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Interaction of anti-HIV protease inhibitors with the multidrug transporter P-glycoprotein (P-gp) in human cultured cells.

The anti-HIV protease inhibitors represent a new class of agents for treatment of HIV infection. Saquinavir, ritonavir, indinavir, and nelfinavir are the first drugs approved in this class and significantly reduce HIV RNA copy number with minimal adverse effects. They are all substrates of cytochrome P450 3A4, and are incompletely bioavailable. The drug transporting protein, P-glycoprotein (P-gp), which is highly expressed in the intestinal mucosa, could be responsible for the low oral bioavailability of these and other drugs which are substrates for this transporter. To determine whether these protease inhibitors are modulators of P-gp, we studied them in cell lines which do and do not express P-gp. Saquinavir, ritonavir and nelfinavir significantly inhibited the efflux of [3H]paclitaxel and [3H]vinblastine in P-gp-positive cells, resulting in an increase in intracellular accumulation of these drugs. However, similar concentrations of indinavir did not affect the accumulation of these anticancer agents. In photoaffinity labeling studies, saquinavir and ritonavir displaced [3H]azidopine, a substrate for P-gp, in a dose-dependent manner. These data suggest that saquinavir, ritonavir, and nelfinavir are inhibitors and possibly substrates of P-gp. Because saquinavir has a low bioavailability, its interaction with P-gp may be involved in limiting its absorption.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Incidence of adverse reactions in HIV patients treated with protease inhibitors: a cohort study. Coordinamento Italiano Studio Allergia e Infezione da HIV (CISAI) Group.

OBJECTIVE: To assess the probability that protease inhibitor (PI) therapy might be discontinued because of adverse events (AE) and to evaluate the incidence rate of adverse reactions during PI treatment. DESIGN: A prospective cohort, multicenter study on HIV-positive patients starting treatment with at least one PI. SETTING: Ten departments of infectious diseases in Northern Italy. PATIENTS: A total of 1207 patients who started PI therapy in September 1997 and were consecutively observed up to April 1999. MAIN OUTCOME MEASURES: Adverse reactions following initiation of PI therapy, and time to therapy discontinuation due to AE. RESULTS: During the study period, 35.9% patients presented adverse reactions of any grade, whereas 9.7% presented at least one serious AE. After 12 months of treatment, the percentage of patients who had interrupted treatment was 36% of ritonavir-treated patients, 14.2% of those treated with indinavir, 13.6% of ritonavir-saquinavir hard gel capsules (HGC)-treated patients, and 8.5% and 2.1%, respectively, for those treated with nelfinavir and saquinavir HGC. Women and patients with hepatitis experienced a significantly greater number of adverse events compared with other categories. Gastrointestinal events were more frequently observed in patients treated with either ritonavir alone or in combination with saquinavir HGC, as well as in patients receiving nelfinavir, although in this group serious events were rare. Here again, neurologic, metabolic, and hepatic toxicity occurred more frequently in ritonavir and ritonavir-saquinavir HGC treated patients. Allergic reactions were more often observed in patients receiving nelfinavir. Indinavir-treated patients presented the highest incidence of renal toxicity. CONCLUSION: Ritonavir is the drug associated with the largest number of reactions, which appear during the first few months of treatment. Saquinavir HGC and nelfinavir are the best tolerated drugs in a clinical setting.

Adult↗

Patient-reported nonadherence to HAART is related to protease inhibitor levels.

OBJECTIVE: To compare self-reported nonadherence with antiretroviral therapy (ART) with predose plasma levels of protease inhibitor (PI). DESIGN: A cross-sectional study of consecutive patients from a university-based HIV clinic in Rome, Italy, was conducted. One hundred and forty HIV-infected patients were prescribed regimens containing ritonavir or indinavir. A patient questionnaire assessing knowledge of treatment regimen, adherence behavior, reasons for taking and missing therapy, factors influencing adherence, and health behaviors was administered. A predose PI plasma level was measured concurrently. RESULTS: By patient report, 12% missed at least one dose "yesterday," and 24% missed doses in the last 3 days; 14% had a predose plasma concentration below the assay limit of quantitation (2 ritonavir and 18 indinavir samples). Confusion, poor psychological well-being, long office wait, running out of drugs between visits, having relatives to remind the patient to take medication, children, and alteration of sense of taste were related to unquantifiable predose levels of PI. In multivariable analysis, reported nonadherence (odds ratio [OR], 15.8; 95% confidence interval [CI], 4.0-63.3) and confusion (OR, 9.9; 95% CI, 1.4-69.6) were related to unquantifiable predose levels of PI. CONCLUSION: Self-report of missing a dose of antiretroviral medication "yesterday" was related to an unmeasurable plasma PI level.

