BioSante Pharmaceuticals ( BPA) is a sexy stock. The standout opportunity amidst the small drug company's well-stocked pipeline of hormone therapy products is a testosterone gel that, if approved for sale, would be used by menopausal women to boost their flagging sex drive. The commercial market for legitimate products to treat "female sexual dysfunction" barely exists today. This stands in stark contrast to the mountains of cash forked over by men for drugs like Viagra, Cialis and Levitra. But gender inequality over sexual dysfunction treatments is about to change, which puts BioSante in a sweet spot. And at a current stock price of $8.91 and a market cap of $164 million, the company is both underappreciated by investors and undervalued given the significant commercial potential for products like LibiGel. There are a bunch of reasons to like the BioSante story. For starters, there is well-established science behind LibiGel, and with that foundation comes a relatively lower risk that the product blows up. Doctors have long understood that a lower-than-normal level of the hormone testosterone contributes to a waning desire for sex in women, especially women nearing, or in, menopause. When testosterone levels are boosted back to normal levels, a woman's desire for sex also returns to more normal levels. Pfizer ( PFE) spent many years trying to prove that Viagra would also work for women, but while the drug did increase blood flow to the vagina (it does the same for a man's penis), the drug giant found that women who took Viagra did not have an increased desire for sex. This bolstered the belief that hormones play a larger role in female sex drive and forced Pfizer earlier this year to stop testing Viagra for women.