WASHINGTON (Reuters) - U.S. health officials on Monday warned consumers to stop taking decongestants and diet drugs that contain a key ingredient linked to ``very rare'' cases of strokes while regulators moved to take it off the market.

The ingredient, phenylpropanolamine (PPA), is found in dozens of over-the-counter products, including cold medicine Dimetapp and weight-loss drugs, such as Dexatrim and Acutrim. PPA works as a decongestant in cough and cold remedies and an appetite suppressant in diet drugs.

The Food and Drug Administration (news - web sites) (FDA) said it has asked all drug companies voluntarily to stop marketing products containing PPA. Makers would have the option to reformulate the products with other ingredients.

The agency also is writing a proposal that will make the sale of PPA products, both prescription and over-the-counter, illegal. Finalizing a ban is likely to take several months, the FDA said.

Two manufacturers said they would stop making PPA-containing products, and one drug store chain said it would no longer sell PPA medicines.

Other companies were reviewing the FDA announcement, according to the Consumer Healthcare Products Association (CHPA), which represents makers of nonprescription drugs.

The group's members ``continue to stand by the safety of PPA-containing products when used according to label directions,'' CHPA senior vice president William Soller said, but he added that companies ``acknowledge FDA's action.''

Strokes In Young People

After reviewing a Yale University study, regulators determined that PPA seemed tied to very rare'' cases of bleeding strokes in adults under age 50, particularly women, said Dr. Charles Ganley, head of the FDA's division of over-the-counter drugs.

We do believe there is some association between (PPA) and the risk for this event,'' Ganley said in an interview.

We don't want to be alarmist. It is a very rare occurrence, but when you develop it, it could be devastating,'' causing disability or death, he added.

The PPA warning comes amid an FDA review of another widely used nonprescription weight-loss ingredient, the herb ephedra. For years, the agency has been worried that ephedra may be linked to heart attacks, seizures and deaths. Makers insist ephedra products are safe when used as directed.

With PPA, Ganley said it was hard to determine how much the ingredient might elevate stroke risk. At an advisory committee meeting last month, FDA officials estimated PPA might cause between 200 and 500 hemorrhagic strokes per year in patients age 18 to 49. U.S. consumers bought about 6 billion doses of PPA last year.

In the study, hemorrhagic strokes, or bleeding into the brain, occurred within three days after people took PPA products.

You could not predict who it would occur in,'' Ganley said, adding that men as well as women could be at risk.

The FDA panel recommended that PPA should no longer be ''generally recognized as safe,'' a requirement for over-the-counter drugs.

CHPA has disputed the Yale study as inconclusive. The group had funded the research to address long-standing FDA concerns about PPA's safety.

The New England Journal of Medicine (news - web sites), however, is planning to publish findings from the Yale study in its Dec. 21 issue. On Monday, the journal posted the article, as well as a study on ephedra's risks, on its Web site, citing the ``potential public health implications.''

Some Products Discontinued

Drug maker SmithKline Beecham Plc (SB.L) said it was stopping production and shipment of Contac 12-hour cold capsules, the only formulation of Contac that contains PPA, and had asked retailers to stop selling it.

Bristol-Myers Squibb Co. (NYSE:BMY - news) said it would stop marketing its PPA products, Comtrex Flu Therapy and Fever Relief, Comtrex Deep Chest Cold and cold remedy Naldecon.

Meanwhile, Walgreen Co. (NYSE:WAG - news) the nation's largest drugstore chain, was directing stores to pull PPA products from shelves.

Other products that contain PPA include some versions of Alka-Seltzer Plus, Coricidin, Tavist-D and Triaminic.

Some companies already have substituted pseudoephedrine, another approved nonprescription ingredient, for PPA in their cold products.

For over-the-counter diet aids, the FDA has not cleared any alternative, active drug ingredients. Manufacturers would have to switch those products to natural ingredients, which maker Chattem Inc. (NasdaqNM:CHTT - news) has done with its Dexatrim Natural.

Eight prescription-only decongestants contain PPA. Companies would need to receive FDA approval to market revised formulas of those products.

(From Reuters)