Shares in pharmaceutical small cap Furiex Pharmaceuticals (FURX) took off more than 140 percent on Monday following news that their experimental drug for treating irritable-bowel syndrome (IBS), eluxadoline, has met clinical targets for stool consistency and reduction of abdominal pain set with U.S. and European regulatory bodies in two large phase-III studies.

A Huge Bounce for FURX

Shares were up over 165.8 percent immediately after markets opened, jumping from just under $46 a share to nearly $122 at their peak. While shares retreated to just over $100 a share by late morning, they charged back around lunch and maintained a price over $110 a share.

This movement also came on extremely heavy volume, with shares moved on the day approaching 5 million despite an average daily volume of under 100,000 shares a day. All told, the market cap for Furiex spiked from just over $475 million to over $1.15 billion overnight.

A New Entry into a Large Market

Much of the optimism regarding Furiex comes from the size of the market for potential IBS treatments. Approximately 28 million patients in the United States and Europe suffer from the chronic disease that can lead to severe diarrhea.

“By our math, it looks like a pretty doggone good market,” Chairman Fred Eshelman said on a call with investors, observing that there was only one other IBS drug currently on the market. He estimated that annual sales for the drug should be in the $750 million to $1 billion range.

Large Trials Show Eluxadoline Beating Placebo at Multiple Doses, Trial Lengths

The double-blind studies, which enrolled almost 2,500 IBS patients, compared results to placebo and showed positive results for 75-mg and 100-mg doses.

While the FDA called for results after 12 weeks of treatment, European regulators were looking for a 26-week study. And eluxadoline satisfied both, with patients showing improvement over the placebo at both 12 and 26 weeks.