Pozen Inc. reported a wider first-quarter loss Thursday on a mix of lower revenues, higher costs, and difficult comparisons to the year before, when the drug developer benefited from a huge payment for an arthritis drug.

The company lost $5.7 million, or 19 cents per share, compared with a loss of $3 million, or 10 cents per share, during the same period a year prior.

Revenue fell 36 percent to $4.5 million from $6.9 million.

During the prior year period, the company had a $3.1 million payment from AstraZeneca, the company's partner on the arthritis drug Vimovo. The bulk of the company's current revenue came from sales of the migraine drug Treximet.

Analysts polled by FactSet expected a loss of 23 cents per share on $4.6 million in revenue.

Meanwhile, operating expenses rose 3 percent to $10.2 million.

Shares of Pozen rose 7 cents to $6 in afternoon trading.