ADELPHI, Md. - Government experts in the United States say prescription drugs like Vicodin and Percocet that combine a popular painkiller with stronger narcotics should be eliminated because of their role in deadly overdoses.

A U.S. Food and Drug Administration panel on Tuesday voted 20-17 that prescription drugs that combine acetaminophen with other painkilling ingredients should be pulled off the market.

The FDA has assembled a group of experts to vote on ways to reduce liver damage associated with acetaminophen, one of the most widely used drugs in the United States and Canada.

Despite years of educational campaigns and other federal actions, acetaminophen remains the leading cause of liver failure in the U.S., according to the FDA.

Panellists cited FDA data indicating 60 per cent of acetaminophen-related deaths are related to prescription products. Acetaminophen is also found in popular over-the-counter medications like Tylenol and Excedrin.

"We're here because there are inadvertent overdoses with this drug that are fatal and this is the one opportunity we have to do something that will have a big impact," said Dr. Judith Kramer of Duke University Medical Center.

But many panellists opposed a sweeping withdrawal of products that are so widely used to control severe, chronic pain.

"To make this shift without very clear understanding of the implications on the management of pain would be a huge mistake," said Dr. Robert Kerns of Yale University.

In a separate vote, the panel voted overwhelmingly, 36-1, that if the drugs stay on the market they should carry a black box warning, the most serious safety label available.

The FDA is not required to follow the advice of its panels, though it usually does.

A Health Canada representative is at the U.S. meeting and an analysis of comments received and information presented will be done over the summer, a Health Canada official said Tuesday.

Health Canada has developed a labelling standard for acetaminophen that includes a warning about liver toxicity, including specific information for people with serious kidney and liver disease and for alcohol users, Christelle Legault said Tuesday in an email.

"It is anticipated that the draft labelling standard for acetaminophen will be finalized by September 2009," she wrote.

In the U.S., prescription acetaminophen combination drugs were prescribed 200 million times last year, according to FDA data. Vicodin is marketed by Abbott Laboratories, while Percocet is marketed by Endo Pharmaceuticals. Both painkillers also are available in cheaper generic versions.

The FDA convened the two-day meeting to ask experts to discuss and vote on a slew of proposals to reduce overdoses with acetaminophen. The drug has been on the market for about 50 years and many patients find it easier on the stomach than ibuprofen and Aspirin, which can cause ulcers.

Earlier in the day, panellists took aim at safety problems with Tylenol and dozens of other over-the-counter painkillers. In a series of votes, the panel endorsed lowering the maximum dose of those products.

FDA's experts voted 21-16 to lower the current maximum daily dose of non-prescription acetaminophen, which is four grams, or eight pills of a medication like Extra Strength Tylenol.

The group was not asked to recommend an alternative maximum daily dose.

The panel also voted 24-13 to limit the maximum single dose of the drug to 650 milligrams. The current single dose of Johnson & Johnson's Extra Strength Tylenol is 1,000 milligrams, or two tablets.

In a third vote, a majority of panellists said the 1,000-milligram dose should only be available by prescription.

However, panellists rejected a proposal to pull certain cold and cough medicines off the market because of their role in overdosing.

The drugs in question, such as Procter & Gamble's NyQuil or Novartis' Theraflu, combine acetaminophen with other ingredients that treat cough and runny nose.

The FDA says patients often pair the cold medications with pure acetaminophen drugs, like Tylenol, exposing themselves to unsafe levels of the drug.

But panellists cited FDA data that said the medications play a minor role in acetaminophen overdoses, with only 10 per cent of acetaminophen-related deaths involving a cold and cough product.

"I don't think we should be advocating a solution to a problem that really is not there," said Dr. Osemwota Omoigui, of the Los Angeles pain clinic.

The panel voted 24-13 to keep the products on the market.