Triple nucleoside treatment with abacavir plus the lamivudine/zidovudine combination tablet (COM) compared to indinavir/COM in antiretroviral therapy-naïve adults: results of a 48-week open-label, equivalence trial (CNA3014)

OBJECTIVE

An equivalence (non-inferiority) trial comparing antiviral response, tolerability, and adherence with a triple nucleoside regimen containing abacavir 300 mg (ABC) plus a lamivudine 150-mg/zidovudine 300-mg combination tablet (COM) twice daily vs. a regimen containing the protease inhibitor indinavir (IDV) 800 mg three times daily plus COM twice daily (IDV/COM) in antiretroviral-naïve, HIV-infected patients.

METHODS

Adult patients with plasma HIV-1 RNA levels > or = 5000 copies/mL and CD4+ cell counts > or = 100 cells/mm(3) were randomized to receive open-label ABC/COM (n = 169) or IDV/COM (n = 173) for 48 weeks. The intent-to-treat (ITT) population was the primary population evaluated. ITT: switch/missing equals failure (ITT: S/M = F) and as-treated (AT) analyses were used for assessing the proportion of patients achieving plasma HIV-1 RNA level < 400 and < 50 copies/mL at each clinic visit. In the ITT: S/M = F analysis, patients who switched treatment or had missing values were considered treatment failures; the AT analysis examined virologic data only while patients received study treatment. ABC/COM was considered equivalent (non-inferior) to IDV/COM if the lower limit of the 95% confidence intervals (CIs) about the difference in proportions of ABC/COM- vs. IDV/COM-treated patients attaining plasma HIV-1 RNA < 400 copies/mL exceeded -15% at week 48.

RESULTS

The study population was diverse with respect to ethnicity (38% Asian, 27% Hispanic, 28% white, 3% black, 4% other) and gender (39% women, 61% men). Baseline median HIV-1 RNA was 4.80 log(10) copies/mL and CD4+ cell count was 315 cells/mm(3). ABC/COM met the criterion of equivalence to IDV/COM. In the ITT: S/M = F analysis at Week 48, a greater proportion of ABC/COM-treated patients achieved HIV-1 RNA < 400 copies/mL (66% [109/164] vs. 50% [82/165]; treatment difference 16.6%, 95% CI (6.0, 27.2), p = 0.002) and HIV-1 RNA < 50 copies/mL (60% [99/164] vs. 50% [83/165]; treatment difference 9.6%, 95% CI [-1.1, 20.2]), whereas the AT analysis showed similar proportions achieving these endpoints (< 400 copies/mL: 85 vs. 83%; < 50 copies/mL: 79 vs 81%). Comparable proportions of patients with screening HIV-1 RNA values > 100 000 copies/mL achieved HIV-1 RNA < 400 copies/mL (ABC/COM: 60% [35/58]; IDV/COM: 51% [33/65]; treatment difference 9.6%, 95% CI [-7.9, 27.1]; ITT: S/M = F analysis). A significantly greater proportion taking ABC/COM were > or = 95% adherent (72% [109/151] vs. 45% [70/154] with IDV/COM, p < 0.001). Median increases from baseline in CD4+ cell counts were similar in the two treatment groups (+148 vs. +152 cells/mm(3)). Significantly more patients on IDV/COM reported drug-related adverse events (87% [142/165] vs. 65% [108/164] with ABC/COM, p < 0.001), similar proportions discontinued treatment due to adverse events (13 vs. 10%), and a slightly greater proportion in the ABC/COM group reported serious adverse events (13 vs. 8%). About half of the latter comprised suspected ABC-related hypersensitivity reactions (overall rate, 6%). Most adverse events were gastrointestinal in nature in both treatment groups.

CONCLUSION

ABC/COM was at least equivalent to IDV/COM over 48 weeks in the treatment of antiretroviral-naïve patients. ABC/COM was associated with a significantly higher adherence rate and lower incidence of drug-related adverse events than IDV/COM. The study was limited in that it was not powered to determine equivalence of treatments within high vs. low viral load strata, adherence was not monitored electronically, and bias could not be ruled out due to the open-label study design.

Predictors of adherence and virologic outcome in HIV-infected patients treated with abacavir- or indinavir-based triple combination HAART also containing lamivudine/zidovudine

OBJECTIVES

To compare dosing convenience and adherence with abacavir (ABC) 300 mg plus a fixed-dose lamivudine 150 mg/zidovudine 300 mg combination tablet (COM) twice daily versus indinavir (IDV) plus COM twice daily in treatment-naïve, HIV-1-infected adults; and to evaluate the association among difficulty taking antiretroviral regimens, adherence, and virologic efficacy.

METHODS

An open-label, randomized, multicenter, international study compared the COM/ABC and IDV/COM regimens with respect to self-reported adherence and regimen convenience over 48 weeks. Logistic regression analysis (LRA) was done on a patient sub-sample from both groups to evaluate predictors of adherence and virologic response at last time-point on randomized therapy (LTORT).

