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At least 685 records · Page 38Linked to original sources
PubMed2006

Efficacy and safety of an anti-retroviral combination regimen including either efavirenz or lopinavir-ritonavir with a backbone of two nucleoside reverse transcriptase inhibitors.

The efficacy and safety of a combination regimen including either efavirenz or lopinavir-ritonavir was examined in a cohort of 65 patients positive for human immunodeficiency virus-1 (HIV-1). Both the efavirenz (n = 33, 18 anti-retroviral naive) and lopinavir-ritonavir (n = 32, 15 naive) regimens achieved significant changes from baseline CD4 cell counts and HIV RNA levels after 108 weeks (p < 0.01). Despite diminished immunological and virological parameters at study entry, the lopinavir-ritonavir group showed greater virological effects than the efavirenz group after 108 weeks (median change 3.3 log(10), interquartile range (IQR) 2.2-3.8 log(10) vs. 2.4 log(10), IQR 0.9-3.3 log(10), respectively, p 0.004). Use of lopinavir-ritonavir, in contrast to use of efavirenz, was associated with significant hypertriglyceridaemia.

Adult↗
PubMed2002

In search of high stereocontrol for the construction of cis-disubstituted cyclopropane compounds. Total synthesis of a cyclopropane-configured urea-PETT analogue that is a HIV-1 reverse transcriptase inhibitor.

[reaction: see text] A new azetidine-ligated dirhodium(II) catalyst that possesses a l-menthyl ester attachment provides significant diastereocontrol and high enantiocontrol for the formation of cis-cyclopropane products from reactions of substituted styrenes with diazo esters.

Cyclopropanes↗
PubMed2002

Potent inhibition of human immunodeficiency virus type 1 replication by template analog reverse transcriptase inhibitors derived by SELEX (systematic evolution of ligands by exponential enrichment).

RNA aptamers derived by SELEX (systematic evolution of ligands by exponential enrichment) and specific for human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) bind at the template-primer cleft with high affinity and inhibit its activity. In order to determine the potential of such template analog RT inhibitors (TRTIs) to inhibit HIV-1 replication, 10 aptamers were expressed with flanking, self-cleaving ribozymes to generate aptamer RNA transcripts with minimal flanking sequences. From these, six aptamers (70.8,13, 70.15, 80.55,65, 70.28, 70.28t34, and 1.1) were selected based on binding constants (K(d)) and the degree of inhibition of RT in vitro (50% inhibitory concentration [IC(50)]). These six aptamers were each stably expressed in 293T cells followed by transfection of a molecular clone of HIV(R3B). Analysis of the virion particles revealed that the aptamers were encapsidated into the virions released and that the packaging of the viral genomic RNA or the cognate primer, tRNA(Lys)(3), was apparently unaffected. Infectivity of virions produced from 293T cell lines expressing the aptamers, as measured by infecting LuSIV reporter cells, was reduced by 90 to 99.5% compared to virions released from cells not expressing any aptamers. PCR analysis of newly made viral DNA upon infection with virions containing any of the three aptamers with the strongest binding affinities (70.8,13, 70.15, and 80.55,65) showed that all three were able to form the minus-strand strong-stop DNA. However, virions with the aptamers 70.8 and 70.15 were defective for first-strand transfer, suggesting an early block in viral reverse transcription. Jurkat T cells expressing each of the three aptamers, when infected with HIV(R3B), completely blocked the spread of HIV in culture. We found that the replication of nucleoside analog RT inhibitor-, nonnucleoside analog RT inhibitor-, and protease inhibitor-resistant viruses was strongly suppressed by the three aptamers. In addition, some of the HIV subtypes were severely inhibited (subtypes A, B, D, E, and F), while others were either moderately inhibited (subtypes C and O) or were naturally resistant to inhibition (chimeric A/D subtype). As virion-encapsidated TRTIs can predispose virions for inhibition immediately upon entry, they should prove to be efficacious agents in gene therapy approaches for AIDS.

Anti-HIV Agents↗
PubMed1994

Characterization of the anti-HIV-1 activity of 3,4-dihydro-2-alkoxy-6-benzyl-4-oxopyrimidines (DABOs), new non-nucleoside reverse transcriptase inhibitors.

