Swiss drug group Hoffmann-La Roche has secured the US Food and Drug Administration (FDA) marketing approval for a prevention indication of the Tamiflu influenza antiviral drug for the disease which afflicts 40 million Americans every year.

Tamiflu (oseltamivir phosphate) was co-developed with Gilead Sciences and treats and helps prevent all common strains of the flu virus. It was already approved by the FDA in October 1999 for flu treatment in adults who already have symptoms.

Tamiflu will be available for flu prevention in adults and adolescents 13 years and older in the United States this influenza season.

Tamiflu is the first flu pill from a new class of drugs called neuraminidase inhibitors that are designed to be active against all common strains of the influenza virus. Influenza, or flu, is an acute respiratory infection caused by a variety of influenza viruses. Flu symptoms often include headache, chills and dry cough, which are followed rapidly by body aches and fever.

Each year, an average of about 1.5 lakh Americans are hospitalized and 10,000 to 40,000 people die from influenza and its complications. The use of current influenza treatments has been limited due to a lack of activity against all influenza strains, adverse side effects, and rapid development of viral resistance. Influenza costs the United States an annual $14.6 billion in physician visits, lost productivity and lost wages.

Neuraminidase inhibitors are designed to inhibit, or 'plug' the active site of an enzyme, called neuraminidase. Neuraminidase is found protruding from the surface of the two main types of influenza virus, type A and type B. It enables newly formed viral particles to travel from one cell to another in the body. By inactivating neuraminidase, viral replication is stopped, halting the influenza virus in its tracks.

In September 1996, Gilead and Hoffmann-La Roche entered into a collaborative agreement to develop and market therapies that treat and prevent viral influenza. In 1999, as Gilead's worldwide development and marketing partner, Roche led the final development of Tamiflu. Only 26 months after the first patient was dosed in clinical trials in April 1999, Roche and Gilead announced the submission of a New Drug Application to the FDA for the treatment of influenza.

Six months later in October 1999, Gilead and Roche announced that the FDA approved Tamiflu for the treatment of influenza A and B in adults. These accelerated efforts allowed Tamiflu to reach the U.S. market in time for the 1999-2000 flu season. In addition to the United States, Tamiflu is available in 26 countries worldwide.

Today, Roche continues to spearhead a label extension strategy, including additional Phase III treatment and prophylaxis studies. Prevention indication approval is still pending in a number of markets including Canada.