Adult↗

HIV-protease inhibitors contribute to P-glycoprotein efflux function defect in peripheral blood lymphocytes from HIV-positive patients receiving HAART.

P-glycoprotein (P-gp) has been found expressed in normal human cells, such as bone marrow and peripheral blood cells. The aim of this study was to investigate whether HIV-protease inhibitors (HIV-PIs) interact with P-gp efflux function in normal human peripheral blood lymphocytes (PBLs) and CD34+ progenitor cells. Moreover, we analyzed the in vivo effect of HIV-PIs on P-gp function in PBLs from HIV-infected patients receiving highly active antiretroviral therapy (HAART). We found that HIV-PIs (i.e., ritonavir, saquinavir, nelfinavir and indinavir) interfere with P-gp function in normal PBLs as demonstrated by the reduced efflux of rhodamine 123 (Rh123). This effect was dose-dependent and suggested the following hierarchy: ritonavir > saquinavir > nelfinavir > indinavir. We further analyzed the effect of HIV-PIs on the P-gp function in specific PBLs subsets. Our results show an HIV-PI-induced inhibition of P-gp function in CD4+ and CD8+ T cell subsets, mostly caused by the effect on the naive compartment of both CD4+ and CD8+ T cells. The same inhibitory effect was found in CD34+ hematopoietic progenitor cells. With respect to the in vivo evaluation of P-gp function in PBLs from HIV-infected patients, we found reduced levels of Rh123 efflux that reached the lowest value in AIDS patients receiving HAART. We concluded that HIV-PIs interfere with P-gp function in major cellular targets for HIV infection, such as CD4+ T cells and CD34+ progenitor cells. This ability may contribute to P-gp efflux function defect found in HIV-infected patients and suggests that drug interaction studies are crucial to an overall understanding of the effects of this important group of drugs.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Differential effect of HIV protease inhibitors on adipogenesis: intracellular ritonavir is not sufficient to inhibit differentiation.

OBJECTIVES: Lipodystrophy is a major side effect of HIV protease inhibitor (PI) antiretroviral therapy. It has been shown that protease inhibitors interfere in vitro with adipocyte differentiation. However, there is no evidence that PIs accumulate into preadipocytes and adipocytes and that intra-cellular accumulation is sufficient to alter differentiation. We assessed the effect of six different PIs on the differentiation of cells from four clonal lines. We also studied the capacity of ritonavir to accumulate both into drug-sensitive and drug-resistant cultured adipocytes. METHODS: Adipocyte differentiation of mouse 3T3-F442A, 3T3-L1 and Ob1771 cells as well as embryonic stem cells were investigated at pharmacological concentrations of indinavir, saquinavir, ritonavir, amprenavir, nelfinavir and lopinavir. We used a sensitive ELISA to determine intracellular concentration of ritonavir from 3T3-L1 and Ob1771 preadipocytes. RESULTS: Nelfinavir and lopinavir inhibited adipocyte differentiation whereas amprenavir was ineffective. Indinavir, saquinavir and ritonavir inhibited differentiation of 3T3-L1 and 3T3-F442A cells but did not alter differentiation of either Ob1771 or embryonic stem cells. We showed that ritonavir accumulated in preadipocytes and fully differentiated 3T3-L1 adipocytes as a function of its extracellular concentration. Although Ob1771 cells were resistant and 3T3-L1 cells were sensitive to ritonavir, the drug accumulated to similar levels in both cases. CONCLUSIONS: Protease inhibitors inhibit adipocyte differentiation depending on the cell model used. We showed for the first time that ritonavir accumulates into preadipocytes and adipocytes, suggesting a direct effect on intracellular targets. However, intracellular accumulation was clearly not sufficient as Ob1771 cells remained resistant to the inhibitory effect of ritonavir.

