"The new drug sold as Xofluza is about as effective as Tamiflu in shortening flu symptoms and is expected to work against drugresistant strains. CreditGenentech via Associated Press the first new flu drug in  years won approval Wednesday from the Food and Drug Administration. The new antiviral generically known as baloxavir marboxil but sold under the brand name Xofluza is a single dose treatment. It is for use only in those aged  or more the F.D.A. said and should be taken only in the first two days after symptoms like fever aches and sniffles appear. The pill will cost  according to a spokeswoman for Genentech which will sell Xofluza in this country. Genentech will offer coupons that lower the price to  for patients with health insurance and to about  for the uninsured. Flu season has already begun and last years was one of the most lethal in decades about  Americans died of flu or its consequences https the Centers for Disease Control and Prevention said earlier this month. The new drug is no miracle cure and it is not approved for young children who are one of the most vulnerable groups so the C.D.C. still strongly recommends that every American over the age of six months get a flu shot as soon as possible. Advertisement Several other antiflu drugs exist  the bestknown of which is oseltamivir sold as Tamiflu  but none cure the illness quickly.  Also the influenza virus mutates very rapidly and has split into many strains that circulate simultaneously each winter and several have evolved resistance to older drugs. Having safe and effective treatment alternatives is critical said Dr. Scott Gottlieb the F.D.A. commissioner in a statement https This novel drug provides an important additional treatment option. Like the Science Times page on Facebook. httpon.fb.mepaTQh  Sign up for the Science Times newsletter. httpnyti.msMbHaRU Xofluza works in a new way by blocking an enzyme the virus needs to copy itself. So at least in theory circulating flu strains resistant to earlier drugs should not have any resistance to it.  It has been shown to work against both A and B strains which circulate each year and it is expected to work against dangerous bird flus known to occasionally infect humans such as the A strains of both HN and A HN.  Advertisement However it is virtually inevitable that resistance to Xofluza will evolve as more people use it. To prevent that doctors treat several diseases including H.I.V. and tuberculosis with cocktails of three or four different drugs but that is not the norm for flu treatment. Xofluza was invented by Shionogi a Japanese company that also created the statin Crestor. It does not cure a bout of flu as rapidly as for example antibiotics clear susceptible bacterial infections. But it may alleviate some symptoms and shorten the time that patients feel sick said Dr. Debra Birnkrant the F.D.A.s director of antiviral products. Xofluza was approved after two clinical trials in  patients. In both trials those treated with it recovered more quickly than those who got a placebo. In one trial there was no difference between Xofluza and Tamiflu. Tamiflu which is sold by Roche Genentechs parent company is now available cheaply as a generic drug. It requires two pills a day for five days.  Xofluzas most common side effects were diarrhea and bronchitis the F.D.A. said. Further research is underway to see whether it is safe and effective in children and whether it lowers rates of hospitalization and death. In June the F.D.A. granted Shionogi and Genentech priority review status https_trialsfdagrantspriorityreviewgenentechsbaloxavirmarboxilinfluenza.html expediting the approval process because it was considered an important drug. Sign up for Science Times Well bring you stories that capture the wonders of the human body nature and the cosmos. Donald G. McNeil Jr. is a science reporter covering epidemics and diseases of the worlds poor. He joined The Times in  and has reported from  countries."