2 New Drugs Are Strongest to Combat Flu

Two drug companies have developed the most potent influenza drugs yet known--capable of easing the symptoms caused by all strains of the flu virus and shortening the duration of the most severe symptoms--fever, headache and muscle pains--by one-third to one-half, researchers will report in San Diego today.

Used prophylactically, one of the drugs has also been shown to be as much as 84% effective in preventing flu among people who have not been vaccinated against influenza.

Both drugs could be available for wide use by the 1999-2000 flu season, experts said Thursday. And unlike the now available, but minimally effective, influenza drugs amantadine and rimantadine, the new products apparently have little risk of adverse side effects.

The new drugs offer a way to prevent flu in cases in which a new strain suddenly appears and to treat it among people who have not been vaccinated.

The importance of drugs like these “is that, up until now, flu patients often left their doctor’s office with instructions for cough syrup, bed rest and fluids, typical treatments that merely mask the symptoms of influenza,” said Dr. John J. Treanor of the University of Rochester School of Medicine.

Now, he said, “we could see a change in this philosophy, where patients would come in very early and be treated with a pill that would actually treat the virus that causes the symptoms.”

The new drugs could have a major impact, said Michael King, a biomedical analyst with SG Securities, because “there isn’t anything on the market now that is effective.”

Researchers will present the first results from clinical trials with the drugs today at the Interscience Conference on Antimicrobial Agents and Chemotherapy. Relenza, developed by Glaxo Wellcome Inc., is inhaled through the mouth, and GS4104, developed by F. Hoffmann-La Roche and Gilead Sciences, is taken as a pill.

Each year in the United States, from 26 million to 55 million people contract influenza, and as many as 40,000--primarily the very young and the very old--die of it. The estimated annual cost of flu-related illness in this country is about $12 billion.

“Given the impact of influenza as a dramatic public health problem, [the new drugs have] the potential to be a significant medical advance for patients,” said John Garrison, chief executive officer of the American Lung Assn.

The primary method for protection against influenza is the flu vaccine. But scientists must guess a year in advance which strains of flu will predominate in the upcoming season so that a vaccine can be prepared.

That approach is not always successful. Last winter, for example, was a bad flu season because the major strain spreading through the population, called Sydney A, was not included in the vaccine.

Both of the drugs belong to a new class of agents called neuraminidase inhibitors.

When used as either a preventive or a treatment, they stop infected cells from releasing new viruses that can infect other cells, thereby slowing or halting the spread of the virus.

Treanor and Dr. Frederick G. Hayden of the University of Virginia Medical School in Charlottesville reported on two large studies of GS4104, one on 629 patients at 60 sites across the United States and one on 719 patients at 80 sites in Europe, Canada and China.

They found that the drug reduced the severity of symptoms, including fever and cough, by 40% in the U.S. trial and by 25% in the other study.

The duration of the symptoms was reduced 33% in the U.S. study. In the foreign trial, duration was reduced 30% if the drug was administered within 36 hours of developing symptoms and by 40% when given within 24 hours.

Results from the U.S. study also showed that GS4104 reduced secondary complications of influenza, such as bronchitis and sinusitis, by 50%.

Researchers studying the Glaxo drug are expected to report similar findings, but their results cannot be released to the media until this afternoon.

Although a 20% to 30% reduction in overall duration may seem small in a disease that normally lasts 10 days, it can make a major impact on how people feel, said Dr. Christopher Silagy of the Flinders Medical Centre in South Australia.

“The most debilitating symptoms of influenza occur in the first three to five days,” he said, “and the new drugs can knock up to two and a half days off that period.”

In other research, Dr. Arnold S. Monto of the University of Michigan School of Public Health will report on a large study of college students, employees and neighbors--most of them unvaccinated--who received Relenza as protection during last winter’s flu epidemic. Six percent of the people receiving a placebo developed flu, compared with only 2% of those receiving Relenza.

Like GS4104, Relenza showed “essentially no side effects,” Monto said. In fact, he added, more people taking the placebo reported side effects than those taking the active drug. The side effects reported were mostly flu-like symptoms.