Novel 3,4-dihydro-6-benzyl-4-oxopyrimidines (DABOs), variously substituted at both the C-2 and C-5 positions of the pyrimidine ring, proved to be specific inhibitors of the human immunodeficiency virus type 1 (HIV-1) in vitro. Some compounds showed potency at micromolar doses, no cytotoxicity at the maximum testable doses and selectivity indexes comparable to that of 2'-3'-dideoxyinosine (ddI). Mode of action studies suggested that DABOs interfered with a step of the virus multiplication cycle following adsorption and preceding integration. Enzyme assays indicated that DABOs targeted HIV-1 reverse transcriptase: they inhibited the RNA-dependent DNA polymerase activity in a template-dependent manner and, to a lesser extent, the DNA-dependent DNA polymerase activity. No inhibition of the RNase-H associated activity was observed. When DABOs were assayed in combination with 3'-azido-3'-dideoxythymidine (AZT) or ddI against HIV-1 in cell cultures, a slightly synergistic inhibitory effect was observed. The combination of DABO 546 and AZTTP in enzyme assays showed that the two compounds were kinetically mutually exclusive.

Antiviral Agents↗
PubMed2004

Mutations linked to drug resistance, human immunodeficiency virus type 1 biologic phenotype and their association with disease progression in children receiving nucleoside reverse transcriptase inhibitors.

BACKGROUND: Few data are available concerning the impact of antiretroviral resistance in response to antiviral therapy in children. We evaluated the development of antiretroviral genotypic resistance and clinical outcome in a subgroup of children involved in a prospective antiretroviral therapy trial (Pediatric AIDS Clinical Trials Group Protocol 152). DESIGN: We studied 26 matched case/control pairs. A case was defined as having clinical disease progression during the study period; controls did not have disease progression. Cases and controls were matched by age and CD4+ cell count at baseline. Matched pairs received treatment with zidovudine (9 pairs), didanosine (12 pairs) or combined therapy (5 pairs). Multiple codons of the reverse transcriptase coding region (41, 67, 70, 74, 151, 184, 210, 215 and 219) were analyzed. Patients were evaluated for CD4+ cell count, HIV-1 viral load and HIV-1 biologic phenotype at baseline and clinical endpoint. RESULTS: The presence of mutations associated with resistance after nucleoside antiretroviral therapy (P = 0.039) and syncytium-inducing phenotype (P = 0.031), were significantly associated with increased risk of clinical disease progression. The mean difference in HIV-1 RNA levels between cases and their matched controls after nucleoside antiretroviral therapy was 0.77 log10 copies/ml higher for cases (P = 0.003). The median difference between cases and controls for CD4+ cell count after nucleoside antiretroviral therapy was 349 cells/mm3 lower for cases (P < 0.001). CONCLUSIONS: In this small prospective study of HIV-infected children, mutations in the reverse transcriptase coding region, syncytium-inducing viral phenotype, higher HIV-1 RNA load and lower CD4+ cell count were significantly correlated with increased risk of HIV clinical disease progression.

CD4 Lymphocyte Count↗
PubMed2002

Determination of efavirenz, a selective non-nucleoside reverse transcriptase inhibitor, in human plasma using HPLC with post-column photochemical derivatization and fluorescence detection.

Methods for the quantitative determination of efavirenz in human plasma and the qualitative assessment of the stereochemical integrity of efavirenz in post-dose human plasma samples are described. After the addition of an internal standard, plasma samples were extracted with hexane-methylene chloride (65/35, v/v%). The extracts were evaporated to dryness and reconstituted in mobile phase. Upon exposure to UV light, the analyte was found to form fluorescent products; the major fluorescent product was isolated and identified as a substituted quinoline. Thus, the plasma extracts were analyzed via HPLC with post-column photochemical derivatization and fluorescence detection. Reverse phase chromatography was used for the quantitative assay, whereas chromatography with a column containing a chiral stationary phase (dinitrobenzoyl leucine) was used for the stereochemical assessment. The quantitative assay has been validated in the concentration range of 50-1000 ng/ml using 0.5 ml samples. Analyte recovery was better than 89% at all points on the standard curve. Intra-day precision was better than 5% C.V., while accuracy was between 95 and 104% of nominal over the range of the assay. The selective detection method reduces the likelihood of interference by co-administered medications or endogenous species. The stereochemical configuration of efavirenz was confirmed to remain intact in post-dose human plasma samples. The quantitative method has been successfully utilized to support a study in which a possible drug interaction between co-administered HIV protease inhibitors and efavirenz was evaluated.

Alkynes↗
PubMed1999

Antiviral activity of the human immunodeficiency virus type 1-specific nonnucleoside reverse transcriptase inhibitor HBY 097 alone and in combination with zidovudine in a phase II study. HBY 097/2001 Study Group.

