New fast-acting flu drug first reviewed by FDA

A pill that helps control the symptoms of the flu after a dose quickly receives the attention of the Food and Drug Administration, the company said Tuesday.

Genentech said the FDA had granted priority consideration to Baloxavir marboxil and would decide to approve it by the end of the year.

If it is approved, baloxavir would be the first new flu medicine to hit the US market for years and the first with a new mechanism of action in 20 years.

"Baloxavir marboxil has been shown in clinical trials to reduce the duration of symptoms with a single dose, and has shown a significant reduction in viral shedding in a single day," said Dr. Sandra Horning. .

Influenza viruses have developed resistance long ago to the first two antiviral flu drugs, amantadine and rimantadine.

The most recent antiviral drugs on the market include Tamiflu, a pill; Relenza, which can be inhaled; and an injectable drug called peramivir.

All three are in a class called neuraminidase inhibitors. They help prevent the virus from spreading inside the body and work best when it is administered within a day or two of beginning symptoms.

Even though antivirals do not cure the flu as an antibiotic can cure strep throat, they are still helpful, says the CDC. They reduce the duration of the disease and make it less likely to kill them. Tamiflu can also be used to prevent infection in really vulnerable groups, such as young children and nursing home residents.

Baloxavir, already approved in Japan, works differently. It interferes with a protein inside the influenza virus called cap-dependent protein endonuclease.

It also helps stop virus replication, but earlier in the process. "It inhibits the virus much earlier in the life cycle of the flu," said Genentech vice president Mark Eisner.

"It's going to be more convenient than neuraminidase inhibitors because it works after a single dose," Eisner told NBC News.

A 2016-17 study of 1,436 people in the United States and Japan showed that the single-dose pill reduced the duration of the disease to 2.5 days after 3.3 days. It has reduced the duration of fever from 42 hours to a day and reduced what is called viral shedding from four days to a single day.

Reducing viral shedding should, in theory, limit the spread of the virus from one person to the other, although society has not demonstrated it.

This did not cause a lot of side effects.

The company has continued testing the product in more people, including people at high risk of flu complications, and is now analyzing the results, Eisner said.

Tamiflu is now recommended for children and people who are at high risk of influenza, but patients should take multiple doses over several days. Relenza is used less, but peramivir and peramivir are more useful for hospitalized patients who may be unable to take tablets.

Doctors like to have a variety of drugs on hand for any disease, but especially the flu, which mutates quickly and can develop resistance to drugs. In 2009, for example, the H1N1 swine flu strain developed Tamiflu resistance.

Baloxavir is sold in Japan by its inventor Shionogi & Co. under the name Xofluza. Genentech did not say what would be the name of the United States if the FDA approved it.

"The FDA should make a decision on approval by December 24, 2018," the company said. Representatives of the company said that it was too early to talk about a name for the US product or what it might cost.