3T3 Cells↗

Risk factors and occurrence of rash in HIV-positive patients not receiving nonnucleoside reverse transcriptase inhibitor: data from a randomized study evaluating use of protease inhibitors in nucleoside-experienced patients with very low CD4 levels (<50 cells/microL).

BACKGROUND: Most of the studies evaluating rash in HIV-positive patients have focused on nonnucleoside reverse transcriptase inhibitors (NNRTI), particularly nevirapine, and little is known about the occurrence of rash and the risk factors for its development in patients receiving regimens not based on NNRTI. METHODS: We evaluated all cases of rash observed during a 48-week randomized multicentre trial in 1251 nucleoside-experienced patients who started treatment with protease inhibitors (ritonavir or indinavir) at CD4 counts below 50 cells/microL. Incidence rates for rash were calculated according to gender, clinical status, age, use of highly active antiretroviral therapy (HAART), Pneumocystis carinii pneumonia (PCP) prophylaxis and use of individual antiretroviral drugs at enrollment. Differences between groups defined according to the above characteristics were tested for statistical significance using the log-rank test in a Kaplan-Meier survival analysis. All factors that gave results in the univariate analyses below the significance level of 0.05 were included in a multivariate analysis using a Cox regression model. RESULTS: During a follow-up period of 9690 person-months, 66 patients (5.3%) developed rash (0.68 events/100 person-months). In the univariate analyses, risk of rash did not differ with trial treatment (indinavir or ritonavir), clinical status, PCP prophylaxis, or age. During follow-up, rash was observed in 7.5% of enrolled women and in 4.5% of enrolled men (P=0.03). Serious rash occurred in 4.5% of enrolled women and in 1.6% of enrolled men (P=0.003). Use of HAART (P<0.001) and inclusion of zidovudine and of zalcitabine in the prescribed regimen (P=0.02) appeared to be associated with a lower risk of rash. In the multivariate analysis, the variables that remained significantly predictive of rash were gender (risk for women compared to men: 1.65, 95% confidence interval (CI): 1.00-2.72, P=0.048) and use of a non-HAART regimen (risk for non-HAART patients compared to HAART: 2.73, 95% CI: 1.49-5.02, P=0.001). CONCLUSIONS: In our study, about 5% of HIV-positive patients who started treatment with protease inhibitors at very low CD4 counts developed rash, generally in the first few weeks after treatment. Risk was significantly higher in women and in patients who did not receive a HAART regimen. Our data indicate that women have a higher risk of rash than men, also with regimens that do not include NNRTI.

Adult↗

HIV protease inhibitors attenuate adherence of Candida albicans to epithelial cells in vitro.

Oropharyngeal candidiasis is one of the first and most commonly reported opportunistic infections of untreated AIDS patients. With the introduction of the new antiviral HAART therapy, including HIV protease inhibitors, this mucocutaneous infection is nowadays only rarely observed in treated patients. It was recently shown that HIV protease inhibitors have a direct attenuating effect on Candida albicans secreted aspartic proteinases (Saps), an investigation prompted by the fact that both Sap and HIV protease belong to the superfamily of aspartic proteinases and by the observation that mucocutaneous infections sometimes resolve even in the absence of an immunological improvement of the host. As these Saps are important fungal virulence factors and play a key role in adhesion to human epithelial cells we tried to assess the effect of the HIV protease inhibitors Ritonavir, Indinavir and Saquinavir on fungal adhesion to these cells. The effect on phagocytosis by polymorphonuclear leukocytes was also assessed. Ritonavir was found to be the most potent inhibitor of fungal adhesion. A dose-dependent inhibition of adhesion to epithelial cells was found already at 0.8 microM and was significant at 4 microM or higher, at 500 microM the inhibition was about 55%. Indinavir and Saquinavir inhibited significantly at 4 microM or 20 microM, respectively; at 500 microM the inhibition was 30% or 50%. In contrast, no protease inhibitor was able to modulate phagocytosis of Candida by polymorphonuclear leukocytes. In conclusion, inhibition of Saps by HIV protease inhibitors may directly help to ease the resolution of mucosal candidiasis. In future, derivatives of HIV protease inhibitors, being more specific for the fungal Saps, may form an alternative in the treatment of mucosal candidiasis insensitive to currently available antimycotics.

