​BioCryst Pharmaceuticals stock fell 8 percent in Monday morning trading after it reported fourth-quarter earnings that beat estimates but also reported results for an experimental drug that disappointed investors..

The net loss for the quarter was $4.5 million, or 6 cents per share, down significantly from $18.1 million, or negative 25 cents per share from the same period in 2015, according to a filing with the Securities and Exchange Commission.

Ten analyst expectations averaged an estimate net loss of 23 cents for the quarter.

BioCryst Pharmaceuticals is a drug development company that designs drugs to block key enzymes involved in rare diseases.

Fourth quarter revenues increased to $9 million, up from $4.6 million in fourth quarter 2015. The company attributes the high increase in revenues to Seqirus and higher peramivir royalty revenue.

BioCryst stock opened Monday at $4.20, down almost 20 percent from Friday’s close of $5.49. It was trading at $5.50, down 44 cents, or 8.1 percent, in late Monday morning trading.

Research and development expenses decreased in the fourth quarter to $12.2 million, down from $19 million in the 2015 fourth quarter due to lower spending on drugs associated with a discontinuation of avoralstat development.

For 2017, BioCryst expects net operating cash in the range of $30 million to $50 million and operating expenses to range from $53 million to $73 million.

BioCryst filed Monday results from an interim trial analysis of its APeX-1 clinical trial of BCX7353 for the treatment of HAE attacks. The report cited “statistically significant and clinically meaningful reductions in attack frequency,” which was down 63 percent in overall attack rates.

“We are extremely excited to have such a strong treatment effect in reducing HAE attacks with our once daily oral therapy,” said CEO and President Jon Stonehouse. “What is even more encouraging is the dramatic benefit seen in the reduction of peripheral attacks and mixed peripheral and abdominal attacks.  A once daily oral therapy with an 88% reduction in these attacks has the potential to make a huge difference in HAE patients’ lives.”

Recently, the company has also announced that the European Medicines Agency accepted the company’s filing of its peramivir Marketing Authorization Application for treatments of symptoms typical of influenza in adults. This starts a review process by the agency for all of the European Union member states.

BioCryst has also seen recent success when Health Canada approved of its RAPIVAB for treatment of the flu in mild situations. The drug is being commercialized by Seqirus around the world.

Note: This story is from the North Carolina Business News Wire, a service of UNC-Chapel Hill’s School of Media and Journalism