If sexual statistics are to be believed, roughly 43 percent of American women suffer from some form of female sexual dysfunction. But pharmaceutical companies to date have only commercialized male sex drugs. Pfizer’s (NYSE: PFE) Viagra in 1998 famously became the first erectile dysfunction drug targeting men looking to revive their sex lives. It spurred other firms to develop libido-enhancing drugs for a market that now tops $5 billion a year. Meanwhile women are still waiting for just one drug that could become a “female Viagra.”