The start-up that made headlines four years ago for developing a nail polish that would detect date rape drugs is finally releasing a test kit for sale starting Thursday.

Undercover Colors scrapped the nail polish in favor of a gender-neutral small, disposable test to detect whether a drink has been doctored.

The tests, which use just a few drops of liquid, look and operate much like a pregnancy test. They can detect Xanax or its generic alprazolam, Valium (diazepam) and flunitrazepam, also known as Rohypnol, said CEO Barbara Cook. They do not screen for other common date rape drugs, such as GHB or ketamine.

Four classmates at North Carolina State University came up with the idea more than four years ago. The thinking was to give women a way to quickly and discreetly test their drinks at bars and parties with nail polish that changed colors when dipped into drinks laced with date rape drugs. It would take a few years for the science to catch up.

Date rape drugs are used in a fraction of all sexual assaults, but they still can put people in dangerous situations. They're tasteless and odorless, making them nearly impossible to detect and can make people drowsy or even cause them to black out.

The Undercover tests are small enough to carry in a purse or wallet and can be purchased online for $34.99 for a five-test starter kit or $49.99 for 10 tests.

It takes about a minute to process and looks like a quarter-sized medallion with a foil coating on one side that resembles a miniature pregnancy test when peeled back. Women can either drop the liquid on the test or dunk it into a drink. The readout displays one dark pink line if the drink is bad or two lines if it's OK.

"We're focused mostly on getting product out there, and we want to hear the first story of how this helps someone because that will make it all worth it," said Undercover Colors' director of research and development, Nick Letourneau, adding that it could eventually display a pattern or a written word like newer pregnancy tests do.

Letourneau said scientists got the nail polish technology to a point where it was working, but executives decided to shelve it in favor of something that could be used more easily by both men and women. Their market research showed surprising demand from men, and not just in the LGBTQ community, he said.

"The technology works," Cook said. "The form in which that technology was to be delivered is the thing that has evolved over time and to get it it into a form that helps most people in the best way is to begin with is here."

They also created a stick-on nail, but it isn't available for public sale yet.

Undercover Colors is timing the release as college students head back to school. The first semester can be a dangerous time. More than half of college sexual assaults occur between August and December, and freshmen are attacked almost twice as much as other undergraduates, according to the Department of Justice. The agency analyzed sexual assaults of female college students from 2014 to 2015, the most recent data available.

"One of the reasons it's one of the most underreported crime in the freshman year is because women think it's their fault. And that's a huge problem," Cook said.

Private investors, including Mike Hockenberry, Marjorie Kaufman, Liz Pharo and Mark Cuban, have backed Undercover Colors, Cook said. The start-up has not received any institutional investor or venture capital funds.