RESULTS

The study population was diverse with respect to ethnicity (38% Asian, 27% Hispanic, 28% white, 3% black, 4% other) and gender (39% women, 61% men). Baseline median HIV-1 RNA was 4.80 log(10) copies/mL and CD4+ cell count was 315 cells/mm(3). Of 329 patients who were randomized and received treatment, 315 (96%) provided adherence data. Significantly more patients in the ABC/COM group than in the IDV/COM group reported > or = 95% adherence to therapy (76 vs 58%, p < 0.001) and no difficulty in taking their regimen (91 vs 61%, p < 0.001). In both groups, the highest probability of HIV-1 RNA < 400 copies/mL occurred when median adherence was > or = 95%. The probability of HIV-1 RNA < 400 copies/mL declined more rapidly in the IDV/COM group as adherence rates decreased. LRA showed that no difficulty taking any of the drugs in the regimen, ABC/COM treatment group, and male gender were independent significant predictors of > or = 95% adherence (p < 0.05). Median adherence and baseline HIV-1 RNA were significant predictors of HIV-1 RNA < 400 copies/mL (p < 0.05).

CONCLUSIONS

Patients reported greater ease of use and superior adherence to ABC/COM than IDV/COM. Patient-reported difficulty taking drugs in a regimen was predictive of reduced adherence, and both of the latter factors were predictive of poorer virologic outcome. Adherence levels of > or = 95% in both treatment groups maximized the probability of patients achieving an HIV-1 RNA < 400 copies/mL.

Indinavir and rifabutin drug interactions in healthy volunteers

Two studies examined the pharmacokinetics of indinavir and rifabutin when coadministered in healthy subjects. Rifabutin, which induces the expression of cytochrome P450 (CYP) 3A, and indinavir, which inhibits that enzyme system, are frequently coadministered in patients infected with HIV. The second study was undertaken to determine if altering the dose of rifabutin coadministered with indinavir would minimize the drug interaction observed in the first study. Two studies, each with a three-period crossover design, were performed. In study 1, standard doses of rifabutin and indinavir (300 mg of rifabutin qd and 800 mg indinavir q8h) were administered as monotherapy (with placebo to the other drug) or in combination to 10 volunteers for 10 days. In study 2, 150 mg qd of rifabutin together with 800 mg q8h of indinavir, 300 mg qd of rifabutin alone, or 800 mg q8h of indinavir alone was administered to 14 volunteers for 10 days. In study 1, the geometric mean ratio (GMR) (90% confidence interval [CI]) of the AUC((0-8h)) of indinavir, coadministered with rifabutin 300 mg qd compared to indinavir alone (with rifabutin placebo), was 0.66 (0.56, 0.77), while that of the AUC((0-24h)) of rifabutin, coadministered with indinavir compared to rifabutin alone (with indinavir placebo), was 2.73 (1.99, 3.77). In study 2, the GMR (90% CI) of the AUC((0-8h)) of indinavir, coadministered with rifabutin 150 mg qd compared to indinavir alone, was 0.68 (0.60, 0.76), while that of the AUC((0-24h)) of rifabutin, when rifabutin 150 mg qd was coadministered with indinavir compared to rifabutin 300 mg qd alone, was 1.54 (1.33, 1.79). For both studies 1 and 2, indinavir and rifabutin administered alone or in combination were generally well tolerated. No clinical or laboratory adverse experience was serious. These data demonstrate the important pharmacokinetic interactions between indinavir and rifabutin when they are coadministered. Indeed, these observations formed the basis for the subsequent ACTG 365 study that explored dose adjustments for these agents in combination regimens to preserve the sustained antiviral activity of indinavir in the absence of adverse events as a result of elevated circulating levels of rifabutin.

Efficacy of two modalities of triple HIV therapy: probable superiority of indinavir

The introduction of the so-called highly active antiretroviral therapies has had an impact on the natural history of the HIV infection. The aim of this contribution is to assess the differences in terms of plasma viral load (VL), as a reflection of therapy success or failure. A retrospective study was made of the changes in VL in two cohorts of patients depending on the drugs included in the triple therapy prescribed to them. The comparison of the triple therapies containing any reverse transcriptase inhibitor and different protease inhibitors, indinavir (IDV) (239 patients) versus saquinavir (SQV) or ritonavir (RTV) (138 subjects), showed a significantly higher percentage of patients reaching a 'non-detectable' VL among those receiving indinavir (67.8% versus 54.3%; P = 0.011). The interval before VL levels rose above 30,000 RNA copies/ml was different in the two groups: 385 days (276-495 days) for therapies including indinavir, and 239 days (86-391 days) for saquinavir or ritonavir. This seems to support the excellent behaviour of indinavir when its efficiency is compared with other protease inhibitors acting as potential competitors.

Comparison of two reduced-dose regimens of indinavir (600 mg vs 400 mg twice daily) and ritonavir (100 mg twice daily) in healthy volunteers (COREDIR)

OBJECTIVE

To assess the pharmacokinetics and tolerability of reduced dosages of twice daily indinavir (IDV) boosted by low-dose ritonavir (RTV) in healthy volunteers.

METHODS

Pharmacokinetics and tolerability of IDV/RTV twice daily (600/100 mg and 400/100 mg) were assessed in a randomized crossover design in 16 healthy volunteers. Each dosage was taken twice daily for 2 weeks before 12 h pharmacokinetics were obtained.

