Bremelanotide and flibanserin for low sexual desire in women: the fallacy of regulatory precedent.
This paper critically examines the regulatory approval of two FDA-approved drugs for hypoactive sexual desire disorder (HSDD) in women: flibanserin (Addyi, approved 2015) and bremelanotide (Vyleesi, approved 2019). The authors analyze the clinical trial data and outcome measures underpinning each approval. They report that clinical trials for flibanserin showed an average of only approximately one additional enjoyable sexual experience every two months compared to placebo, while bremelanotide trials showed no such numerical gain. The paper also highlights concerns about shifts in primary outcome measures during trials, a contested diagnostic indication, and the influence of a politicized, industry-sponsored patient advocacy campaign on flibanserin's approval—which succeeded on its third regulatory attempt. The authors argue that bremelanotide's approval, despite even weaker efficacy evidence, was facilitated by the regulatory precedent set by flibanserin. The paper calls for reconsideration of these approvals and recommends reforms to better manage conflicts of interest and define clinically meaningful benefit in future regulatory decisions. A key limitation is that this is an opinion/review piece rather than an original clinical study, and does not present new primary data.
Why this grade: This is a critical review/opinion paper that synthesizes existing clinical trial data and regulatory history rather than generating new primary evidence; it does not itself constitute a controlled study or meta-analysis.
The US Food and Drug Administration (FDA) has approved two drugs for 'hypoactive sexual desire disorder' in women, flibanserin (Addyi) in 2015 and bremelanotide (Vyleesi) in 2019. In this paper we examine the outcome measures and clinical trial data upon which regulatory approval was based. In clinical trials, flibanserin led to an average of only one additional enjoyable sexual experience every two months, bremelanotide to none. Trials for both drugs feature shifts in primary outcomes and a contested indication. A politicised industry-sponsored advocacy campaign and conflicted patient and expert testimony likely influenced flibanserin's approval at its third attempt. Bremelanotide, with even weaker efficacy, capitalised on the regulatory precedent set by the approval of flibanserin. Reconsideration of regulatory decisions to approve these drugs is in order, as well as a broader examination of how future regulatory decisions can better address conflicts of interest and clinically meaningful benefit.
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