Aspartic Acid Endopeptidases↗

HIV protease inhibitors are inhibitors but not substrates of the human breast cancer resistance protein (BCRP/ABCG2).

Breast cancer resistance protein (BCRP) is a recently discovered ATP-binding cassette drug transporter. Hence, the full spectrum of therapeutic agents that interact with BCRP remains to be elucidated. Because human immunodeficiency virus protease inhibitors (HPIs) are well known P-glycoprotein (P-gp) substrates, and there is an overlap in substrate specificity between P-gp and BCRP, this study was performed to investigate whether HPIs are substrates and/or inhibitors of BCRP. First, the effect of HPIs on BCRP efflux activity in human embryonic kidney (HEK) cells stably expressing wild-type BCRP (482R) and its two mutants (482T and 482G) was studied by measuring intracellular mitoxantrone fluorescence using flow cytometry. We found that ritonavir, saquinavir, and nelfinavir were effective inhibitors of wild-type BCRP (482R) with IC50 values of 19.5 +/- 0.8 microM, 19.5 +/- 7.6 microM, and 12.5 +/- 4.1 microM, respectively. Ritonavir, saquinavir, and nelfinavir inhibited 482T and 482G with IC50 values that were approximately 2 times greater than that for 482R. Indinavir and amprenavir had no significant inhibition on BCRP activity. Direct efflux of radiolabeled HPIs in HEK cells was measured to determine whether the HPIs are substrates of BCRP. None of the HPIs were found to be transported by BCRP. Together, ritonavir, saquinavir, nelfinavir, indinavir, and amprenavir are not substrates for BCRP. However, ritonavir, saquinavir, and nelfinavir are effective inhibitors of the transporter. These results suggest that BCRP may play an important role in drug-drug interactions involving coadministration of the HPIs with drugs that are substrates of the transporter.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

HIV protease inhibitors: suppression of insulin secretion by inhibition of voltage-dependent K+ currents and anion currents.

We have shown before that the human immunodeficiency virus (HIV) protease inhibitors ritonavir and nelfinavir, but not indinavir, suppress insulin secretion from mouse pancreatic B-cells via reduction of the cytosolic free calcium concentration ([Ca(2+)](c)). This was not because of an effect on ATP-dependent K(+) channels (K(ATP) channels) or L-type Ca(2+) channels. The study was intended to elucidate the mechanisms by which distinct HIV protease inhibitors decrease [Ca(2+)](c) and thus evoke their adverse side effect on insulin release. Membrane potential and whole-cell currents were measured with the patch-clamp technique, and [Ca(2+)](c) was determined with a fluorescence dye. Ritonavir and nelfinavir both inhibited the same component(s) of voltage-dependent K(+) currents with a concomitant change in action potential wave form, whereas indinavir was ineffective. Comparison with other blockers of voltage-dependent K(+) currents revealed that suppression of distinct noninactivating current component(s) altered action potential wave form and decreased [Ca(2+)](c) similar to ritonavir and nelfinavir, whereas blockage of inactivating component(s) was without effect. Complete inhibition of voltage-dependent K(+) currents by 80 mM TEA(+) drastically increased [Ca(2+)](c), demonstrating that voltage-dependent K(+) channels are not the sole target of ritonavir and nelfinavir. Accordingly, the Ca(2+)-lowering effect of ritonavir was preserved in the presence of 80 mM TEA(+). This effect was mimicked by the anion channel blocker 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS). Consequentially, ritonavir and nelfinavir inhibited a DIDS-sensitive anion current in B-cells. We suggest that ritonavir and nelfinavir decrease insulin secretion by inhibition of voltage-dependent K(+) channels and anion channels, which are essential to provide counterion currents for Ca(2+) influx across the plasma membrane.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

Low level of cross-resistance to amprenavir (141W94) in samples from patients pretreated with other protease inhibitors.