RESULTS

Sixteen subjects were included, with a mean age +/- SD of 30 +/- 4 years; seven female, nine male. Fifteen subjects completed the study. After dose reduction of IDV AUC, Cmax and Cmin decreased significantly. In the 400 mg group three out of 15 subjects had IDV levels below 0.10 mg/l vs none in the 600 mg group. All subjects reported mild to moderate side effects throughout the study period, which were more severe in the 600 mg group (mostly renal, dry skin/lips, paresthesias/oral discomfort). In the 600 mg group four subjects reported dysuria and one subject discontinued because of flank pain, whereas two subjects reported dysuria and no subject discontinued in the 400 mg group, respectively. Eight subjects developed crystalluria without a significant difference between both groups. No significant change in serum creatinine was observed.

CONCLUSIONS

IDV/RTV 400/100 mg twice daily resulted in significant lower IDV exposure, with three out of 15 subjects revealing Cmin values below the recommended threshold for wild-type virus of 0.10 mg/l. Tolerability, however, was lower in the 600 mg IDV group. Therapeutic drug monitoring in the individual patient appears to be necessary to guarantee appropriate drug levels and simultaneously minimize toxicity.

Lopinavir/ritonavir vs. indinavir/ritonavir in antiretroviral naive HIV-infected patients: immunovirological outcome and side effects

We compared immunovirological outcomes and toxicities of HAART regimens including LPV/r and IDV/r in antiretroviral naïve HIV-1 patients. We retrospectively selected 55 patients starting LPV/r and 52 starting IDV/r as first-line HAART. Immunovirological and metabolic parameters were recorded at baseline and every 3 months as were side effects, AIDS-defining events and deaths. Demographic characteristics and NRTIs included in the regimens were comparable. Both groups reached undetectable HIV-RNA plasma viremia from third month and maintained during follow-up. However, patients receiving IDV/r had a lower probability to obtain virological success (RH: 0.46). Patients receiving IDV/r patients showed a greater increase of total cholesterol (P = 0.01). Three patients on LPV/r and 21 on IDV/r discontinued the drug for toxicity, leading to a 8.40 higher risk of discontinuation in the latter group. In our clinical setting IDV/r showed to be less effective and more toxic than LPV/RTV as first-line HAART.

Chemokine mRNA levels in mononucleated cells of HIV-infected patients before and after initiation of PI- versus NNRTI-containing HAART

To compare CC chemokine mRNA levels from native peripheral blood mononucleated cells (PBMCs) before and 6 months after the initiation of two different regimens of highly active antiretroviral therapy (HAART), we treated group 1 (n = 11) with two nucleoside analogues and the protease inhibitor (PI) indinavir boosted by ritonavir (800/100 mg b.i.d.); group 2 (n = 8) was treated with the non-nucleoside reverse transcriptase inhibitor (NNRTI) efavirenz instead of PI. CC chemokine mRNA levels (regulated upon T cell activation expressed secreted [RANTES], macrophage inhibitory protein [MIP]-1alpha, MIP-1beta, monocyte chemotactic protein [MCP]-1, MCP-2) were quantified from PBMCs before and 6 months after the initiation of HAART using a reverse transcription/real-time polymerase chain reaction (PCR) assay. The mRNA levels of MCP-1 and MCP-2 were significantly decreased in both groups (P < 0.05), while MIP-1alpha and MIP-1beta were decreased significantly only in the PI-treated group, but not in the NNRTI group. A moderate decrease of RANTES was observed in both treatment groups. The data suggest that HAART regimens containing either NNRTI or PI are not equivalent with regard to modification of CC chemokine mRNA profiles.

Virological and immunological outcomes in HIV-1-infected Chinese patients treated with a combination of Efavirenz and Indinavir for 48 weeks

BACKGROUND

The incidence of HIV-1-related infection diseases and the mortality of AIDS have dramatically decreased since highly active antiretroviral therapy began to be used clinically in China in 1999. And we initiated a second clinical trial using a combination of Efavirenz and Indinavir to observe the effects of the immunoreaction.

METHODS

Twenty patients with laboratory-confirmed chronic HIV-1 infection were recruited. Blood samples were collected initially and during the weeks after initiation of treatment. Within 48 hours of blood sampling, peripheral blood plasma and mononuclear cells were separated using routine methods. HIV-1 viral load was measured in thawed plasma samples. Within 48 hours of peripheral blood sampling, CD4(+) and CD8(+) T cell subsets were enumerated.

RESULTS

The drug regimen was efficient in reducing HIV-1 plasma viral load and increasing total CD4(+) T cell counts. The percentage of CD4(+) and CD8(+) T cell subsets expressing CD38 and HLA-DR activation markers was positively correlated with plasma viral load and tended to normalize.

CONCLUSIONS

The combination of Efavirenz and Indinavir was generally well tolerated and efficient at reducing HIV-1 RNA. Furthermore, the treatment improved the immunological function.

