Topical Sildenafil for Women with FSAD
Female sexual arousal disorder (FSAD) is characterized by a persistent or recurrent inability to attain or to maintain sexual arousal until the completion of sexual activities.1 As many as thirty-three percent of women in the U.S. (21 to 60 years old) experience symptoms of low or no sexual arousal.2 Up to an estimated ten million women in the U.S. are affected and/or distressed by this condition and seek a solution to improve their condition.3
There are no approved products in the U.S. that specifically address the symptoms or underlying pathology of FSAD. Orally administered sildenafil received FDA approval in 1998 for the treatment of erectile dysfunction in men and is marketed under the brand name Viagra®. Oral sildenafil also demonstrated biological activity when studied in women,4 but due to differences between male and female physiology, it is expected that a topically administered formulation of sildenafil (applied directly to the vaginal cavity) may have advantages over the oral formulation. SST’s Topical Sildenafil formulation is a unique, proprietary topical formulation of sildenafil that is specially formulated for women in a topical cream dosage form and is designed to be applied directly to the genital tissue. Based on known biological pathways for the molecule, Topical Sildenafil is expected to increase local blood flow to the genital tissue, which we believe will lead to an improvement in genital response and overall sexual experience.
More specifically, studies of women have demonstrated that an improvement in genital blood flow is linked to increased arousal and improved sexual experience.5 Sildenafil is known to inhibit PDE5, leading to an increase in smooth muscle relaxation and improved blood flow.6 Our investigational SST Topical Sildenafil formulation is expected to exhibit similar PDE5 inhibitor effects on female genital tissue. In a Phase 2a trial in women with FSAD, SST’s Topical Sildenafil formulation demonstrated increases in measurable blood flow to the genital tissue when compared to placebo.7
We plan to request a meeting with the FDA to discuss the Phase 2 and 3 trial designs for Topical Sildenafil in FSAD patients in the first half of 2018. Currently, the planned Phase 2 trial is expected to evaluate the product candidate under real-life conditions in women with FSAD. Clinical endpoints are expected to include patient reported outcomes (PROs) using validated questionnaires, and FDA’s input will be requested on the proposed PROs and questionnaire tools as well. The objective of the Phase 2 and 3 trials is to establish the efficacy and safety of SST’s Topical Sildenafil for this proposed use in order to support future regulatory applications to bring an important new treatment for women to commercial markets.
1 Human Sexuality and Its Problems (Third Edition), 2009
2 Ad Hoc Market Research: FSAD Prevalence Report (Oct 2015) conducted for SST LLC.
3 16% of women are distressed per Ad Hoc Market Research: FSAD Prevalence Report (Oct 2015) conducted for SST LLC. Based on US Census projections for 2016 this equates to 10 million women.
4 The Enhancement of Vaginal Vasocongestion by Sildenafil in Healthy Premonopausal Women. Journal of Women’s Health & Gender-Based Medicine. Vol. 11, No. 4. 2002; The Effect of Sildenafil Citrate on Uterine and Clitoral Arterial Blood Flow in Postmenopausal Women https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1480594/
5 Safety and Efficacy of Sildenafil Citrate for the Treatment of FSAD: A Double-Blind, Placebo Controlled Study. The Journal of Urology. Vol 170, 2333-2338, December 2003.
6 Viagra® prescribing information, Mechanism of Action Section 12.1, https://www.viagra.com, https://www.accessdata.fda.gov/drugsatfda_docs/label/2014/20895s039s042lbl.pdf
7 Data on file.