Exploration of therapeutic targets for sexual dysfunctions: lessons learned from the failed stories

Introduction: The ratio between research and successful targets in a disease class gives a good indication about the extent of the exploration of additional targets for diseases in that class. This ratio is still very low for the field of sexual medicine. 'Failures' in drug development can be highly instructive, but are not often addressed. Areas covered: We performed a review of the literature based on published data on four failure stories including targeting adrenergic receptors for erectile dysfunction (ED), targeting dopamine receptors by apomorphine for ED, serotonergic transporters as a target for premature ejaculation and PDE5 as a target for female sexual dysfunctions. The search included: i) a MEDLINE search from 1966 through November 2010 limited to English language medical literature, ii) relevant abstracts from 2009 and 2010 and iii) a pipeline search for therapeutics in development. The aim is to inform readers about the lessons learned from four selected failed therapeutic stories during therapeutic target exploration for sexual dysfunctions. Expert opinion: By learning from failures, a drug may not only be kept alive, but also better therapeutic strategies and design of new drugs may be developed.