Cypress Bioscience Inc. said Wednesday its fourth-quarter loss narrowed, thanks to sales of its treatment for a medical disorder that causes pain in the muscles and connective tissue.

The San Diego company lost $5 million, or 13 cents per share, in the three months that ended Dec. 31, compared to a loss of $7.2 million, or 19 cents per share, in the final quarter of 2008.

Revenue jumped to $8.1 million from $949,000 in 2008.

Cypress said much of its revenue gain came from the launch of Savella, which is marketed by Forest Laboratories as a treatment for fibromyalgia. It received $2.1 million in royalty revenue and $4.6 million in sales force reimbursement tied to the drug.

Fibromyalgia has no known cause or cure.

The company's research and development expenses fell nearly 29 percent to $1.4 million in the quarter. But total operating expenses climbed 48 percent to $13.3 million from $9 million. The company also had a $1.1 million impairment charge tied to goodwill assigned to its personalized medicine services business.

For the full year, Cypress Bioscience lost $28.3 million on $27.3 million in revenue.