Barbara Boughton

September 18, 2009

September 18, 2009 (San Francisco, California) — A phase 3 randomized double-blind trial of oral oseltamivir and peramivir has confirmed the efficacy and safety of the experimental intravenous (IV) drug peramivir for the treatment of seasonal influenza.

Unlike oseltamivir, peramivir is usually administered in a 1-time dose, and might be especially ideal for patients with severe influenza, according to researchers here at the 49th Interscience Conference on Antimicrobial Agents and Chemotherapy.

"We were successful in confirming the efficacy and safety of peramivir seen in the phase 2 study," said lead researcher Shigeru Kohno, MD, from Nagasaki University in Japan, in an interview with Medscape Infectious Diseases. "Peramivir is truly a potent drug for influenza treatment."

In the study of 1091 patients, subjects with a positive influenza rapid-antigen test were randomized to peramivir, either 300 mg or 600 mg, administered once intravenously or to oral oseltamivir 75 mg administered twice daily for 5 days.

Recovery in all 3 groups was similar. Time to alleviation of symptoms was 78 hours for the 300 mg dose of peramivir, 81 hours for the 600 mg dose, and 81.8 hours for oseltamivir. The incidence of adverse drug reactions was significantly lower with peramivir 300 mg than with oral oseltamivir (P = .0382).

The study was designed to show noninferiority to oseltamivir and, in that sense, it succeeded, Dr. Kohno said.

"Results from the phase 3 study demonstrate that peramivir has potential for immediate relief from influenza, with a better safety profile than oseltamivir," Dr. Kohno said. He noted that an unpublished study on high-risk influenza patients has shown peramivir's potential for alleviating symptoms. In this study, patients received peramivir once daily for up to 5 days, and results indicated that multiple doses of the drug led to even greater resolution of symptoms than the single dose in patients with severe disease, Dr. Kohno said, adding that "it would be a great option for patients who may experience aggravation of symptoms during influenza infection."

"Peramivir is appropriate for all patients in need of influenza treatment. And the fact that peramivir is appropriate for a wide range of patients makes it possible for it to be recommended as a first-line therapy. It's a promising new drug for various types of influenza," Dr. Kohno said.

"This was the first randomized clinical study of the efficacy of IV peramivir during an influenza season, and it showed the potential of peramivir as a parenteral alternative to oral oseltamivir and inhaled zanamivir," explained Luke Chen, MBBS, FRACP, assistant professor of medicine in the Division of Infectious Diseases at Duke University in Durham, North Carolina.

"IV peramivir may finally fill a void in the current choices of anti-influenza therapy, because it can be administered to critically ill hospitalized patients who are unable to receive oral oseltamivir or inhaled zanamivir," he said.

Peramivir might also have a better pharmacokinetic profile for critically ill patients who are not able to absorb oseltamivir or zanamivir, Dr. Chen said. "So parenteral peramivir may be appropriate for patients who are unable to receive other recommended neuraminidase inhibitors. But its role in the treatment of swine-origin influenza A (H1N1) virus is uncertain and still needs to be defined," he said.

Dr. Kohno and colleagues noted that the next step in their research is a clinical trial on peramivir in pediatric patients with H1N1 influenza. "This trial may demonstrate the efficacy and safety of peramivir against 2009 H1N1 influenza," Dr. Kohno said.

Dr. Kohno reports being a consultant for Shionogi & Co. Dr. Chen has disclosed no relevant financial relationships.

49th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC): Abstract V-537a. Presented September 13, 2009.

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