U.S. health regulators know that once a new drug hits the market, their system to monitor potential side effects is limited and they are seeking advice to fix it following a string of drug recalls and other safety concerns.

Some doctors, consumer advocates and others said the Food and Drug Administration’s safety net fails to catch meaningful data soon enough. Others said the system works - it just needs more people to report potential problems to the agency.

The Adverse Event Reporting System, or AERS, collects voluntary reports of possible reactions from physicians, pharmacists and patients. Drug companies must report problems.

On Wednesday, the FDA will begin a two-day meeting with a panel of outside advisers to evaluate and discuss possible improvements for the system, often referred to as MedWatch.

The meeting comes after two painkillers - Merck & Co. Inc.‘s Vioxx and Pfizer Inc.‘s Bextra - were pulled from the market over possible heart risks in the last eight months. The withdrawals raised concerns over the FDA’s handling of drug safety and followed earlier worries over whether antidepressants raise the risk of suicide in youth.

Top FDA officials acknowledge that, while AERS can effectively detect problems, the system is flawed.

In a recent letter to the panelists before the meeting, Paul Seligman, head of the FDA’s statistical science office, said reports “are not systematically collected” and “are often missing important clinical information.”

He said they can also be tough to evaluate if the patient had been taking other drugs or if the media had drawn attention to a certain problem, which can cause a flood of reports.

Last year the FDA said it received about 400,000 reports and about three-fourths were related to drugs. In 2003, there were about 250,000 reports.

About 40 percent are submitted online while the remaining 60 percent are split between mailed and faxed paper forms, the FDA said. Less than 1 percent are done by phone.

Anne Trontell, deputy director for FDA’s drug safety office, said reports are entered separately into the agency’s database and staff often must call doctors for more details.

Experts have estimated as few as 10 percent of potential side effects are reported. Several doctors said time pressures make it tough to download forms or use the MedWatch Web site.

“Getting physicians to do things is like herding cats,” University of Washington epidemiologist Bruce Psaty said.

Public Citizen’s Sidney Wolfe said the reports are helpful - there just needs to be more, so trends show up sooner. Even then the FDA, which has taken as long as two to three years to act on a signal, needs to move faster, he said.

“It would work even better if you put more volume in it,” said Wolfe, who heads the consumer organization’s Health Research Group. The agency could offer financial incentives, even if only for select groups, he said.

FDA’s Trontell said the number of reports would make it “challenging” to offer payments. “It’s been growing steadily.”

Recently, FDA officials began to scour third-party databases for possible patterns, analyzing information from insurance companies and commercial vendors.

“It’s exciting to look at the data. The challenge will be to integrate it and make good sense out of it,” Trontell said, adding the meeting will help judge how well data mining works.

Psaty said the FDA should expand its use of outside databases, rather than focus on sporadic reporting. “I would not spend a lot of additional money or effort trying to fix MedWatch,” he said.

Still, FDA officials are working on an updated, easier-to-use, Web-based reporting system called AERS II that would send many reports directly into the FDA’s database.