Why do you suppose Roche didn't mention this?

"As health authorities around the world try to work out how to deal with a possible flu pandemic, an American doctor has come up with a potential solution to any drug shortage, and it's a solution that goes back more than six decades. The Oregon-based Dr Joseph Howton from the Adventist Medical Centre says using the antiviral treatment Tamiflu, together with a drug called Probenecid, makes the flu treatment last twice as long. It's a technique similar to that used during World War II to preserve supplies of penicillin."

Dr. Howton said, "Recently, I was reviewing the studies and also Tamiflu, and I found that they talk about being careful when you use Probenecid with also Tamiflu, because it raises the drug level. And I thought about it from the opposite perspective – well this is great, this a wonderful side effect, why don't we consider using Probenecid to, exactly for that reason, we have this tremendous shortage of the drug.

"And there was one study in 2002 that documented the profound effect of Probenecid on Tamiflu, it, actually it increased the level by two and a half times, and at that time it wasn't really being looked at as an issue of, you know, something to use during a shortage. But if you look at Tamiflu the same way we looked at penicillin during World War II, and penicillin was in very short supply, and as a result we gave Probenecid with penicillin to enhance the effect and extend the supplies, why not use that same idea for Tamiflu."

http://www.abc.net.au/worldtoday/content/2005/s1496227.htm