Adolor Corp., Exton, said today it narrowed its first-quarter loss to $13.2 million, or 29 cents a share, compared with a loss of $17.4 million, or 42 cents, in the same quarter last year.

The company said contract revenues for the three months ended March 31 were $1.8 million, compared to $2.6 million in the year-ago quarter, primarily due to a $700,000 decrease in revenue from GlaxoSmithKline after a co-promotion agreement for the drug Arixtra expired.

On April 9, Adolor and GlaxoSmithKline announced new safety issues with Entereg, a small molecule drug they're collaborating on that is intended to block constipation and other gastrointestinal side effects of opioid painkillers. Adolor's stock fell 59 percent after the study showed a higher risk of heart attacks, tumors and bone fractures in Entereg patients compared to placebo. The results could cause GlaxoSmithKline to drop Entereg development and its partnership with Adolor.

As of March 31, Adolor had $169.3 million in cash.

Shares were up 4 cents to $3.69 on the Nasdaq.