Ironwood Pharmaceuticals to cut 50 jobs

Ironwood Pharmaceuticals Inc., which won US approval to sell its first drug in 2012, said Wednesday that it will cut about 50 jobs, or about 10 percent of its workforce, in a move to refocus research and development on treatments for gastrointestinal conditions.

The biotechnology company, based in Cambridge, plans to complete the layoffs during the first quarter of this year, leaving it with about 480 full-time employees. It expects to take an accounting charge of $4 million to $4.5 million to cover severance costs.

Ironwood’s cutback will affect both research and general administrative employees, said company spokeswoman Trista Morrison. Exempted will be the sales force hired to market Linzess, the company’s approved drug to treat adults with irritable bowel syndrome and constipation, along with medical liaisons who educate doctors about the drug.

Sales of Linzess have been projected to top $1 billion annually within five years, but the treatment has been slow to take off. Ironwood reported $34.4 million in Linzess revenue for the third quarter of 2013 and $67.7 million for the nine months ended Sept. 30.

While company researchers have been focusing on a range of therapeutic areas, including respiratory and cardiovascular diseases, Ironwood executives have decided to concentrate more narrowly on the gastrointestinal field, Morrison said. She said the company will continue to seek to expand the market for Linzess while also developing treatments for other gastrointestinal disorders, such as dyspepsia, gastroparesis, gastroesophageal reflux disease, and lower abdominal pain.

“We’re really homing in on GI, because we feel like that’s where we have the experience, and that’s where we can bring the most to the table,” Morrison said.

Unlike other Massachusetts companies that have won Food and Drug Administration approval to sell potential blockbuster drugs, Ironwood has been conserving cash and thus far has not unveiled plans to build a new headquarters. Toward the end of 2012, the company signed a lease extension that added 93,000 square feet of space to its current offices near Kendall Square, bringing the total to about 300,000 square feet.