A new study at the University of Rhode Island's College of Pharmacy shows that Roche's Tamiflu -- believed to be the best current weapon against a possible bird-flu pandemic -- can be rendered powerless in patients also taking Bristol Myers-Squibb's Plavix.
"Concurrent use of both drugs would inhibit the activation of oseltamivir (Tamiflu), thus making this anti-viral agent therapeutically inactive," said Bingfang Yan, head of a URI research team.
Yan said his study found that the presence of clopidogrel (Plavix's generic name), inhibited Tamiflu's hydrolysis -- which is a drug's decomposition through a reaction with water -- by as much as 90 percent.
"This is epidemiologicially significant because people who receive Tamiflu and Plavix simultaneously may maintain susceptibility to influenza or a source that spreads influenza if they are already affected," he said.
Yan said that, since patients who have had stroke, heart attack or peripheral artery disease would be among the high-risk individuals for contracting influenza of any strain, they could be among those getting Tamiflu and Plavix at the same time.
Yan said he has notified the Food and Drug Administration and the National Institutes of Health about the drug duo's possible effects. Yan said his team did a laboratory analysis of the two drugs and will next study the effects of the combination in human trials.
The results of the URI lab analysis will be published in the December issue of the Journal of Pharmacology and Experimental Therapeutics.