Japan Approves Inavir (laninamivir) for Flu

Japan approves second new flu antiviral this year

Robert Roos * News Editor

Sep 10, 2010 (CIDRAP News) – Japan today approved a new long-acting influenza antiviral drug, Inavir (laninamivir), made by Daiichi Sankyo Co. Ltd., marking the second new flu drug licensed there this year.

In announcing the approval, Daiichi said one dose of laninamvir, which is inhaled, has been shown to be as effective as 5 days of treatment with oral oseltamivir (Tamiflu), the most widely used flu drug. Laninamivir is a neuraminidase inhibitor, like oseltamivir and zanamivir (Relenza), which have been in use for about 10 years.

Laninamivir is administered with an inhaling device, like zanamivir. Daiichi said it is effective against influenza A and B viruses.

In January Japan approved another new neuraminidase inhibitor, peramivir, which is given intravenously, a route that permits its use in critically ill patients who might not be able to take oseltamivir or zanamivir. Peramivir, known in Japan as Rapiacta, is sold there by Shionogi & Co. Ltd. under an agreement with BioCryst Pharmaceuticals of Birmingham, Ala.

Neither peramivir nor laninamivir has been approved in the United States. Peramivir, however, is being tested in two US phase 3 clinical studies, and it was given to a limited number of patients during the H1N1 pandemic after the Food and Drug Administration issued an emergency use authorization (EUA) in October 2009.

Laninamivir, formerly known as CS-8958, was developed by Daiichi Sankyo but is co-owned by Biota Holdings, based in Melbourne, Australia, according to company reports. A Dow Jones news report published today said the Japanese firm has not completed its overseas development plan for the drug.

The results of a laninamivir trial in children under the age of 10 were published in Antimicrobial Agents and Chemotherapy in April. About 180 children who had flu symptoms for 36 hours or less were randomly assigned to receive either oseltamivir or one 20-mg or 40-mg dose of laninamivir.

For patients who had influenza A/H3N2 or influenza B, there were no significant differences in recovery time between the laninamivir and oseltamivir groups, according to the report. But laninamivir shortened the recovery time by more than 2 days for patients who had oseltamivir-resistant H1N1 infections (seasonal H1N1 viruses were widely resistant to oseltamivir in the 2008-09 flu season).

In August 2009, Biota reported that laninamivir compared well with oseltamivir in a phase 3 trial in adults. The trial, conduced by Daiichi in Japan, Korea, Taiwan, and Hong Kong, showed that a single dose of the new antiviral was as effective as oseltamivir given twice a day for 5 days, the company said.

The use of antivirals, especially oseltamivir, to treat seasonal flu patients has been described as much more common in Japan than in the United States and most other countries. In recent years there have been some reports, mainly from Japan, about confusion and self-injury in adolescents being treated with neuraminidase inhibitors.

The reports led the FDA's Pediatric Advisory Committee in 2007 to recommend stronger label warnings for oseltamivir and zanamivir, though the panel said it was unclear if the two drugs played any role in the reported adverse events.