Fran Lowry

June 29, 2015

MIAMI — For men with sexual dysfunction, sildenafil (Viagra, Pfizer Inc) has been available for the past 18 years. Now, women who have problems with sexual function may have their own drug, researchers say.

Bremelanotide (BMT), a novel heptapeptide melanocortin-receptor-4 agonist, given subcutaneously, yielded improvements in the number of satisfying sexual events, frequency, and intensity of desire and a reduction in distress over level of sexual desire, according to the results of a phase 2B dose-ranging study presented here at the American Society of Clinical Psychopharmacology (ASCP) 2015 Annual Meeting.

"It has been difficult to find a drug to help women with sexual dysfunction, and we've really not had anything, because you're talking about desire," lead author Anita H. Clayton, MD, from the University of Virginia, in Charlottesville, told Medscape Medical News.

"From a psychiatrist's perspective, it's like studying depression. Women tell you what their symptoms are, but there is no blood test for sexual dysfunction, and it's harder to measure desire than it is an erection," Dr Clayton said.

"Part of the problem has been deciding what measures to use for outcomes. I think that now, with this study that shows effectiveness at every endpoint with a particular drug, it will move it forward. If the FDA does go ahead and approve flibanserin for hypoactive sexual desire, and the advisory committee recommended it 18 to 6 earlier in June, I think you'll see more interest and money flowing to try to evaluate this area. It is an area of desperate need; 10% of the US population of women has hypoactive sexual desire disorder," she said.

Dr Anita Clayton

Dr Clayton and her group assessed the use of subcutaneous BMT in 327 premenopausal women (mean age, 36 years) diagnosed with hypoactive sexual desire disorder (HSDD), which is distressing low sexual desire, female sexual arousal disorder (FSAD), which is distressing low or absent genital arousal, or both conditions, lasting for at least 6 months.

Of these women, 281 either had solely HSDD (n = 75) or had mixed HSDD/FSAD in which the primary diagnosis was HSDD (n = 206).

For 4 weeks, the women received single-blind, at-home, self-administered placebo, after which they were randomly assigned to receive double-blind placebo or BMT 0.75 mg, 1.25 mg, or 1.75 mg, self-administered for 12 weeks.

Outcomes included changes from baseline to end of study in the number of satisfying sexual events (SSEs) and improvements in scores on the Female Sexual Function Index (FSFI) and the Female Sexual Distress Scale–Desire/Arousal/Orgasm (FSDS-DAO).

Bremelanotide yielded improvements in the number of SSEs and improvements in FSFI and FSDS-DAO scores, Dr Clayton said.

With regard to SSEs, the mean (standard deviation [SD]) improvement from baseline to end of study was +0.2 SSEs per month for placebo, compared with +0.8 for BMT 0.75 mg, +0.7 for BMT 1.25 mg, and +0.7 for BMT 1.75 mg.

With regard to improvement in the FSFI total score, the mean SD improvement from baseline to end of study was +1.55 for placebo vs +1.45 for BMT 0.75 mg, +3.1 for BMT 1.25 mg, and +4.2 for BMT 1.75 mg.

With regard to FSDS-DAO total score, the mean change was -6.6 with placebo, compared with -8.0 for BMT 0.75 mg, -9.6 for BMT 1.25 mg, and -12.7 for BMT 1.75 mg.

When the women were receiving bremelanotide, they also reported that they were less bothered by low desire, Dr Clayton said.

"We found that the lowest dose of BMT was not that effective, which is good to know. However, BMT benefit was statistically significant, with a P-value less than 0.5, at the 1.75 mg dose on all outcomes that we measured," she said.

Long Overdue

"Sexual dysfunction in women is common, affecting about 10% of the population. Until recently, there has been little attention paid to female sexual interest/arousal disorders from the pharmaceutical industry, in part related to the complexity of defining the disorders in women and difficulty defining relevant endpoints for FDA approval," Holly A. Swartz, MD, professor, University of Pittsburgh School of Medicine, in Pennsylvania, told Medscape Medical News.

"The FDA has been actively engaged in developing a framework for regulating drugs for low sexual desire/interest/arousal in women," said Dr Swartz, who was not involved in the study.

Dr Holly Swartz

"In fact, Dr Christina Chang from the FDA chaired a symposium on this topic at ASCP. Dr Clayton's study provides evidence supporting a new treatment that addresses low sexual desire and/or low arousal in premenopausal women. Viagra was developed to address the sexual health of men and became a cultural touchstone; there has not been a comparable intervention to address the sexual health of women. Attention to this issue is certainly overdue. Although not yet approved by FDA, this work is helping to address the gender gap in our clinical armamentarium for addressing sexual disorders," Dr Swartz said.

The study was funded by Palatin Technologies, Inc. Dr Clayton reports financial relationships with Ballantine Books/Random House, Changes in Sexual Functioning Questionnaire, Guilford Publications, BioSante, Euthymics, Forest Research Institute, Inc, Lundbeck, Palatin Technologies Inc, Pfizer, S1 Biopharmaceuticals Inc, Sprout Pharmaceuticals, Takeda Global Research and Development, and Trimel Pharmaceuticals, Inc. Dr Swartz reports no relevant financial relationships.

American Society of Clinical Psychopharmacology (ASCP) 2015 Annual Meeting. Abstract 3000393. Presented June 23, 2015.

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