacy data are available about this drug. If you choose to use bremelanotide, we strongly recommend following the guidelines in the FDA label.21
Maggie Gorini was the most recent NWHN Policy Fellow