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How many doses of meds can I miss?
Jul 24, 2005

I recently started meds and my doctor told me that it is important not to miss doses because of the risk of resistance developing. I have so far missed 2 doses. Is that enough to become resistant or do I have to miss a lot of doses for that to happen?

Response from Dr. Sherer

Your best chance of minimizing the chance of drug resistance and regimen failure is to take all doses. Even a single missed dose could open the door to resistance, particularly in the case of the NNRTI-based regimens, in which two agents, e.g. efavirenz and lamivudine, are vulnerable to resistance with just a single amino acid mutation.

Most ART regimens are given either once or twice daily. Of the 14 weekly doses in a twice daily regimen, the evidence suggests that missing one of the 14 doses weekly is still associated with an optimal outcome; with more than one miss per week, the chances of resistance and regimen failure increase.

With once daily regimens, the evidence suggests one missed dose every two weeks is associated with optimal outcomes.

The answer may differ with different regimens, as I noted with the NNRTIs above. Boosted PIs appear to be less vulnerable to resistance, and their use also reduces the risk of resistance to the other members of the regimen.

I suggest you focus on ways to reduce your missed doses as much as possible. When you realize you are late with a dose, take the dose then, rather than waiting for the next usual dosing time, and then resume treatment at your usual times. And I suggest that you talk to your doctor about this question, as he or she is likely to have important information about your health and health care that I lack, for example the specific ART regimen that you are taking.

undetectable without meds?
Adherence Worry

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