Triomune 30 is the combination of stavudine/lamivudine/nevirapine in one pill. Atripla is tenofovir/emtricitabine/efavirenz in one pill.
If one is doing well on Triomune 30 there would be little reason to switch except for concern for the long term toxicity of this medication, particularly the stavudine. It is well known that stavudine causes problems with numbness and tingling of the feet and hands (peripheral neuropathy), elevated cholesterol and loss of limb and facial fat. For these reasons, this drug is hardly used in the US now. However, Triomune is cheap and therefore commonly relied upon in other parts of the world.
If a reliable generic Atripla was available and affordable, I would prefer that to Triomune. The tolerability longer term would be much better in most people. Unfortunately, if a patient is experiencing virologic failure of Triomune, it is unlikely Atripla will help much as virus that is resistant to the agents within Triomune would not be expected to respond to Atripla. If the viral load is undetectable but the CD4 dropping it is possible a switch to Atripla might help.
DW