The Food and Drug Administration said yesterday that three popular asthma medicines may increase risks of hospitalization and death in some asthma patients.

The safety of the drugs - Serevent, manufactured by GlaxoSmithKline P.L.C.; Symbicort, made by AstraZeneca P.L.C.; and Foradil, from Novartis AG - will be reviewed by outside medical advisers to the FDA at a two-day hearing next week in Rockville, Md.

While three of the medications, known as long-acting beta agonists, or LABAs, had a "positive risk difference" in clinical studies, it was only "statistically significant" for Serevent, FDA staff said, in briefing materials posted yesterday on the agency's Web site.

A fourth drug, Advair made by GlaxoSmithKline, had no increased risk of respiratory complications, FDA staff said. Advair has about $4 billion in annual sales and is Glaxo's biggest product.

Medical experts will consider the potential risks of all LABAs, including Advair, at the two-day hearing Wednesday and Thursday, will hear presentations by the drugmakers, and will make recommendations. The drugs already carry strong warnings, but the findings next week could lead to more specific instructions for patients.

Children ages 4 to 11 taking LABA drugs appeared to be at greatest risk for complications than those taking older treatments, FDA staff said. African Americans showed elevated risk compared with other groups, and females had higher risks than males.

In clinical studies, there were 20 asthma-related deaths - 16 in patients treated with LABA drugs, and four among patients taking other non-LABA medications. "All the asthma-related deaths were among Serevent-treated subjects," the FDA said.

Separately, the FDA is investigating a possible link between Singulair, Merck & Co. Inc.'s popular allergy and asthma drug, and suicide.

In March, the FDA said it was reviewing Singulair for potential safety issues after receiving a handful of reports of mood changes, suicidal behavior and suicide in patients who had taken the drug.

The FDA review of Merck's biggest product, with $4.3 billion in annual sales, is likely to wrap up in the next month or two, Timothy Anderson, analyst at Sanford C. Bernstein & Co. L.L.C., said in a research note yesterday.

"Investors need to be mindful of these ongoing safety reviews by FDA and their potential commercial implication," he wrote.

Merck updated Singulair's labeling four times in the last year to include information on a range of reported side effects: tremors, anxiousness, depression and suicidal behavior.

The FDA is notifying the public earlier about possible safety issues. The policy change came after the agency was criticized for acting too slowly on information about the risks of Merck's pain reliever Vioxx and GlaxoSmithKline's diabetes pill Avandia.