Female sexual health company Sprout Pharmaceuticals, which is seeking to develop a drug called a female equivalent of Viagra has raised $17.5 million in a round that could reach $20 million.

The fundraiser follows a $5 million haul that the company raised in April.

A total of 55 investors participated in the latest equity offering, which launched June 15, according to securities filings.

Sprout said in the filing that proceeds from the offering will be used for working capital purposes.

Sprout, formed in late 2011, is working to develop and commercialize a compound it acquired from German pharmaceutical company Boehringer Ingelheim. Boehringer Ingelheim had studied the compound flibanserin as a possible treatment for hypoactive sexual disorder, which is more simply described as diminished sexual desire.

Currently there are no U.S. Food and Drug Administration approved products to treat hypoactive sexual disorder.

Boehringer Ingelheim took flibanserin through clinical trials and had filed a new drug application with the FDA. The company planned to market the drug under the name “Girosa.” But in 2010, an advisory committee to the FDA declined to recommend approval for the drug candidate and instead said the company needed to provide more data about the compound’s efficacy and safety.

The FDA later issued a complete response letter, declining approval for the compound. Shortly afterward, Boehringer Ingelheim abandoned its efforts to pursue U.S. regulatory approval for flibanserin.

Privately-held Sprout is led by Bob Whitehead, former CEO of male sexual health company Slate Pharmaceuticals.

Slate, which was also based in Raleigh, developed and commercialized testosterone product Testopel. Testopel is a pellet implanted just below the skin to deliver testosterone to men who have low levels of the hormone.

Slate was sold late last year, according to Sprout’s website.