Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Reverse Transcriptase Inhibitors”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources

Simultaneous determination of the HIV protease inhibitors indinavir, amprenavir, saquinavir, ritonavir, nelfinavir and the non-nucleoside reverse transcriptase inhibitor efavirenz by high-performance liquid chromatography after solid-phase extraction.

As part of an on-going study on the suitability of a formal therapeutic drug monitoring (TDM) of antiviral drugs for improving the management of HIV infection, a high-performance liquid chromatography method has been developed to quantify simultaneously in plasma five HIV protease inhibitors (PIs) (i.e., indinavir, amprenavir, saquinavir, ritonavir, nelfinavir) and the novel non-nucleoside reverse transcriptase inhibitor efavirenz. After viral inactivation by heat (60 degrees C for 60 min), plasma (600 microl), with clozapine added as internal standard, is diluted 1:1 with phosphate buffer, pH 7 and subjected to a solid-phase extraction on a C18 cartridge. Matrix components are eliminated with 2 x 500 microl of a solution of 0.1% H3PO4 neutralised with NaOH to pH 7. PIs and efavirenz are eluted with 3 x 500 microl MeOH. The resulting eluate is evaporated under nitrogen at room temperature and is reconstituted in 100 microl 50% MeOH. A 40-microl volume is subjected to HPLC analysis onto a Nucleosil 100, 5 microm C18 AB column, using a gradient elution of MeCN and phosphate buffer adjusted to pH 5.15 and containing 0.02% sodium heptanesulfonate: 15:85 at 0 min-->30:70 at 2 min-->32:68 at 8 min-->42:58 at 18 min-->46:54 at 34 min, followed by column cleaning with MeCN-buffer, pH 5.15 (90:10), onto which 0.3% AcOH is added. Clozapine, indinavir, amprenavir, saquinavir, ritonavir, efavirenz and nelfinavir are detected by UV at 201 nm at a retention time of 8.2, 13.0, 16.3, 21.5, 26.5, 28.7 and 31.9 min, respectively. The total run time for a single analysis is 47 min, including the washing-out and reequilibration steps. The calibration curves are linear over the range 100-10,000 ng/ml. The absolute recovery of PIs/efavirenz is always higher than 88%. The method is precise with mean inter-day relative standard deviations within 2.5-9.8% and accurate (range of inter-day deviations -4.6 to +4.3%). The in vitro stability of plasma spiked with PIs/efavirenz at 750, 3000 and 9000 ng/ml has been studied at room temperature, -20 degrees C and +60 degrees C. The method has been validated and is currently applied to the monitoring of PIs and efavirenz in HIV patients. This HPLC assay may help clinicians confronted to questionable compliance, side effects or treatment failure in elucidating whether patients are exposed to adequate circulating drug levels. The availability of such an assay represents an essential step in elucidating the utility of a formal TDM for the optimal follow-up of HIV patients.

Alkynes↗

Application of directly coupled LC-NMR-MS to the structural elucidation of metabolites of the HIV-1 reverse-transcriptase inhibitor BW935U83.

The human in vivo metabolism of the HIV-1 reverse transcriptase inhibitor 5-chloro-1-(2',3'-dideoxy-3'-fluoro-erythro-pentofuranosyl)uracil (BW935U83) was studied using 19F NMR spectroscopy, directly coupled LC-NMR and LC-NMR-MS. The number and relative proportions of the drug metabolites were obtained from 19F NMR spectra of whole human urine. The novel use of the continuous-flow 19F detected LC-NMR experiment yielded chromatographic retention times and 19F chemical shifts for the parent drug, the glucuronide conjugate of the parent and an early eluting polar metabolite. The parent drug and its glucuronide conjugate were easily characterised by directly coupled 1H LC-NMR spectroscopy and two-dimensional TOCSY experiments. The identification of the second metabolite was achieved using 19F NMR and directly coupled 1H LC-NMR-MS which furnished the molecular weight, and through the use of MS-MS techniques, information on the fragment ions. This species was identified as 3-fluoro-ribolactone.