Pharmacokinetics of indinavir and nelfinavir in treatment-naive, human immunodeficiency virus-infected subjects

AIDS Clinical Trials Group protocol 388 was designed to compare a three-drug regimen (indinavir with dual nucleosides) to a four-drug regimen (indinavir plus nelfinavir or indinavir plus efavirenz with dual nucleosides). Blood samples from patients taking indinavir and nelfinavir were collected over 8 to 12 h following a specified dose and were analyzed with high-performance liquid chromatography. Pharmacokinetic data were derived by using noncompartmental analysis. Following administration of indinavir every 8 h in the absence of nelfinavir (n = 8), the median predose indinavir concentration (C(0)) was 369 ng/ml (range, <10 to 949 ng/ml; one subject had a concentration of <10 ng/ml), and the concentration 8 h after administration of the study dose was 159 ng/ml (range, 85 to 506 ng/ml). In the group receiving 1000 mg of indinavir every 12 h with nelfinavir (n = 10), the median indinavir C(0) was <10 ng/ml (range, <10 to 3740 ng/ml; six subjects had a value of <10 ng/ml), and the C(12 h) was 44 ng/ml (range, <10 to 4236 ng/ml; five subjects had a value of <10 ng/ml), while the subjects who received 1200 mg of indinavir every 12 h with nelfinavir (n = 7) had a C(0) of 146 ng/ml (range, 58 to 5215 ng/ml) and a C(12 h) of 95 ng/ml (range, 12 to 954 ng/ml). Indinavir clearance was significantly lower in the presence of nelfinavir (median [interquartile range], 34.1 liters/h [range, 22.6 to 45.8 liters/h] versus 47.9 liters/h [range, 42.7 to 70.3 liters/h]; P < 0.017). For subjects receiving 1,000 mg of indinavir every 12 h, the median C(0) value for nelfinavir (n = 9) was 1,779 ng/ml (range, <187.5 to 4579 ng/ml), and the C(12 h) was 1554 ng/ml (range, <187.5 to 5,540 ng/ml). Due to the unacceptable number of undetectable indinavir trough concentrations, 1200 mg of indinavir appears to be the preferred dose in a twice-daily regimen that includes nelfinavir.

No clinically significant pharmacokinetic interactions between voriconazole and indinavir in healthy volunteers

AIMS

Voriconazole is a new triazole antifungal agent, and is metabolized by the cytochrome P450 isoenzymes CYP2C9, CYP2C19 and to a lesser extent by CYP3A4. Protease inhibitors, such as indinavir, are also metabolized by cytochrome P450 (mainly CYP3A4). As these drugs are likely to be coadministered, these studies were performed to assess the pharmacokinetic interactions, safety and toleration of these drugs when taken together.

METHODS

Two randomized placebo-controlled studies were conducted in healthy male volunteers. Study A was an open parallel-group study of the effect of indinavir on the steady-state pharmacokinetics of voriconazole in 18 volunteers (nine subjects in each group). Subjects received voriconazole 200 mg twice daily (days 1-7), then voriconazole 200 mg twice daily + indinavir 800 mg or placebo three times daily (days 8-17). Study B was a double-blind, randomized, two-way crossover study of the effect of voriconazole on the steady-state pharmacokinetics of indinavir in 14 volunteers. They received indinavir 800 mg three times daily + voriconazole 200 mg or placebo twice daily for two 7-day treatment periods separated by a washout period of at least 7 days. Pharmacokinetic parameters were compared within treatment groups at days 7 and 17 in Study A and between treatment groups on day 7 of each period in Study B. All adverse events were recorded.

RESULTS

Study A: Seventeen subjects were evaluable for pharmacokinetic analysis (eight voriconazole + indinavir, nine voriconazole + placebo). The day 17/day 7 ratios for Cmax and AUCtau were estimated as 102%[90% confidence interval (CI) 91, 114] and 107% (90% CI 98, 118), respectively. Study B: Fourteen subjects were evaluable for pharmacokinetic analysis in each treatment period. The ratios between the geometric means for indinavir + voriconazole vs. indinavir + placebo were: Cmax, 91% (90% CI 83, 101), AUCtau, 87% (90% CI 77, 100), and Cmin, 101% (90% CI 82, 125). Trough plasma concentrations of indinavir were above the concentration required to inhibit HIV replication (IC95) in both treatment periods. Voriconazole coadministered with indinavir was well tolerated in both studies.

CONCLUSIONS

The coadministration of voriconazole and indinavir in healthy volunteers had no clinically significant effect on the pharmacokinetics of either voriconazole or indinavir.

HAART Drugs Induce Oxidative Stress in Human Endothelial Cells and Increase Endothelial Recruitment of Mononuclear Cells: Exacerbation by Inflammatory Cytokines and Amelioration by Antioxidants

