The U.S. Food and Drug Administration expert panel on drugs for children reviewed nine new adverse event reports in kids taking the inhaled treatment, including five deaths over a period of about a year, among other studies finding increased hospitalization and asthma-related death in kids.

"The data is very troubling because both the increase in hospitalization and in mortality is so different" from what doctors currently believe, said Thomas Newman, an epidemiologist at the University of California, San Francisco, and panel member.

Serevent's use has fallen dramatically since original reports of asthma deaths came to light a few years back. But it is one ingredient in Glaxo's blockbuster asthma drug Advair, and the new worries could impact that drug, which had $6.8 billion in 2006 global sales.

At least two panel members said the data was so convincing that Serevent should be pulled from the market. The FDA said it will consider the safety of all drugs in the class, called long-acting beta agonists, at a future meeting.

"The members of this committee think this is an urgent public health issue," panel chairwoman Dr. Marsha Rappley, a neurology and psychiatry expert at Michigan State University, said.

Novartis also sells a long-acting beta agonist called Foradil.

FDA staffers said no date for the meeting has been set.