Anti-HIV Agents↗

Column selection and method development for the determination of the enantiomeric purity of investigational non-nucleoside reverse transcriptase inhibitors.

DPC 961 and DPC 083 are investigational non-nucleoside reversed transcriptase inhibitors (NNRTI) being evaluated for the treatment of HIV infections (Corbett et al., Antimicrob Agents Chemother 1999;43:2893-2897). Both compounds are chiral and are synthesized as single enantiomers by an asymmetric synthetic pathway (Magnus et al., Tetrahedron Lett 2000;41:3015-3019). A chiral method was developed to control the enantiomeric purity of the drug substance and to monitor for any chiral inversion in the drug substance and in the tablet formulation during stability studies. Three columns were evaluated: Chiralpak AD, Chirobiotic V, and Whelk-O. All three columns have broad applicability and can resolve enantiomers of compounds of very diverse molecular structure and polarity. The three columns were evaluated with various mobile phase compositions for their ability to resolve the racemic mixtures of DPC 083, DPC 961, and their respective enantiomers and for their selectivity toward the synthetic impurities of the two drug substances. Nonaqueous mobile phases were selected because the two drugs are poorly water soluble. The separation between the unwanted enantiomer of DPC 083 and DPC 961, which is a major impurity of DPC 083, in particular, was closely monitored. The final method was fully validated and is used for the routine testing of the drug substance and tablets.

Anti-HIV Agents↗

A rapid bioassay for the determination of non-nucleoside HIV-1 reverse transcriptase inhibitor plasma levels.

A rapid method for measuring pyridinone HIV-1 reverse transcriptase inhibitor plasma levels was necessary for identifying potential clinical candidates and for choosing a clinical formulation. Due to its sensitivity to the pyridinones, ability to tolerate extraneous material, and its capability for rapid, high through-put screening, the HIV-1 RT assay was developed into a bioassay for determining plasma levels of the pyridinones in Rhesus monkey plasma. With this assay, dose proportionality of L-697, 639 was established. Formulation studies using L-697, 639 indicated that the plasma levels achieved in Rhesus monkeys with the clinical formulation (peak levels = 3.9 microM at 30 min) fall between the levels achieved with polyethylene glycol 300 and hydroxypropyl methyl cellulose formulations (peak levels = 8.9 microM and 0.4 microM respectively, at 60 min). Two other pyridinones, L-696, 229 and L-697, 661, administered as the clinical formulation, had peak plasma levels of 1.6 microM (30 min) and 0.3 microM (60 min), respectively. In Rhesus monkeys, the bioavailabilities of these compounds (administered as the clinical formulation) ranged from 11 to 24% and their half-life values ranged from 24 to 120 min. The results of oral studies in Rhesus monkeys with these compounds were very similar to initial results of studies in humans.

Administration, Oral↗

Pharmacokinetics of single oral doses of apricitabine, a novel deoxycytidine analogue reverse transcriptase inhibitor, in healthy volunteers.