Highly active antiretroviral therapy (HAART) has significantly improved the prognosis of HIV-1-infected patients but is associated with significant side effects such as diabetes, atherosclerosis, and cardiovascular complications. Oxidative stress can disrupt endothelial homeostasis by dysregulating the balance between pro- and antiatherogenic factors. We hypothesized that chronic exposure to HAART results in endothelial oxidative stress and activation of mononuclear cell recruitment, an early event in atherosclerosis. We studied the effects of HAART drug combinations, consisting of zidovudine, a nucleoside reverse transcriptase inhibitor; efavirenz, a nonnucleoside reverse transcriptase inhibitor; and either of the two protease inhibitors (PIs), indinavir or nelfinavir, on human aortic endothelial cells (HAECs) by monitoring the following parameters: (1) generation of reactive oxygen species (ROS), (2) mono-nuclear cell (Jurkat or U-937) adhesion, and (3) expression of cell adhesion molecules (CAMs). HAART exposure increased ROS formation in HAECs. Exposure to PIs alone and in HAART combinations increased mononuclear cell adhesion to HAECs in a concentration-dependent manner. Mononuclear cell adhesion to HAART-exposed HAECs was significantly enhanced following acute (24-h) exposure to the inflammatory cytokines, tumor necrosis factor (TNF)-alpha or interleukin (IL)-1beta and was suppressed by the antioxidants N-ace-tylcysteine and glutathione. Exposure to HAART increased intercellular adhesion molecule-1 (ICAM-1) gene expression and concomitant exposure to TNF-alpha further increased ICAM-1, vascular cell adhesion molecule-1 (VCAM-1), and endothelial-leukocyte adhesion molecule cell surface protein levels. These studies indicate that chronic HAART exposure increases oxidative stress in endothelial cells and induces mononuclear cell recruitment, which may eventually precipitate the cardiovascular diseases observed in HIV-1+ individuals on antiretroviral therapy.

Effects of HIV Drug Combinations on Endothelin-1 and Vascular Cell Proliferation

Pulmonary arterial hypertension (PAH) is a progressive disease of the pulmonary vasculature involving endothelial and vascular smooth muscle cell (VSMC) proliferation, vasoconstriction, right ventricular hypertrophy, and eventually, right heart failure and death. PAH occurs 1000-fold more frequently in HIV patients than in the general population. Although conventional HIV therapy with nucleoside reverse transcriptase inhibitors (NRTIs) leads to regression of PAH, highly active antiretroviral therapy (HAART; two NRTI plus a protease inhibitor) increases the incidence of HIV-associated PAH as much as twofold. Although there are relatively few models for PAH, previous reports indicate the disease can be initiated by endothelial injury and release of the mitogen endothelin-1 (ET-1). ET-1, in turn, stimulates VSMC proliferation. To determine whether HAART induces endothelial injury and release of cytokines like ET-1, we treated human umbilical vein endothelial cells with micromolar amounts of AZT (3'-azido-3'-deoxythymidine), the protease inhibitor indinavir, or AZT plus indinavir, and measured cell viability, mitochondrial function, and ET-1 release. Both AZT and indinavir induced marked decreases in cellular oxygen uptake, as well as increases in ET-1 release. Although the drugs had no apparent effect on proliferation in VSMCs alone, in cocultures of VSMCs plus endothelial cells, the drugs increased proliferation of both endothelial cells and VSMCs. Finally, when cocultures of endothelial cells and VSMCs were treated with BQ-123 and BQ-788, selective antagonists for ET(A) and ET(B) receptors, respectively, drug-induced proliferation of both VSMCs and endothelial cells was attenuated. These data thus suggest that HIV drug cocktails may exacerbate preexisting HIV-associated PAH by inducing endothelial mitochondrial dysfunction, in turn stimulating the release of ET-1, and ultimately, vascular cell proliferation.

Efficacy and safety of ritonavir/indinavir 100/400 mg twice daily in combination with two nucleoside analogues in antiretroviral treatment-naive HIV-infected individuals

OBJECTIVE

To evaluate the efficacy and tolerability of indinavir/ritonavir (IDV/RTV) 400/100 mg twice daily in combination with two nucleoside reverse transcriptase inhibitors in antiretroviral-naive patients.

DESIGN AND METHODS

Antiviral therapy-naive patients with plasma HIV-1 RNA > 5000 copies/ml were enrolled in this pilot, single-arm study. CD4 cell count and viral load were evaluated at weeks (W) 4, 12, 24 and every 3 months until W48. The primary end-point was the percentage (%) of patients with viral load < 400 copies/ml at W48. Intent-to-treat (ITT) (missing values or change in treatment equalled failure) and on-treatment (OT) analyses were performed.

RESULTS

Forty patients were enrolled. Baseline median viral load was 5.36 log10 copies/ml, median CD4 count was 84 cells/mm3. At W48 by ITT analysis, the % patients with viral load < 400 copies/ml was 65% (95% CI: 48-79) and 50% (95% CI: 35-65) with viral load < 50 copies/ml, and 96% (26/27) (95% CI: 89-100) and 74% (95% CI: 57-91], respectively, by OT analysis. The median decrease in viral load at W48 was -3.83 log10 copies/ml (-0.1; -5.19) and the median increase in CD4 was +167 cells/mm3 (6-474 cell/mm3). At W4 (34/40), the median IDV C(min) was 500 ng/ml (range 5-8100) with 91% of patients with an adequate IDV C(min) > 150 ng/ml. Ten patients discontinued the study treatment before W48: adverse events (eight), patient's will (one) and simplification of therapy (one). Three patients were lost to follow-up. Only one virological failure occurred and was associated with poor compliance and sub-optimal concentrations of IDV/RTV.

CONCLUSIONS

IDV/RTV 400/100 mg twice daily is an effective and safe first-line antiretroviral therapy. The simplicity and the low cost of IDV/RTV is of major interest particularly in countries with limited resources.

