Efficacy of nelfinavir in patients switched from ritonavir/saquinavir combination antiretroviral therapy.

Unlabelled: Based on available data and expert opinion, the IAS-USA treatment guidelines recommend "selective substitution" of the medication thought most likely to be causing a side effect for one that should have a different side effect profile.
Purpose: This study evaluates the short-term virological efficacy of selective substitution with nelfinavir-nucleoside combination therapy in individuals with plasma viral RNA below 400 copies/mL.
Method: This study involved a retrospective chart review at five large urban HIV Clinical practice settings and included 19 patients taking combination therapy including ritonavir with saquinavir. We performed selective substitution with a nelfinavir combination. Our main outcome measure was plasma HIV-1 RNA (Amplicor) obtained during the period between weeks 12 to 18.
Results: We identified 19 HIV-1-infected individuals with evidence of viral suppression as defined by a viral load below 400 copies/mL while taking dual nucleoside reverse transcriptase inhibitors with ritonavir/saquinavir. Reasons for switching included adverse effects (37%) or preference for nelfinavir due to the possibility of a better defined salvage regimen (63%). We defined a composite viral endpoint indicative of continued viral suppression using the first 12 to 18 weeks following the medication change. We found that 73% maintained undetectable viral loads (plasma HIV RNA below 400 copies/mL) during this period.
Conclusion: These data suggest that any medication adjustment should be made cautiously, as there may be some potential risk in a substitution. Selective substitution of a medication that has undesirable side effects or other characteristics should be considered when the possible risks of the loss of viral suppression are outweighed by the potential benefits of that substitution.