Re-use of once failed regimen is possible?
Jan 7, 2012
Hi Doc, We imagine a scenario where after long use of a regimen based on 2 NRTIs and one NNRTI, all the HIV wild strains die and resistance strains get selected naturally and thus the regimen fail. Then the patient switches over to a second line with a protease inhibitor with tenofovir (if possible, we just imagine). And after long use of this second regimen again all the susceptibles die and the wild type again come in the population as majority along with the strains resistant against the first regimen. Is it possible to switch over again to the first regimen to get virological benefit based on the theory of natural selection? In brief, is it possible to re-use "a once upon a time" failed regimen?
Response from Dr. Young
Hi and thanks for posting your interesting question.
Generally speaking, once one's virus has developed resistance to a medication, that resistant virus remains in the body. This is because of the way that HIV infects cells, namely that the genetic library of the viral population becomes archived in the infected cells. Even after a second, or subsequent treatment regimen is used and the wild type population of virus is predominant, that archived resistant virus can rapidly reemerge once the "weakened" drug is reused. (This by the way is an unfortunate case study in real-time Darwinian evolutionary selection.)
So, it's not generally recommended to reuse medications that the virus had once upon a time had developed resistance.
Be well, BY
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