KANSAS CITY, KAN. ? Dr. Richard McCallum has felt somewhat helpless.

Over the past 25 years, he’s seen how irritable bowel syndrome can change a patient’s life. But he’s never been able to prescribe medication for his patients.

That will change next month, when the drug Zelnorm goes on the market. The Food and Drug Administration gave approval to the drug last week.

“It’ll be a huge boon to patients who were not in the past having their needs met,” McCallum said.

McCallum, professor and chief of the gastrointestinal department at the Kansas University Medical Center, led a 10-patient clinical trial of Zelnorm the past two years. It was part of a nationwide, 2,965-patient trial.

McCallum also served on an FDA panel that studied the drug’s side effects, which delayed its release for a year and had one consumer advocacy group saying the FDA never should have approved Zelnorm’s use.

Irritable bowel syndrome affects between 10 percent and 20 percent of the population, mostly women. It causes abdominal pain and severe diarrhea, constipation or both.

Zelnorm, marketed by Novartis, is far from a cure. Patients in the clinical tests fared only 5 percent to 11 percent better taking it rather than taking dummy pills.

But McCallum said he expected doctors to use it when traditional treatments  such as laxatives, stress management and diet changes  didn’t work.

“It wasn’t day and night, but you’ve got to realize irritable bowel syndrome is a chronic, lifelong condition,” he said. “It’s a quality-of-life change.”

The FDA abruptly halted approval for Zelnorm last year, citing concern about an increase in gall bladder and other abdominal operations among patients testing the drug. Last week, the FDA said the extra surgeries appeared to be a coincidence.

To be certain, the FDA ordered Novartis to study how patients fare as sales begin, and to closely monitor any reports of side effects.

But the consumer advocacy group Public Citizen chastised the FDA’s handling of the approval process.

“It’s another serious, reckless mistake for the FDA,” said Dr. Sidney Wolfe, who works for Public Citizen.

Wolfe said Zelnorm might worsen ovarian cysts, a claim the FDA said it couldn’t prove or disprove.

McCallum said he was convinced the drug was safe and the extra study by the FDA should prove its safety.

The drug is due out in August, the same month KU Med is launching a new gastrointestinal clinic for women. McCallum said it was a booming field for medicine.

“We now have a major advancement in treatment,” he said. “It opens the door for patients who have been reluctant or unhappy with medical treatment.”