FDA Approves Use of Experimental Antiviral For H1N1 Flu

By JENNIFER CORBETT DOOREN

WASHINGTON -- The U.S. Food and Drug Administration is allowing the use of an experimental antiviral drug to treat severe cases of H1N1 or swine flu.

The drug, peramivir, is currently being developed by BioCryst Pharmaceuticals Inc. and is undergoing testing required for regular FDA approval.

The FDA issued a so-called emergency use authorization late Friday that allows doctors to use peramivir, which is delivered intravenously, in certain hospitalized adult and pediatric patients with confirmed or suspected H1N1 influenza.

A handful of doctors have already treated patients with severe cases of H1N1 using peramivir obtained through the agency's expanded access rules that allow individual patients to obtain experimental drugs if certain conditions are met. The emergency-use authorization allows use of the drug without prior FDA approval.

The FDA said there's only limited clinical data about whether peramivir is safe and effective, but "based upon the totality of scientific evidence available, it is reasonable to believe that peramivir IV may be effective in certain patients."

The company said it is completing production of approximately 130,000 courses of peramivir and is prepared to make more, if required.

The FDA said peramivir should only be used in patients who have not responded to or can't take the oral antiviral drug Tamiflu, made by Roche or Relenza, which is an inhaled drug made by GlaxoSmithKline PLC. Like Tamiflu and Relenza, Peramivir works by inhibiting neuraminidase, an enzyme that's involved with the spread of the influenza virus within the body.

The federal Centers for Disease Control and Prevention asked the FDA to grant peramivir emergency use to help cope with the influenza pandemic which has killed more than 1,000 people in the U.S. since April and hospitalized thousands more. The CDC will control and track distribution of peramivir to hospitals.

As of Oct. 17, 46 states were reporting "widespread" influenza activity and many doctors offices have been swamped with swine-flu patients. The CDC said more than 7% of outpatients visits in the week that ended Oct. 17 were attributed to influenza-like illnesses -- a rate higher than during the peak of the last few seasonal influenza seasons. The CDC said "many millions" of Americans have been sickened with H1N1 influenza since the virus was first discovered in April.

The U.S. government has ordered enough vaccine to make up to 251 million doses if needed, but production has been slower than originally anticipated.

A total of 11.3 million doses of vaccine had been shipped to U.S. doctors, hospitals, and clinics as of Wednesday, according to the CDC, out of a total of 14.1 million doses that manufacturers had shipped to warehouses by that time. By Friday, 16.1 million doses of vaccine had been shipped to warehouses, the CDC said.

The total is far below the government's most recent estimate that by the end of this month, about 28 million to 30 million doses would be shipped to warehouses for further distribution. That estimate itself is a revision, made last week, from a prior expectation of about 40 million doses by the end of the month. In July, the government had predicted that about 100 million doses would be ready in October.

Write to Jennifer Corbett Dooren at jennifer.corbett-dooren@dowjones.com