Safety, Tolerability, and Antiretroviral Effects of Ritonavir-Nelfinavir Combination Therapy Administered for 48 Weeks [Raines CP, et al. JAIDS 2000; 25:322]: This study from Hopkins tested the combination of ritonavir and nelfinavir with two dosage regimens: RTV 400 mg plus NFV 500 mg bid versus RTV 400 mg plus NFV 750 mg bid. Participants were PI-naïve with HIV viral loads >5,000 c/mL. There were 20 patients, 10 in each of the two groups. There was an option to add nucs at week 12, which was elected for 15 of the 20 participants. Results showed that 4 of 12 patients completing 48 weeks of therapy had a viral load <20 c/mL. The major side effect was diarrhea in 9 of the 20 participants. The average CD4 cell count increase was 158/mm³ at 48 weeks. Genotypical analysis showed no emergence of primary resistance mutations. The authors concluded that the virologic and CD4 cell count response in PI-naive patients was comparable for RTV plus NFV compared to other PI combination regimens, and it had the possible advantages of twice-daily dosing, low pill burden, and reduced cost. The optimal dose was not established in this study.
Comment: Nelfinavir is the only PI that seems to be commonly used as a single PI in most HAART regimens. Of the currently available agents in this class, this is the one that seems to demonstrate the least benefit by the addition of RTV. Nevertheless, there appeared to be a pharmacokinetic interaction that was favorable in this study, although PK data are to be reported later in more detail. This is a limited study, but the two regimens tested appeared to be comparable in virologic outcome, CD4 cell count response, side effects, and pharmacology.
posted 1/4/2001

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