Lipid–Drug Association Enhanced HIV-1 Protease Inhibitor Indinavir Localization in Lymphoid Tissues and Viral Load Reduction: A Proof of Concept Study in HIV-2287-Infected Macaques

Analysis of indinavir levels in HIV-positive patients indicated that drug concentrations in lymph node mononuclear cells (LNMCs) were about 25-35% of mononuclear cells in blood. To enhance lymphatic delivery of anti-HIV drugs, a novel drug delivery strategy was designed consisting of lipid-associated indinavir (50-80 nm in diameter) complexes in suspension for subcutaneous (SC) injection. Due to the pH-dependent lipophilicity of indinavir, practically all the drug molecules are incorporated into lipid phase when formulated at pH 7.4 and 5:1 lipid-to-drug (m/m) ratio. At pH 5.5, about 20% of drugs were found in lipid-drug complexes. Effects of lipid association on the time course of plasma indinavir concentrations were determined in macaques (Macaca nemestrina) administered with either soluble or lipid-associated formulation of indinavir (10 mg/kg, SC). Results yielded about a 10-fold reduction in peak plasma concentration and a 6-fold enhancement in terminal half-life (t1/2beta = 12 vs. 2 hours). In addition, indinavir concentrations in both peripheral and visceral lymph nodes were 250-2270% higher than plasma (compared with <35% with soluble lipid-free drug administration in humans). Administration of lipid-associated indinavir (20 mg/kg daily) to HIV-2287-infected macaques (at 30-33 weeks after infection) resulted in significantly reduced viral RNA load and increased CD4 T cell number concentrations. Collectively, these data indicate that lipid association greatly enhances delivery of the anti-HIV drug indinavir to lymph nodes at levels that cannot be achieved with soluble drug, provides significant virus load reduction, and could potentially reverse CD4 T cell depletion due to HIV infection.

Resolution of HCV infection in a HIV-infected patient under HAART after several hepatitis flare-ups

Highly active antiretroviral therapy (HAART) has been shown to have a beneficial effect on several opportunistic and other coinfections of HIV infected individuals. The effect of HAART on HCV coinfections is controversial. We describe the case of a patient, in whom a close temporal relationship between changes in HIV viremia, HCV viremia and ALT levels was observed. Longterm suppression of HIV replication by HAART was associated with a normalization of ALT levels and finally clearance of the HCV infection. Our data suggest that improved immune functions due to reductions of the HIV load led to a better control and finally resolution of the HCV infection in this patient.

Productive infection maintains a dynamic steady state of residual viremia in human immunodeficiency virus type 1-infected persons treated with suppressive antiretroviral therapy for five years

To provide insight into the dynamics and source of residual viremia in human immunodeficiency virus (HIV) patients successfully treated with antiretroviral therapy, 14 intensely monitored patients treated with indinavir and efavirenz sustaining HIV RNA at <50 copies/ml for >5 years were studied. Abacavir was added to the regimen of eight patients at year 5. After the first 9 months of therapy, HIV RNA levels had reached a plateau ("residual viremia") that persisted for over 5 years. Levels of residual viremia differed among patients and ranged from 3.2 to 23 HIV RNA copies/ml. Baseline HIV DNA was the only significant pretreatment predictor of residual viremia in regression models including baseline HIV RNA, CD4 count, and patient age. In the four of five patients with detectable viremia who added abacavir to their regimen after 5 years, HIV RNA levels declined rapidly. The estimated half-life of infected cells was 6.7 days. Decrease in activated memory cells and a reduction in gamma interferon production to HIV Gag and p24 antigen in ELISpot assays were observed, consistent with a decrease in HIV replication. Thus, in patients treated with efavirenz plus indinavir, levels of residual viremia were established by 9 months, were predicted by baseline proviral DNA, and remained constant for 5 years. Even after years of highly suppressive therapy, HIV RNA levels declined rapidly after the addition of abacavir, suggesting that productive infection contributes to residual ongoing viremia and can be inhibited with therapy intensification.

A once-daily HAART regimen containing indinavir + ritonavir plus one or two nucleoside reverse transcriptase inhibitors (PIPO study)

INTRODUCTION

There is an increased interest in developing once-daily regimens for the treatment of HIV-infected patients. A Phase II study was conducted to investigate the pharmacokinetics, and short-term safety and efficacy of an indinavir/ritonavir combination as part of a once-daily regimen.

METHODS

HIV-infected patients with either proven poor compliance to HAART regimens in the past or an anticipated poor compliance to such a regimen in the future were eligible for this study. They received a once-daily regimen consisting of indinavir 1200 mg, ritonavir 400 mg, and one or two nucleoside reverse transcriptase inhibitors (NRTIs), also administered once daily with food. A 24 h pharmacokinetic profile was constructed in a subset of patients. Short-term safety and efficacy were evaluated at 4, 12 and 24 weeks after initiation of treatment.

