Don't put only one flu drug in your stockpile basket, scientists are saying. To keep antiviral resistance at bay, countries are better off with more than one option. In fact, a mathematical model showed that using both Roche's Tamiflu and GlaxoSmithKline's Relenza cut the proportion of flu-infected patients to 58 percent from 68 percent--and perhaps more importantly, slashed the chance of resistance emerging to just 2 percent from 38 percent.
But--and this is a big "but," given the fact that the H1N1 A strain now circulating appears to be relatively mild--the safety of combination therapy hasn't been studied. So, the Hong Kong researchers concluded, countries should first use the drug that's the smallest part of their stockpiles, then switch to the dominant drug. That way, resistance to the dominant drug could be delayed for as long as possible.
Given the fact that Tamiflu accounts for the lion's share of global stockpiling, that means Relenza should be deployed first, they said. Once Relenza stocks run low, then officials could hit the disease with Tamiflu. Another approach: Using one drug to treat active flu and the other as a prophylactic. This method also delays the emergence of resistance, previous research has shown.
Other scientists concurred that strategically using the two meds could up their overall effectiveness against a possible pandemic. "Cross-resistance to both drugs at the same time is highly unlikely, so using the two drugs cleverly might be able to delay the emergence of resistance," epidemiologist Jodie McVernon at Melbourne University, who was not involved in the study, told New Scientist.