BACKGROUND: Apricitabine is a novel deoxycytidine analogue reverse transcriptase inhibitor that is undergoing clinical development for the treatment of HIV-1 infection. This study was performed to investigate the pharmacokinetics of single oral doses of apricitabine in healthy volunteers. METHODS: A total of 26 healthy volunteers (14 males, 12 females) took part in this study. Participants received single oral doses of apricitabine 400 mg, 800 mg and 1600 mg in ascending order at intervals of at least 1 week. Concentrations of apricitabine in plasma and urine were monitored over 24 hours after dosing. RESULTS: Apricitabine was rapidly absorbed after oral administration, with peak plasma concentrations (Cmax) being attained approximately 1.5-2 hours after dosing. Plasma concentrations declined in a log-linear manner over at least 12 hours, with an elimination half-life of approximately 3 hours. The majority of the dose (65-80%) was excreted in the urine as unchanged drug within 24 hours. The pharmacokinetics of apricitabine were largely linear with respect to dose. In the overall study population, the area under the concentration-time curve (AUC) decreased by 4% with a dose of 800 mg and by 14% with the 1600 mg dose compared with the value predicted from the 400 mg dose. In females, however, there was a slightly greater departure from linearity: AUC decreased by 8% with a dose of 800 mg, and by 21% with a dose of 1600 mg. When pharmacokinetic parameters were normalised for bodyweight, there were no significant differences between values in males and females. There was no evidence of enantiomeric interconversion of apricitabine. All doses of apricitabine were well tolerated. CONCLUSION: Apricitabine is rapidly absorbed and shows predictable pharmacokinetics after oral administration. Clearance is predominantly by renal excretion of the unchanged drug, which suggests a low potential for interactions with drugs that are subject to hepatic metabolism.

Administration, Oral↗

Emerging reverse transcriptase inhibitors for the treatment of HIV infection in adults.

A combination of three or more antiretroviral drugs, commonly called 'highly active antiretroviral therapy' (HAART), has become the standard-of-care treatment for HIV-infected patients in the developed world. There are now 21 licensed anti-HIV drugs to choose from when starting a HAART regimen. The currently approved antiretroviral drugs fall into four categories: nucleoside/nucleotide reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, protease inhibitors and fusion inhibitors. Novel compounds currently in preclinical or clinical development are either focusing on new viral proteins or the same specific viral elements targeted by the available drugs. When developing new anti-HIV drugs of an already existing class, focus should be held on maximising potency, minimising toxicity, diminishing the risk for resistance development and producing effective drugs for patients who already have resistance to currently available drugs. In addition, pill burden should be ideally reduced to once-daily dosing, thereby enhancing a patient's adherence and reducing treatment costs. The present review focuses on emerging drugs to inhibit the reverse transcriptase of HIV.

Adult↗

Triple nucleoside reverse transcriptase inhibitor therapy in children.

Much of the success attributed to HIV therapy in the last few years has resulted from improved ways of using existing drugs in combination therapy regimens. The availability of new, more potent drugs such as protease inhibitors and more accurate viral load tests to aid decisions to start or change treatment has also contributed to the success. Published recommendations for pediatric HIV therapy, generated by a panel of experts and specialists, are readily available and regularly updated. Preferred regimens of 'potent' therapy (referred to as highly active antiretroviral therapy, or HAART) currently consist of two nucleoside reverse transcriptase inhibitors (NRTIs) combined with either a non-nucleoside reverse transcriptase inhibitor (NNRTI) or a protease inhibitor. More intense four-drug regimens using an NNRTI or a second protease inhibitor as a fourth drug are being evaluated. Problems with HAART include: unpalatable drug formulations and adverse effects, coupled with lack of data on the pharmacokinetics, efficacy, and safety of various drug combinations. Adherence is a major factor influencing the efficacy and outcome of antiretroviral therapy. Many children cannot adhere to complex multidrug regimens, which cause virologic failure, despite excellent CD4+ cell count responses. This means a rapid progression through the limited number of treatment regimens available. Simpler regimens such as those containing three NRTIs have been proposed as a method of treatment that will allow suppression of the virus, yet circumvent many of the problems previously mentioned. An additional benefit would be the preservation of antiretroviral drugs from other classes for future treatment options if required. The major advantages of triple NRTI regimens are the simplicity of the regimen, good tolerability, few drug-drug interactions, and infrequent adverse effects coupled with a low pill burden. However, abacavir hypersensitivity remains a major problem. Up to 3% of patients may develop an early idiosyncratic hypersensitivity reaction - fever, malaise, and mucositis with or without rash, which can progress to more advanced stages of shock and death. A major concern is the apparently inferior virologic control of triple NRTI therapy as demonstrated in the AIDS Clinical Trials Group A5095 study with zidovudine/lamivudine/abacavir (Trizivir) combination in adults. Such a combination should only be considered in special situations. Examples cited include informed patient choice based on anticipated poor adherence on other treatment regimens, or if concomitant drugs such as tuberculosis medication are prescribed. The low pill burden of triple NRTI regimens (especially if combined in a single pill such as Trizivir), offers hope that regimen simplification may still be possible in the future.

