It looks like you're using an Ad Blocker.
Please white-list or disable AboveTopSecret.com in your ad-blocking tool.
Some features of ATS will be disabled while you continue to use an ad-blocker.
Using single antiviral drugs to treat the current outbreak of swine influenza could result in the development of a resistant strain, a leading flu researcher said here. The virus is, however, susceptible to the neuraminadase inhibitors, oseltamivir (Tamiflu) and zanamivir (Relenza).
The risk is high that a strain resistant to all of these drugs could develop as long as the disease continues to be treated with single medications, Robert Webster, Ph.D., of St. Jude Children's Research Hospital in Memphis, said at the conference on Influenza Vaccines for the World.
"We can't continue to use single antiviral drugs. . . . The virus will win the game,"
up to 67% of seasonal H1N1 influenzas in Norway were resistant to oseltamivir during the 2007-2008 flu season, according to Jennifer McKimm-Breschkin, Ph.D., of CSIRO Molecular & Health Technologies in Australia.
This occurred even though Norwegian doctors made very little use of oseltamivir, illustrating the ability of resistance to develop without any drug treatment.
Anti-viral drug Tamiflu must be used with care to avoid the new strain of swine flu developing resistance, an expert on infectious diseases has warned.
On Wednesday, the CDC reported that influenza A H1N1 viruses from 13 patients with confirmed diagnoses of swine flu had been tested for resistance to a variety of antiviral drugs. The good news was that all of the isolates were susceptible to the antiviral drugs oseltamivir (Tamiflu) and zanamivir (Relenza). However, all 13 were resistant to adamantane-based drugs (amantadine and rimantadine). Resistance to adamantane drugs (which were developed first) has actually become quite widespread among flu viruses in general, so oseltamivir and zanamivir are commonly the drugs of choice.
This swine influenza A (H1N1) virus is sensitive (susceptible) to the neuraminidase inhibitor antiviral medications zanamivir and oseltamivir. It is resistant to the adamantane antiviral medications, amantadine and rimantadine.
An escalation of the outbreak will be a real-life experiment of how much protection the drugs provide should a flu pandemic erupt, said Brian Currie, medical director for research at Montefiore Medical Center in the Bronx and an infectious-disease specialist.
It's also a test of human behavior. After the 2001 anthrax scare, the antibiotic Cipro disappeared in six hours from Montefiore's pharmacy. Doctors prescribed it for each other and for relatives.
Already, some flu victims in New York said, their pharmacies have run out of Tamiflu.
January 15th, 2009 By Kyung M. Song
One of the major strains of the influenza virus this season has become resistant to Tamiflu - rendering the mainstay antiviral drug all but impotent and creating tough treatment options for patients who come down with the flu.
On Dec. 19, the federal Centers for Disease Control and Prevention (CDC) alerted local health authorities that an early testing of the most common type of seasonal flu found that it has become virtually impervious to Tamiflu.
The resistance, apparently triggered by a spontaneous mutation in the virus, comes three years after a different subtype of the flu virus became widely resistant to another drug class.
A new University of Colorado at Boulder study shows the resistance of the avian flu virus to a major class of antiviral drugs is increasing through positive evolutionary selection, with researchers documenting the trend in more than 30 percent of the samples tested. The avian flu, an Influenza A subtype dubbed H5N1, is evolving a resistance to a group of antiviral drugs known as adamantanes,
In contrast, resistance of the avian flu virus to the second, newer class of antiviral drugs that includes oseltamivir -- a prescription drug marketed under the brand name Tamiflu -- is present, but is not yet prevalent or under positive genetic selection.
Dr David Hill on why antiviral vaccines are not the answer to a possible swine flu pandemic, and why more fundamental action is needed. For for all the above reasons, an international and national strategy based on a drugs solution is not the answer; we have to look at how animal flu makes the transition to humans.