The safety and antiviral activity of the second-generation nonnucleoside inhibitor HBY 097 was investigated in asymptomatic or mildly symptomatic human immunodeficiency virus (HIV)-1-infected patients in a randomized, double-blinded, dose-escalation study. Mean maximum virus load decreases ranged from -1.31 log10 copies/mL of plasma at week 1 in the group receiving HBY 097 monotherapy (250 mg three times daily) to -2.19 log10 copies/mL at week 4 in the group receiving zidovudine plus HBY 097 (750 mg three times daily). After 12 weeks, these patients had viral RNA copy numbers 1.05 log10 below baseline. Genotypic analysis of resistance development revealed reverse transcriptase K103N variants in most patients, which was associated with less durable efficacy of HBY 097 treatment. Fewer patients receiving combination therapy with high-dose HBY 097 developed the K103N variant (P<.01). HBY 097 caused pronounced acute suppression of HIV-1 replication both in combination with zidovudine and alone. Therefore, sustained antiviral activity can be expected from multiple combination therapy regimens including a quinoxaline derivative.

Adult↗
PubMed2005

Improving the antiviral efficacy and selectivity of HIV-1 reverse transcriptase inhibitor TSAO-T by the introduction of functional groups at the N-3 position.

Novel derivatives of the anti-HIV-1 agent, TSAO-T, bearing at the N-3 position a variety of polar, lipophilic, or aromatic groups linked to that position through flexible polymethylene linkers of different length, were prepared and evaluated for their anti-HIV activity. Several compounds (within the series of polar bearing groups) exhibited a 2-6-fold improved antiviral potency with regard to the lead compound, TSAO-T. Moreover, some of the most active N-3 TSAO derivatives retain antiviral activity against the TSAO-T-resistant HIV-1 strain (Glu138 --> Lys). Interestingly, the N-methylcarboxamide derivative 17 was 5- to 6-fold more active (IC50: 0.56 microM) against recombinant HIV-1 reverse transcriptase than the lead compound, thus becoming the most active TSAO derivative synthesized so far. On the other hand, the N-3 methylcarboxamide TSAO derivative 12 turned out to have the highest selectivity index yet reported for this class of compounds (around > or =12 000).

Anti-HIV Agents↗
PubMed2001

4,1-Benzoxazepinone analogues of efavirenz (Sustiva) as HIV-1 reverse transcriptase inhibitors.

A series of 4,1-benzoxazepinone analogues of efavirenz (Sustiva) as potent NNRTIs has been discovered. The cis-3-alkylbenzoxazepinones are more potent then the trans isomers and can be synthesized preferentially by a novel stereoselective cyclization. The best compounds are potent orally bioavailable inhibitors of both wild-type HIV-1 and its clinically relevant K103N mutant virus, but are highly protein-bound in human plasma.

Alkynes↗
PubMed2006

A novel potent non-nucleoside reverse transcriptase inhibitor acylthiocarbamate derivative with extensive intramolecular pi-pi interactions.

In the crystal structure of the novel acylthiocarbamate derivative O-[2-(1,3-dioxo-2,3-dihydro-1H-isoindol-2-yl)ethyl] N-(4-methylphenyl)-N-(3-nitrobenzoyl)thiocarbamate, C25H19N3O6S, intra- and intermolecular pi-pi interactions occur between the phthalimide and N-benzoyl moieties. The partial atomic charges, calculated by ab initio methods, are consistent with the observed structure.

Crystallography, X-Ray↗
PubMedDate not supplied

An efficient, scalable synthesis of the HIV reverse transcriptase inhibitor Ziagen (1592U89).

Ziagen, (1S,cis)-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]- 2-cyclopentene-1-methanol, was synthesized from (1S,4R)-azabicyclo[2.2.1]hept-5-en-3-one by efficient processes which bypass problematic steps in earlier routes. 2-Amino-4,6-dichloro-5-formamidopyrimidine is a key intermediate which makes possible an efficient construction of the purine from a chiral cyclopentenyl precursor.

Anti-HIV Agents↗
PubMed2001

Mechanisms of HIV-1 nucleoside reverse transcriptase inhibitor resistance: is it all figured out?

The mechanistic basis for some examples of HIV-1 NRTI-resistance can be examined using altered incorporation of nucleoside analogs and surveying what is known about the more recently described mechanisms of chain-terminator removal. The complexity of these resistance mechanisms and the interplay with other factors that contribute to NRT1 resistance are only just beginning to be appreciated.

Adenine↗