From Crixivan to viramune
Mar 8, 2001
Hi, I have been on crix+combivir for about 5 years with great success. My viral load was <50 and T 880 as of the last time I was tested. Timing and food restrictions almost made me stop taking the medications. I asked my doctor for other options and he said right away "lets do viramune". (I had tried the crix+norvir but lipids and cholesterol went up.)I was very skeptical if this new combo would be strong enough for my situation. He said that he has been switching patients from crix to viramune with success in the same situation I was. I had not started crix and combivir together. I had added crix to combivir and I have been reading that switching to viramune will not be a good idea because there might be some resistance in combivir. I am in my first week of viramune now. In 3 weeks I am going back for lab tests. I am only hoping that this new combo will work for me, because it has given my such a great relief already. I am worry though,if it doesn't work would I be able to go back to crix and achieve the same good old results?
Response from Dr. Cohen
Well - you are right on target with the concerns you raised about the switch.
We have learned that there are a few factors that differ between these antiviral meds. One is this concept of the genetic barrier to resistance. This means, simply - how hard is it for HIV to create resistance to this particular medication? We have learned that it is harder for HIV to create resistance to a protease inhibitor like Crixivan/indinavir than it is for it to create resistance to a nonnucleoside like Viramune/nevirapine. Now, if either are used in a fully potent triple combo - they might work equally well. The three drug combo creates a strong barrier to resistance.
But - if we give ONLY Crixivan - as we did in the initial studies - about 30% had viral load suppression lasting at least six months. If we give ONLY viramune - viral suppression will last maybe two weeks and then everyone would have resistance to the viramune - since it is much easier for HIV to create resistance to this medication than to Crixivan.
So - in your case - you are somewhere in between - in that you are using viramune in a triple combo - but might have some resistance to the other two meds. The key here is how much resistance you have in the AZT and the 3TC (the two meds in Combivir), and perhaps, how high your viral load was before you started meds. If you just had a little bit of resistance to the meds in Combivir - and if your viral load is on the lower side before you started treatment - then this switch could work for you. But if you have resistance to both AZT and 3TC - and had a higher viral load - it is possible this switch may not be as successful. It may be impossible to know how much resistance you had before making this switch - so, it may be that you will just need to measure the viral load as planned and see if it worked. One predictor is how long you were on Combivir before adding Crix - but this is only a crude predictor.
However - if this switch doesn't work - it would likely be because of some resistance to the Combivir. And, odds are good that the only new resistance you would get at least initially is to the viramune - in the first month, you probably would not get more mutations to the AZT and 3TC than you already have. So this means that it is likely you could just go back to the Combivir and Crixivan and reestablish control. But if it doesn't work - it might be worth getting a resistance test - to take a picture of what your HIV resistance pattern is - since the problem was that you found this combo difficult to deal with - and a resistance test could help you plan for some other combo if this one doesn't work.
Good luck. CC
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