The manufacturer of a unique prescription drug to treat the painful symptoms of inflammatory bowel diseases has halted production, forcing some patients to use steroids that can cause side effects.

Rowasa, a steroid-free anti-inflammatory suppository used by about 100,000 patients, disappeared from pharmacy shelves across the nation last month when Solvay Pharmaceuticals recalled the entire U.S. supply. The drug, officials said, was not breaking down fully in the body and could not be absorbed completely by patients. Solvay officials say they do not know when they might resume production.

Some patients use the drug episodically, but many others take it as a maintenance drug.

Despite the problems noted by the manufacturer, no patients are known to have been harmed by it. The major concern now is how patients will safely manage the debilitating flare-ups that characterize this group of chronic diseases. Steroids are effective but many patients dread the prospect of taking them for long periods because of their side effects, including weight gain, increased blood pressure and mood swings.

Patients whose inflammations go uncontrolled suffer severe fatigue, anemia and disabling digestive symptoms that can damage the intestines badly enough to heighten the risk of colon cancer or require major reconstructive surgery.

"We understand what our patients are going through," said Sharon M. Montgomery, who manages the product line for Solvay. "It is a very devastating disease, and when we cannot meet patients' needs, it's difficult for us, too. We're doing everything we can possibly do."

The chronic conditions for which the drug has been prescribed include Crohn's disease, ulcerative colitis and proctitis.

Washington area pharmacists have been checking with other drug retailers in a fruitless search for stocks of the drug for anxious patients. A pharmacy official at Giant Food said it is rare for a drug company to pull a prescription drug off the market indefinitely when there are no similar competing products.

Giant's 136 area drugstores have received no shipments since March, the official said. Solvay did not alert the government it was recalling the entire supply of Rowasa suppositories until May 18. Rowasa is available in another form, but it is not as effective as suppositories, doctors say.

It remains unclear whether faulty ingredients or inadequate packaging led to the failures, but until the Marietta, Ga., drug maker diagnoses the problem, it will not manufacture the product, Montgomery said.

Montgomery said the company is not withdrawing the drug permanently. "We're committed to the long-term manufacture of this product," she said. "We can't give you a date [for resumption], and that's very unfortunate, but we have to pinpoint the cause before we can move any further. It could be weeks or months. I get the phone calls, and we've gotten up to a couple hundred within a week."

Officials with the U.S. Food and Drug Administration said Solvay made the recall voluntarily and the government has little information about it. By the time Solvay notified the FDA, patients had used up most of the existing doses. Of the 600,000 boxes of the drug that were recalled, only 548 have been returned, Montgomery said.

"There is really no substitute for this," said Gary Roggin, a Bethesda gastroenterologist who advises the Washington area chapter of the Crohn's and Colitis Foundation of America. "Rowasa has become the therapy of choice for most people because it works as well [as] or better than steroids without side effects."

With no Rowasa suppositories available for patients who had depended on them, some doctors are prescribing steroids to ease inflammations.

Robynne Chutkan, a Georgetown University gastroenterologist, said steroids are acceptable only because nothing else is.

"Sometimes it's fine, but it's a steroid, and if you can heal things with Rowasa I prefer to do that," she said.