Oct 29, 2005
what other drugs are being used when a patient develops resistance to azt?
Response from Dr. Sherer
Resistance to AZT takes the form of thymidine associated mutations or TAMs. Full cross resistance appears to occur with D4T (stavudine) when present with AZT. As with most other NRTIs, several mutations are needed before complete resistance to AZT is established. Hence it is common to have partial resistance to AZT rather than complete resistance.
In the presence of AZT resistance, there may be options both within the NRTI class - such as DDI, abacavir, or tenofovir - and options for regimens that do not use the NRTIs, such as an NNRTI and a protease inhbitor.
Also, resistance to AZT is a special case, in that the use of 3TC in the presence of AZT resistance can promote the development of viral strains that are less resistant (i.e. more susceptible), so in situations where the continued use of AZT is desirable, the addition of 3TC is often considered.
There are also new drugs in development, such as DD4FC, that have activity against viruses that are fully resistant to AZT and most of the other NRTIs.
I advise you to talk to your physician about resistance in general, and the options in the setting of AZT resistance.
Stop meds program
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