Experimental Drug Kills Flu Virus in a Single Day

Japanese drugmaker Shionogi claims its influenza virus treatment baloxavir marboxil, which is not yet on the market, is faster-acting than any other flu drug available, with just one dose of the medication effectively killing the virus within a single day, ScienceAlert reports.

In a Phase 3 clinical trial reported last year, the average amount of time the compound took to wipe out the virus in otherwise healthy adults was just over 24 hours.

In contrast, participants treated with one of the most common flu medications, oseltamivir (sold under the brand name Tamiflu), took 72 hours, and people taking a placebo required 96 hours to beat the virus.

While the overall time to alleviation of symptoms was similar whether participants took baloxavir marboxil or oseltamivir, Shionogi says its experimental drug provides immediate relief faster, which might curb the virus's contagiousness in people who take the treatment.

The oral drug works via a different biological mechanism to oseltamivir, which is a neuraminidase inhibitor, blocking an enzyme the virus uses to reproduce itself in infected cells.

By contrast, Shionogi developed baloxavir marboxil by leveraging discoveries made in anti-HIV drugs, targeting a different kind of enzyme and preventing cells from susceptibility to virus infection in the first place.

Another benefit is the single dose delivery, compared to oseltamivir's 10-dose regimen (two doses daily for five days), which isn't necessarily just a question of convenience, the drugmakers say.

"The advantage is that it's one pill once, versus a course of therapy, so particularly for pandemic planning, this could be an advantage," the head of co-developer Roche's pharma unit, Daniel O'Day, told Bloomberg.

"You don't have the potential resistance that comes with not completing your course of therapy."

According to Japanese newspaper The Asahi Shimbun, the drug, which targets both the A and B types of influenza virus, received a green light from a Japanese government health ministry panel in early February, indicating a likely go-ahead for imminent manufacture and sale of the drug.

Formal approval to do so is reportedly being fast-tracked and is expected to come in Japan next month, which means the treatment could be on sale there as soon as May.

As for future availability in the US and elsewhere, that's less clear right now.

According to The Wall Street Journal, Shionogi – together with Tamiflu maker Roche, who will have the rights to distribute baloxavir marboxil internationally – will apply for approval to sell the drug in the US this summer, with a decision expected to come sometime in 2019.