Bremelanotide and flibanserin for low sexual desire in women: the fallacy of regulatory precedent

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.