RESULTS

A total of 64 patients were included in this study, of whom 27 (42.2%) were treatment-naive. The geometric mean (+95% CI) of indinavir AUC0-24h, Cmax and Cmin as determined in an unselected group of 16 patients were 84.9 (69.7-103.5) mg/l x h, 12.0 (10.2-14.1) mg/l and 0.15 (0.09-0.26) mg/l, respectively. A large interpatient variability was observed, with five out of the 16 subjects having a Cmin value below the minimum effective concentration of 0.10 mg/l. During the 24 weeks of follow-up nine patients (14.1%) discontinued study medication, two due to medication-related toxicity. Gastrointestinal adverse events were reported most frequently (50.0%), followed by skin effects (45.3%), joint pain (9.4%) and urological complaints (7.8%). No patient developed nephrolithiasis. The median (+interquartile range) serum creatinine level in the 64 patients increased slightly from 74 (63-88) micromol/l to 79 (66-92) micromol/l during the 24 weeks of follow-up. One new patient reached a grade 1 elevation in serum creatinine, which normalized during the follow-up; five other patients with elevated serum creatinine at baseline remained stable. During the 24 weeks of follow-up, the proportion of patients with a viral load <500 copies/ml increased from 35.1% at baseline to 71.4% (ITT NC=F analysis) or 83.3% (OT analysis), and from 0% at baseline to 76.2% (ITT NC=F analysis) or 100.0% (OT analysis) in treatment-experienced and -naive patients, respectively. This was accompanied by a mean increase in CD4 cell count of 52 and 220 cells/mm3 in these two sub-groups, respectively.

CONCLUSION

The 24-week follow-up data of this study indicate favourable pharmacokinetics of an indinavir/ritonavir 1200/400 mg combination as part of a once-daily regimen consisting also of one or two NRTIs. Short-term safety and efficacy were also satisfactory. Long-term follow up is planned to evaluate the durability of these results.

A randomized trial of 2 different 4-drug antiretroviral regimens versus a 3-drug regimen, in advanced human immunodeficiency virus disease

To compare long-term virologic benefits of antiretroviral regimens in persons with advanced human immunodeficiency virus (HIV) disease, a randomized, open-label study was conducted of 517 subjects with no or limited previous experience with antiretroviral therapy. Subjects received lamivudine plus zidovudine and indinavir (indinavir group), efavirenz plus indinavir (efavirenz + indinavir group), or nelfinavir plus indinavir (nelfinavir + indinavir group) and were monitored for 2.1 years. Virologic failure was lower in the efavirenz + indinavir group (P=.04) and higher in the nelfinavir + indinavir group (P=.006), compared with that in the indinavir group. No difference in grade 3 or 4 adverse event rates in the efavirenz + indinavir group (P=.97) and a trend toward an increased rate in the nelfinavir + indinavir group (P=.07), compared with the indinavir group, were noted. A 4-drug regimen containing efavirenz plus indinavir resulted in a superior virologic response, whereas one containing nelfinavir plus indinavir resulted in an inferior response and a greater likelihood of toxicity.

Randomized trial to evaluate indinavir/ritonavir versus saquinavir/ritonavir in human immunodeficiency virus type 1-infected patients: the MaxCmin1 Trial

This trial assessed the rate of virological failure at 48 weeks in adult human immunodeficiency virus (HIV) type 1-infected patients assigned indinavir/ritonavir (Idv/Rtv; 800/100 mg 2 times daily) or saquinavir/ritonavir (Sqv/Rtv; 1000/100 mg 2 times daily) in an open-label, randomized (1:1), multicenter, phase 4 design. Three hundred six patients began the assigned treatment. At 48 weeks, virological failure was seen in 43 (27%) of 158 and 37 (25%) of 148 patients in the Idv/Rtv and Sqv/Rtv arms, respectively. The time to virological failure did not differ between study arms (P=.76). When switching from randomized treatment was counted as failure, this was seen in 78 of 158 patients in the Idv/Rtv arm, versus 51 of 148 patients in the Sqv/Rtv arm (P=.009). A switch from the randomized treatment occurred in 64 (41%) of 158 patients in the Idv/Rtv arm, versus 40 (27%) of 148 patients in the Sqv/Rtv arm (P=.013). Sixty-four percent of the switches occurred because of adverse events. A greater number of treatment-limiting adverse events were observed in the Idv/Rtv arm, relative to the Sqv/Rtv arm. In conclusion, Rtv-boosed Sqv and Idv were found to have comparable antiretroviral effects in the doses studied.

Administration of indinavir and low-dose ritonavir (800/100 mg twice daily) with food reduces nephrotoxic peak plasma levels of indinavir

BACKGROUND

The objective of this study was to compare indinavir peak plasma (Cmax) values after administration of indinavir/ritonavir 800/100 mg on an empty stomach or with food. High indinavir Cmax values have been associated with indinavir-related nephrotoxicity.

METHODS

This was an open-label, randomized, two-treatment, two-period, cross-over pharmacokinetic study performed at steady state. HIV-infected patients who had been using indinavir/ritonavir 800/100 mg twice daily for at least 4 weeks were randomized to take this combination with a light breakfast (two filled rolls and 130 ml of fluid) on a first study day, and without food on a second day, or in the reverse order. The pharmacokinetics of indinavir and ritonavir were assessed after plasma and urine sampling during 12 h.

