Shares of Progenics Pharmaceuticals Inc. closed Friday at $13.40 per share rising 25.94 percent, and climbed to $13.75 on after trading as its drug Relistor was approved in the U.S. by the Food and Drug Administration.

The drug was also approved in Canada in April 1 and reviewed positively by the European Medicines Agency's Committee for Medicinal Products for Human Use yesterday.

Progenics developed the drug partnering with Wyeth. Relistor is an injection to treat constipation caused by chronic opioid painkiller medications. The medicine is able to stop morphine-like drugs from interfering with bowel movements while allowing the drugs to continue blocking pain.

Relistor may have side effects such as abdominal pain, gas, nausea, dizziness and diarrhea, the Food and Drug Administration agency said.

Its price wasn't disclosed however the companies expect the product will be launched to the market in June. Wyeth will pay $15 million to Progenics as a result of the approval.

Citigroup analyst Yaron Werber upgraded Progenics stock to hold from sell and called the approval a pleasant surprise, Reuters noted.

The drug may generate $300 million in peak U.S. sales, George Farmer an analyst at Wachovia said according to Bloomberg.