Drug holiday similar to a single missed dose?
May 29, 2003
I've got two questions about treatment.
1) In terms of drug resistance risk, is initiating a drug holiday similar to missing a single dose (of all meds in the regimen)?
2) Each drug has its own 'concentration profile' over time. When initiating a drug holiday, is this fact important? For example, suppose one of drugs in the regimen stays in the body significantly longer than the others. It would seem that a drug holiday would act like monotherapy (for a short time) for that drug. Does this pose a risk for resistance?
Thanks for the wonderful information on this site!
Response from Dr. Young
Thank you for your questions and thoughts.
Missing a single dose is rarely sufficient to cause problems with treatment failure or resistance. However, frequent missed doses can definately place one at risk for the development of resistance. Is it like a STI? I suppose the answer depends on how one structures the treatment interruption. In either case, missing doses or going on a treatment interruption should preferably only be done with medical and laboratory supervision.
As for your second question, yes, each drug does have it's own pharmacokinetic or concentration profile. Because of this, the way that one might plan on discontinuing a HAART regimen might theoretically depend on the nature of the drugs in the regimen. Yes, if some drugs have a very long life in the body and others a short half life, then effectively a person who stops therapy (like during a STI) might effectively on mono- or dual-antiretroviral therapy. Yes, this would place this person under considerable risk of developing drug resistance. Because of the uncertainty of the way that all drugs leave the body (more importantly, the CD4 cell), I'm not a big fan of structured (or unstructured) treatment interruptions, at least until we get a lot more information about the appropriate and safe way to do it. BY
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