The therapeutic success of an antiretroviral salvage regimen containing protease inhibitors (PI) is limited by PI-resistant viral strains exhibiting various degrees of resistance and cross-resistance. To evaluate the extent of cross-resistance to the new PI amprenavir, 155 samples from 132 human immunodeficiency virus type 1-infected patients were analyzed for viral genotype by direct sequencing of the protease gene. Concomitantly, drug sensitivity to indinavir, saquinavir, ritonavir, nelfinavir, and amprenavir was analyzed by a recombinant virus assay. A total of 111 patients had been pretreated with 1-4 PI, but all were naive to amprenavir. A total of 105 samples (67.7%) were sensitive to amprenavir; 25 samples (16.1%) were intermediately resistant, and another 25 samples were highly resistant (4- to 8-fold- and >8-fold-reduced sensitivity, respectively). The mutations 46I/L, 54L/V, 84V, and 90M showed the strongest association with amprenavir resistance (P < 0. 0001). The scoring system using 84V and/or any two of a number of mutations (10I/R/V/F, 46I/L, 54L/V, and 90M) predicted amprenavir resistance with a sensitivity of 86.0% and a specificity of 81.0% within the analyzed group of samples. Of 62 samples with resistance against 4 PI, 23 (37.1%) were still sensitive to amprenavir. In comparison, only 2 of 23 samples (8.7%) from nelfinavir-naive patients with resistance against indinavir, saquinavir, and ritonavir were still sensitive to nelfinavir. Amprenavir thus appears to be an interesting alternative for PI salvage therapy.

Carbamates↗

Comparison of DNA sequencing and a line probe assay for detection of human immunodeficiency virus type 1 drug resistance mutations in patients failing highly active antiretroviral therapy.

The resistance of human immunodeficiency virus type 1 (HIV-1) to drugs is a major cause of antiretroviral treatment failure. We have compared direct sequencing to a line probe assay (LiPA) for the detection of drug resistance-related mutations in 197 clinical samples, and we have investigated the sequential appearance of mutations under drug pressure. For 26 patients with virological failure despite the use of two nucleoside analogues and one protease inhibitor (indinavir [n = 6], ritonavir [n = 10], and saquinavir [n = 10]), genotypic resistance assays were carried out retrospectively every 3 months for up to 2 years by using direct sequencing (TruGene; Visible Genetics) and a LiPA for detection of mutations in the reverse transcriptase (INNO-LiPA HIV-1 RT; Innogenetics) and the protease (INNO-LiPA HIV Protease, prototype version; Innogenetics) genes. Comparison of the results from both assays found rare major discrepancies (<1% of codons analyzed). INNO-LiPA detected more wild-type-mutant mixtures than sequencing but suffered from a high rate of codon hybridization failures for the reverse transcriptase. LiPA detected earlier and more frequently than sequencing the transient mixed virus population that contained I84V, which appears before V82A in the protease sequence. Mutations M461, G48V, and L90M were often transient and drug pressure related. In conclusion, direct sequencing and LiPAs give concordant results for most clinical isolates. LiPAs are more sensitive for the detection of mixed virus populations. Mutation I84V appears in minor populations in the early steps of the pathways of resistance to indinavir and ritonavir. The fact that some mutations can be found only transiently and in minor virus populations highlights the importance of a low detection limit for resistance assays.

Acquired Immunodeficiency Syndrome↗

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.

Acquired Immunodeficiency Syndrome↗

The HIV protease inhibitor ritonavir blocks osteoclastogenesis and function by impairing RANKL-induced signaling.

