Human immunodeficiency virus type 1 (HIV-1) strains dually resistant to zidovudine and lamivudine (3TC) may arise during zidovudine-3TC combination therapy. The objective of this cross-sectional study (n = 43 patients) was to test the association between therapy response (clinical and immunologic) to zidovudine-3TC and the level of phenotypic zidovudine resistance and zidovudine resistance-associated genotype of 3TC-resistant isolates. Other variables included were baseline CD4+ cell count, baseline Centers for Disease Control and Prevention (CDC) classification, virus load, and time receiving zidovudine. Phenotypic resistance was assessed using a recombinant virus assay. Genotypic analysis was based on population sequencing of plasma HIV-1. In a univariate analysis using a logistic regression model, it was found that therapy response was significantly associated with phenotypic and genotypic zidovudine resistance, baseline CD4+ cell count, and virus load. After adjustment for all variables, phenotypic resistance to zidovudine remained the only significantly associated factor, independent of baseline CD4+ cell count, baseline CDC classification, and virus load.

The association between CD4 cell count and duration of virus load suppression was investigated in 558 patients in the Frankfurt HIV Clinic Cohort who had begun highly active antiretroviral therapy and who had virus load declines to 500 copies/mL; P=.0001). Baseline virus load was not associated with virus load rebound. Lower baseline CD4 cell counts were associated with increased risk of viral rebound; however, this risk was significantly reduced in persons with low baseline CD4 cell counts who experienced substantial increases in CD4 cell counts during follow-up.

HAART-treated patients with high viral loads and CD4 cell counts experienced reduced disease progression compared with individuals with the same CD4 cell count and viral load not receiving HAART. Consequently, the short-term prognosis associated with viral load levels and CD4 cell counts may differ in patients on HAART. Whether this effect will be observed with non-protease-inhibitor-containing HAART is not known at this time.

Background-The extent to which the prognosis for AIDS and death of patients initiating highly active antiretroviral therapy (HAART) continues to be affected by their characteristics at the time of initiation (baseline) is unclear.Methods-We analyzed data on 20,379 treatment-naive HIV-1-infected adults who started HAART in 1 of 12 cohort studies in Europe and North America (61,798 person-years of followup, 1844 AIDS events, and 1005 deaths).Results-Although baseline CD4 cell count became less prognostic with time, individuals with a baseline CD4 count <25 cells/µL had persistently higher progression rates than individuals with a baseline CD4 count >350 cells/µL (hazard ratio for AIDS = 2.3, 95% confidence interval [CI]: 1.0 to 2.3; mortality hazard ratio = 2.5, 95% CI: 1.2 to 5.5, 4 to 6 years after starting HAART). Rates of AIDS were persistently higher in individuals who had experienced an AIDS event before starting HAART. Individuals with presumed transmission by means of injection drug use experienced substantially higher rates of AIDS and death than other individuals throughout follow-up (AIDS hazard ratio = 1.6, 95% CI: 0.8 to 3.0; mortality hazard ratio = 3.5, 95% CI: 2.2 to 5.5, 4 to 6 years after starting HAART).Conclusions-Compared with other patient groups, injection drug users and patients with advanced immunodeficiency at baseline experience substantially increased rates of AIDS and death up to 6 years after starting HAART.

The objective of this study was to evaluate the pharmacokinetics of atazanavir (ATV), saquinavir (SQV), and ritonavir (RTV) in a boosted double-protease inhibitor (PI) therapy regimen without reverse transcriptase inhibitors (RTIs). The study design was as follows. Patients with limited RTI options received a PI combination of 300/100 mg ATV/RTV once daily and 1,000 mg SQV twice daily (group 1; n ‫؍‬ 49) without RTI comedication. The results were compared to the plasma concentrations of PIs of patients taking either 300 mg ATV/100 mg RTV once daily plus RTIs (group 2; n ‫؍‬ 72) or patients taking 1,000 mg SQV/100 mg RTV plus RTIs (group 3; n ‫؍‬ 90). The study methods were as follows. Patients were given a 12/24-h pharmacokinetic assessment at steady state. Drug concentrations were measured by liquid chromatography-tandem mass spectrometry. The minimum and maximum concentrations (C min and C max ), area under the concentration-time curve under steady-state conditions (AUC ss ), elimination half-life, time of maximum concentration and lag time were subject to statistical analysis. The results show that patients treated with ATV/SQV/RTV exhibited significantly high SQV concentrations and moderate enhancement of the AUC ss of ATV in comparison to those of patients of the control groups: for SQV in groups 1 and 3, the geometric mean (GM) of the AUC ss was 22,794 versus 15,759 ng ⅐ h/ml (GM ratio [GMR] ‫؍‬ 1.45; P < 0.05), the GM of the C max was 3,257 versus 2,331 ng/ml (GMR ‫؍‬ 1.40; P < 0.05), and the GM of the C min was 438 versus 437 ng/ml (GMR ‫؍‬ 1.00); for ATV in groups 1 and 2, the GM of the AUC ss was 39,154 versus 33,626 ng ⅐ h/ml (GMR ‫؍‬ 1.16), the GM of the C max was 3,488 versus 2,924 ng/ml (GMR ‫؍‬ 1.20), and the GM of the C min was 515 versus 428 ng/ml (GMR ‫؍‬ 1.21). RTV levels were comparable for all groups. A subgroup analysis detected only marginal differences in ATV plasma exposure if combined with tenofovir-disoproxilfumarate and without it. We conclude that our pharmacokinetic results support the use of a boosted double-PI regimen of ATV/SQV/RTV as a treatment option for patients who need antiretroviral therapy without RTIs.