An experimental once-a-day pill offered relief to nearly half the people with severe, long-term constipation, researchers reported on Wednesday.
The drug prucalopride, which Belgium-based Movetis NV plans to market in Europe under the brand name Resolor, could help many of the 11 million people in Europe and 25 million worldwide suffering from chronic constipation.
And a second study showed an injection can help people with constipation caused by painkillers used mainly in cancer patients.
Chronic constipation affects 15 percent of the U.S. population — as many as 50 percent of the elderly.
Dr. Michael Camilleri of the Mayo Clinic in Rochester, Minnesota, and colleagues tested 620 volunteers who had fewer than two spontaneous bowel movements per week. For some, it was as little as twice a month.
Prucalopride helped — 46 percent of the patients who took either of two doses of the drug were able to go one time a week more, on average, compared to 26 percent of patients getting placebo.
"However, there is concern about a potential cardiac risk associated with this constipation-reducing drug," Arthur Moss of the University of Rochester School of Medicine & Dentistry in New York wrote in a commentary in the New England Journal of Medicine.
Moss said it is similar to other constipation drugs that were pulled from the market because of warnings about heart-related problems. However, the new drug has undergone further testing to assess cardiac risk, its maker said.
"This medication is far safer," Camilleri said in a telephone interview. He said his team spent nine years looking for heart concerns in patients.
"(Prucalopride) is much more specific at the doses needed to affect the GI (gastrointestinal) tract."
The most common side effects were headache and abdominal pain. "All in all, prucalopride could be a useful constipation-reducing medication in the short term," said Moss.
The study was designed by Johnson & Johnson, which still has rights to the drug outside Europe. Movetis on its web site says it hopes to launch the drug in 2010.
Camilleri said the drug works very differently from laxatives, which add fiber and fluid to distend the colon and prompt it to expel its contents.
Constipation is a serious side effect of opioid painkillers used in cancer and heart patients, and a separate study in Thursday's Journal says the newly approved injectable drug methylnaltrexone relieved the problem in 48 percent of 63 volunteers who received one dose.
The drug, sold under the brand name Relistor by Progenics Pharmaceuticals and Wyeth, did not reduce the effectiveness of the painkillers.
"In advanced illness, opioid-induced constipation can rival distress caused by pain," said the team led by Jay Thomas of San Diego Hospice and Palliative Care.
The drug was approved by the U.S. Food and Drug Administration last month. Tests of the Relistor to treat opioid-related bowel problems after abdominal surgery have produced disappointing results.