Protease inhibitor drug levels in the management of human immunodeficiency virus-1 antiretroviral therapy.

In order to evaluate the relationship between protease inhibitor (PI) plasma concentrations and viral suppression in individuals receiving highly active antiretroviral therapy (HAART), plasma concentrations and area under the time concentration curve (AUC(0.5-4)) for 35 HIV-infected adults receiving their initial (or first salvage) nelfinavir- (NFV) or indinavir (IDV)-based HAART were studied. Two groups were evaluated: those who had achieved HIV-RNA suppression (HIV-RNA <500 copies/mL, group 1, n=21) and those who had achieved incomplete HIV-RNA suppression (HIV-RNA>500 copies/mL, group 2, n=14) at the time of study entry. NFV one-hour pre-dose concentrations were significantly higher in group 1 compared to group 2 (P=0.023). The NFV AUC(0.5-4) for group 1 approached significance (P=0.068). No significant differences in IDV concentrations or AUC(0.5-4) were found between group 1 and group 2. It is feasible to use PI drug level monitoring in the outpatient setting.