Highly active antiretroviral therapy (HAART), which includes HIV protease inhibitors (PIs), has been associated with bone demineralization. To determine if this complication reflects accelerated resorptive activity, we studied the impact of two common HIV PIs, ritonavir and indinavir, on osteoclast formation and function. Surprisingly, we find that ritonavir, but not indinavir, inhibits osteoclast differentiation in a reversible manner and also abrogates bone resorption by disrupting the osteoclast cytoskeleton, without affecting cell number. Ritonavir given in vivo completely blunts parathyroid hormone-induced osteoclastogenesis in mice, which confirms that the drug is bone sparing. In keeping with its antiresorptive properties, ritonavir impairs receptor activator of nuclear factor kappaB ligand-induced (RANKL-induced) activation of NF-kappaB and Akt signaling pathways, both critical to osteoclast formation and function. In particular, ritonavir is found to inhibit RANKL-induced Akt signaling by disrupting the recruitment of TNF receptor-associated factor 6/c-Src complex to lipid rafts. Thus, ritonavir may represent a bone-sparing PI capable of preventing development of osteopenia in patients currently on HAART.

Animals↗

Chemotherapy for human immunodeficiency virus-associated non-Hodgkin's lymphoma in combination with highly active antiretroviral therapy.

PURPOSE: This study investigated the efficacy, toxicity, and pharmacokinetic interactions resulting from simultaneous combination chemotherapy and highly active antiretroviral therapy (HAART) for patients with human immunodeficiency virus (HIV)-associated non-Hodgkin's lymphoma (NHL). In addition, the effects on viral load, CD4 counts, and opportunistic infections were examined with the use of combination chemotherapy combined with HAART. PATIENTS AND METHODS: Sixty-five patients with previously untreated and measurable disease at any stage of HIV-associated NHL of intermediate or high grade were entered onto this study at 17 different centers. The first 40 patients entered onto the study received reduced doses of cyclophosphamide and doxorubicin, combined with vincristine and prednisone (modified CHOP [mCHOP]), whereas the subsequent 25 patients entered onto the study received full doses of CHOP combined with granulocyte colony-stimulating factor (G-CSF). All patients also received stavudine, lamivudine, and indinavir. RESULTS: The complete response rates were 30% and 48% among patients who received mCHOP and full-dose CHOP combined with HAART, respectively. Grade 3 or 4 neutropenia occurred in 25% of patients receiving mCHOP and 12% of those receiving full-dose CHOP combined with G-CSF (25% v 12%). There were similar numbers of patients with grade 3 or 4 hyperbilirubinemia (12% and 17%), constipation and abdominal pain (18% and 17%), and transaminase elevation (48% and 52%) on the modified and full-dose arms of the study, respectively. Doxorubicin clearance and indinavir concentration curves were similar among patients on this study and historical controls, whereas cyclophosphamide clearance was 1.5-fold reduced as compared with control values. Human immunodeficiency virus (HIV) load declined from a median baseline value of 29,000 copies/mL to a median minimum value on therapy of 500 copies/mL. CONCLUSION: Either modified-dose or full-dose CHOP chemotherapy for HIV-NHL, delivered with HAART, is effective and tolerable.

Adult↗

Treatment with highly active antiretroviral therapy in human immunodeficiency virus type 1-infected children is associated with a sustained effect on growth.

