UK-447841 is a neprilysin inhibitor (NEPI) which was under development for the treatment of female sexual dysfunction. It is taken as-needed orally. The drug is intended to work by inhibiting vasoactive intestinal peptide (VIP) hydrolysis by neprilysin (NEP). However, neprilysin is also involved in the metabolism of more than 50other hormones and neuropeptides, for instance oxytocin among others. UK-447841 was under development by Pfizer. It reached phase 2 clinical trials prior to the discontinuation of its development in 2008.