RESULTS

Data for nine patients were evaluated. Administration of indinavir/ritonavir 800/100 mg on an empty stomach resulted in a higher indinavir Cmax [geometric mean (GM) ratio - fasting/fed and 95% confidence interval (CI): 1.28 (1.08-1.52), P=0.01] and a trend to a shorter indinavir tmax (P=0.07) compared to administration with food. The mode of administration of indinavir/ritonavir did not affect plasma indinavir Cmax and AUC values, parameters that have been associated with the antiviral efficacy of indinavir, nor the urinary excretion of indinavir.

CONCLUSIONS

Administration of indinavir/ritonavir 800/100 mg on an empty stomach results in a higher indinavir Cmax compared to ingestion with a light meal. Stated the other way round, intake with a light meal reduces indinavir Cmax, which probably reflects a food-induced delay in the absorption of indinavir. It is recommended to administer indinavir/ritonavir 800/100 mg with food, as a possible means to prevent indinavir-related nephrotoxicity in patients who start or continue with this regimen.

Indinavir, efavirenz, and abacavir pharmacokinetics in human immunodeficiency virus-infected subjects

Adult AIDS Clinical Trials Group (AACTG) Protocol 886 examined the dispositions of indinavir, efavirenz, and abacavir in human immunodeficiency virus-infected subjects who received indinavir at 1,000 mg every 8 h (q8h) and efavirenz at 600 mg q24h or indinavir at 1,200 mg and efavirenz at 300 mg q12h with or without abacavir 300 at mg q12h. Thirty-six subjects participated. The median minimum concentration in plasma (C(min)) for indinavir administered at 1,200 mg q12h was 88.1 nM (interquartile range [IR], 61.7 to 116.5 nM), whereas the median C(min) for indinavir administered at 1,000 mg q8h was 139.3 nM (IR, 68.8 to 308.7 nM) (P = 0.19). Compared to the minimum C(min) range for wild-type virus (80 to 120 ng/ml) estimated by the AACTG Adult Pharmacology Committee, the C(min) for indinavir administered at 1,200 mg q12h (54 ng/ml) is inadequate. The apparent oral clearance (CL/F) (P = 0.28), apparent volume of distribution at steady state (V(ss)/F) (P = 0.25), and half-life (t(1/2)) (P = 0.80) of indinavir did not differ between regimens. The levels of efavirenz exposure were similar between regimens. For efavirenz administered at 600 mg q24h and 300 mg q12h, the median maximum concentrations in plasma (C(max)s) were 8,968 nM (IR, 5,784 to 11,768 nM) and 8,317 nM (6,587 to 10,239 nM), respectively (P = 0.66), and the C(min)s were 4,289 nM (IR, 2,462 to 5,904 nM) and 4,757 nM (IR, 3,088 to 6,644 nM), respectively (P = 0.29). Efavirenz pharmacokinetic parameters such as CL/F (P = 0.62), V(ss)/F (P = 0.33), and t(1/2) (P = 0.37) were similar regardless of the dosing regimen. The median C(max), C(min), CL/F, V(ss)/F, and t(1/2) for abacavir were 6,852 nM (IR, 5,702 to 7,532), 21.0 nM (IR, 21.0 to 87.5), 43.7 liters/h (IR, 37.9 to 55.2), 153.9 liters (IR, 79.6 to 164.4), and 2.0 h (IR, 1.8 to 2.8), respectively. In summary, when indinavir was given with efavirenz, the trough concentration of indinavir after administration of 1,200 mg q12h was inadequate. Abacavir did not influence the pharmacokinetics or exposure parameters of either indinavir or efavirenz. The levels of efavirenz exposure were similar in subjects receiving efavirenz q12h or q24h.

[Observational study on the efficacy of the application of two classical regimens of triple antiretroviral therapy]

BACKGROUND

To compare the temporal evolution of viral load and CD4 parameters in two cohorts of HIV infected patients enrolled in classical triple antiretroviral regimens.

METHODS

Retrospective, observational, descriptive study of the proportions of patients reaching undetectable levels of viral load (VL) as well as the time necessary to get it. The two cohorts were as follows: 91 HIV patients on triple therapy with zidovudine plus lamivudine and indinavir (cohort A) versus 80 HIV patients with Stavudine plus Didanosine and Indinavir (cohort B).

RESULTS

The evolution of the patients in terms of percentages who reach undetectable VL was similar in the two therapeutic cohorts (75.8%for cohort A vs 73.8% for cohort B) along the duration of the study (four years). However, the mean time period needed to reach undetectable VL was different, 209 days (IC 95% 175-243 days) for patients in zidovudine plus lamivudine and indinavir and 330 days (IC 95% 263-396 days) for stavudine plus didanosine and indinavir regimen. The immunological status observed in the patients when reaching his first undetectable VL was significantly different. The proportion of patients with CD4 cells counts >200/mm3 in cohort A was 83.1% while for patients from cohort B was 65.4% (p=0.032).

CONCLUSIONS

This observational study from clinical settings seems demonstrate similar efficacy to reach undetectable VL with both classical triple antiretroviral therapies evaluated but a shorter delay of time to reach that virological situation for zidovudine plus lamivudine and indinavir regimen is reported.