Hello, after six months on Sustiva/Videx/Epivir, I've developed resistance to Epivir. My doctor wants to switch over to Viread. He claims that the mutation that led to Epivir resistance actually makes Viread more effective. Do you know anything about this, or have any opinion about this switch? I'm upset to have developed this resistance so quickly after beginning therapy (I never missed a dose). I'm hoping to have better luck on my next regimen and want to choose it wisely. Thanks!

Well, that's not something that I would necessarily feel comfortable doing unless I was absolutely sure you had no other resistance to the other drugs you were on. While the resistance mutation that causes resistance to Epivir (M184V) does make Viread more effective, it also decreases the effectiveness of Videx to a lesser extent. I would consider changing the nucleoside backbone entirely, if you have that option. I presume the resistance test showed no resistance to Sustiva, but if your viral rebound was particularly impressive, I would presume resistance to the whole regimen and change it all, again assuming that you have natiretroviral options remaining. I am not an advocate of changing just one drug, and I am unaware of any studies that support that approach.