INTRODUCTION: Growth failure is a common feature of children with human immunodeficiency virus type 1 (HIV-1) infection. Children who are treated with mono or dual nucleoside analogue reverse transcriptase inhibitor (NRTI) therapy show a temporary increase in weight gain and linear growth rate. In adults, protease-inhibitor-containing antiretroviral therapy is associated with a sustained weight gain and increased body mass index (BMI). Experience with protease inhibitors and growth in children is still limited. The data mainly deal with short-term effects on growth. OBJECTIVE: To evaluate the effect of highly active antiretroviral therapy (HAART) on growth in children with HIV-1 infection. DESIGN AND METHODS: We analyzed selected growth parameters, clinical data, and laboratory results as part of a prospective, open, uncontrolled, multicenter study to evaluate the clinical, immunologic, and virologic response to HAART consisting of indinavir, zidovudine, and lamivudine in children with HIV-1 infection. Height and weight were measured at 0, 12, 24, 36, 48, 60, 72, 84, and 96 weeks after initiation of HAART. Information about the children's growth before enrollment in the study was retrieved from the hospital medical records and/or the school doctor or health center. BMI was calculated. z Scores were used to express the standard deviation (SD) in SD units from the Dutch reference curves for age and gender. Viral loads and CD4+ T-cell counts were examined prospectively and related to these growth parameters. z Scores were also calculated for CD4+ T-cell counts to correct for age-related differences. A z score of 0 represents the P50, which is exactly the age/sex-appropriate median. A height z score of -1 indicates that a child's height is 1 SD below the age- and gender-specific median height for the normal population. Virologic responders were defined as those who either reached an undetectable viral load (<500 copies/mL) or had a >1.5 log reduction in viral load compared with baseline at week 12 after the initiation of HAART, which was maintained during the follow-up period. RESULTS. PATIENTS: Twenty-four patients were included (age: 0.4-16.3 years at baseline), with a median HIV-1 RNA load of 105 925 copies/mL (5.03 log), a median CD4+ T-cell count of 0.586 x 10(9)/L (median z score: -2.28 SD), a median height z score of -1.22, a median weight z score of -0.74, and a median baseline BMI z score of -0.32. Eleven patients were naive to antiretroviral therapy, and 13 patients had received previous treatment with NRTI monotherapy. Twenty children used indinavir and 4 children used nelfinavir as part of HAART. VIROLOGIC AND IMMUNOLOGIC RESPONSES TO HAART: Seventeen children were virologic responders, and 7 children were virologic nonresponders. In patients naive to NRTIs, median baseline viral loads were significantly higher than in pretreated patients. However, at weeks 48 and 96, there was no significant difference between the viral loads of both groups. At baseline, there was no significant difference in CD4+a T-cell z scores between virologic responders and nonresponders or between naive and pretreated patients. During 96 weeks of HAART, the increase of CD4+ T-cell z score was significantly higher in responders than in nonresponders. The increase in CD4+ T-cell z score was not significantly different for naive and pretreated patients. HEIGHT, WEIGHT, AND BMI z SCORE CHANGES: We found that there was a trend toward a significantly increased z score change during 96 weeks of HAART compared with the z score change before HAART initiation for height and weight, but not for BMI. GROWTH AND VIROLOGIC RESPONSE TO HAART: When the data were analyzed separately for virologic responders and nonresponders, virologic responders showed significant increases in height and weight. The height and weight of virologic nonresponders did not change significantly. The BMI did not change significantly in responders or in nonresponders. GROWTH AND IMMUNOLOGIC RESPONSE TO HAART: The increase of weight and BMI z scores from baseline correlated positively with the CD4+ T-cell z score increase from baseline. It did not correlate with absolute CD4+ T-cell count increase. Height z score increase did not correlate with CD4+ T-cell z score or with absolute CD4+ T-cell counts. GROWTH AND PREVIOUS NRTI TREATMENT: The height z score decrease from week -48 to baseline was significantly larger in naive than in pretreated patients. The weight and BMI z score change from week -48 to baseline was not significantly different for pretreated and naive patients. From baseline to week 96, the height and weight z score change increased significantly in naive patients but not in pretreated patients compared with the change from week -48 to baseline. The BMI z score did not change significantly over 96 weeks of HAART for naive or pretreated patients. GROWTH AND CLINICAL STAGE OF INFECTION: The clinical stage of infection according to the Centers for Disease Control and Prevention classification correlated negatively with the BMI z score and the weight z score at baseline but not with the height z score. Thus, children with the most severe clinical disease had the lowest BMI and weight z scores at baseline. The BMI z score increased more in children with more advanced clinical infection at baseline, who had lower BMI at baseline. The clinical stage of infection did not correlate with the change in weight z score from baseline to week 96. CONCLUSIONS: HAART has a positive influence effect on the growth of HIV-1-infected children. This effect is sustained for at least 96 weeks. Height and weight are favorably influenced in children in whom HAART leads to a reduction of the viral load of at least 1.5 log or to <500 copies/mL and to an increase in the CD4+ T-cell z score. In contrast to the increase of the BMI in adults on HAART, BMI did not increase in all children effectively treated with HAART. BMI increased more in children with an advanced stage of infection and a poor nutritional status at baseline. Data from pretreated and naive patients were difficult to interpret, because the baseline characteristics of these 2 groups differed too much.

Antiretroviral Therapy, Highly Active↗

[AIDS, activism, and the regulation of clinical trials in Brazil: Protocol 028].

This paper examines the politics and practices of drug evaluation in Brazil. It traces the history of AIDS activists' influence on the organization of modern clinical trials and their scientific rationale. Using the Merck indinavir trial as a case study, the authors discuss how organized civil society has developed strategies to intervene in the course of drug evaluation trials, shaping them according to its own interests. Adopting translation sociology as the theoretical framework, the paper describes and analyzes the strategies used by activists from "Grupo PelaVidda/SP" (an AIDS NGO) to build a consensus concerning indinavir monotherapy's lack of efficacy. The study considers the several regulatory forums involved in dealing with the controversy during the trial period.

Acquired Immunodeficiency Syndrome↗

Clinical efficacy of protease inhibitor based antiretroviral combination therapy--a prospective cohort study.

OBJECTIVES: To analyze virological and clinical efficacy of protease inhibitor based antiretroviral regimens in a cohort of unselected HIV-infected patients. METHODS: Prospective analysis of all HIV-infected patients started on protease inhibitor therapy until August 31, 1997 in two outpatient clinics. Partial viral suppression was defined as reduction of HIV-RNA at least 1log(10) below baseline and complete viral suppression as reduction below the limit of detection. Risk factors for clinical and virological failure were analyzed by a Cox proportional hazard model. RESULTS: 387 patients (median observation time 381 days) were analyzed. In 312 patients (81%) partial and in 265 (68%) complete viral suppression was observed. Secondary failure occurred in 75 patients and could be reversed in 11/75. The probability of virological failure at one year was 51% for complete and 47% for partial suppression. CD4-cells increased by a median of 101/microl overall and 39/microl for patients without partial virologic suppression. 57 clinical events or deaths occurred in 44 pts. Risk factors for virological failure were AIDS at baseline (RR 1.6) and use of Saquinavir vs. Indinavir or Ritonavir (RR 1.7), for clinical failure AIDS at baseline (RR 4. 9), CD4-cell count (0.74 for increase of 50/microl), degree of viral suppression (RR 0.1 for complete suppression) and PI used (Saquinavir vs. Indinavir or Ritonavir, RR 2.7). CONCLUSIONS: Virological failure of PI based combination therapy is common and associated with advanced HIV-infection. Clinical failure is associated with advanced HIV-infection and failure to suppress viral replication.

Adult↗

Induction and maintenance treatment regimens for HIV-1 infection in vitro.

Can aggressive anti-human immunodeficiency virus (HIV) induction regimens be simplified after sufficient virus suppression is achieved? In vitro studies were conducted to evaluate the hypothesis that aggressive induction regimens could be followed by less aggressive maintenance regimens. A clinical HIV-1 isolate and lymphoblastoid cell line (H9) were employed. Virus multiplicities were varied, as were drug inhibitory concentrations (IC90, IC99) and induction periods (1, 2 and 3 weeks) of a three-drug regimen (zidovudine plus lamivudine and indinavir), following which maintenance regimens (no drug, zidovudine alone, indinavir alone, zidovudine plus lamivudine) were employed. After 1 week inductions at IC99 concentrations, viral rebound occurred on none or one-drug maintenance regimens but not on a two-drug regimen. After 2 week inductions, viral rebound occurred with no-drug maintenance, but not with one- and two-drug regimens. After 3 week inductions, viral rebound did not occur in zero-, one-, or two-drug maintenance regimens, although HIV-1 DNA persisted in cultured cells. These studies suggest that although some induction-maintenance regimens will fail, after a sufficient period of HIV-1 suppression with a three-drug antiretroviral regimen, maintenance on fewer drugs may be feasible.

Anti-HIV Agents↗