Antiretroviral Therapy, Highly Active↗

The clinical relevance of non-nucleoside reverse transcriptase inhibitor hypersusceptibility: a prospective cohort analysis.

OBJECTIVE: To evaluate the clinical significance of hypersusceptibility to non-nucleoside reverse transcriptase inhibitors (NNRTI). DESIGN: Analysis of a prospective clinical trial cohort. PATIENTS: NNRTI-naive patients failing a stable antiretroviral regimen. MEASUREMENTS: HIV phenotype, HIV RNA, and CD4 cell counts were prospectively collected after patients changed to a new regimen. Hypersusceptibility to NNRTI was defined as a fold-change (FC) in IC50 (inhibitory concentration of 50%) of < 0.4. RESULTS: The 177 patients had a mean HIV RNA of 4.1 log10 copies/ml, CD4 cell count of 322 x 10(6) cells/l and 41 months of prior antiretroviral treatment. Hypersusceptibility to one or more NNRTI was present in 29%. Both longer duration and reduced susceptibility to nucleoside reverse transcriptase inhibitors were associated with efavirenz hypersusceptibility (P < 0.05). NNRTI-containing regimens were initiated in 106 patients at baseline. The mean change in log HIV RNA after 6 months was greater for patients with hypersusceptibility (-1.2 log10 copies/ml; n = 21) than in patients without (-0.8 log10 copies/ml; n = 77) (P = 0.016). Differences persisted to month 12 (P = 0.023). Multiple linear regression models confirmed that hypersusceptibility to NNRTI was a significant independent predictor of the magnitude of early (months 1-4) HIV RNA reduction, after accounting for the baseline HIV RNA and the number of drugs to which the patient's virus was susceptible (P < 0.02). CD4 cell increases (months 4-10) were 28- 60 x 10(6) cells/l greater in patients with hypersusceptible virus (P < or = 0.1). CONCLUSION: NNRTI hypersusceptibility occurred in more than 20% of nucleoside-experienced patients and was associated with greater reduction of HIV RNA and increase in CD4 cells.

Adult↗

[Development of new reverse transcriptase inhibitors].

Highly active anti-retroviral therapy(HAART) using two or more reverse transcriptase inhibitors(RTIs) and protease inhibitors, has dramatically improves the quality of life and survival of patients infected with human immunodeficiency virus(HIV). RTIs are categorized by their mechanism of action, into two groups, nucleoside(N) and non-nucleoside(NN) RTIs. However, resistant HIV variants against NRTIs and/or NNRTIs including multi-drug resistant, emerge after the prolonged therapy. To suppress the replication of such resistant variants, numerous anti-HIV drugs have been developed. In this review, the mechanisms of action and characters of the major drugs in clinical or under preclinical are described.

Anti-HIV Agents↗

In vitro suppression of the lipogenic pathway by the nonnucleoside reverse transcriptase inhibitor efavirenz in 3T3 and human preadipocytes or adipocytes.

A serious metabolic syndrome combining insulin-resistance, dyslipidemia, central adiposity, and peripheral lipoatrophy has arisen in HIV-infected patients receiving highly active antiretroviral therapy. The aim of this work was to examine the effects of the nonnucleoside reverse transcriptase inhibitor (NNRTI) efavirenz on adipocyte differentiation and metabolism. When induced to differentiate in the presence of efavirenz (5-50 microm), 3T3-F442A preadipocytes failed to accumulate cytoplasmic triacylglycerol droplets. This phenomenon was rapidly reversible and was also readily detectable in the 3T3-L1 preadipose cell line and in primary cultures of human preadipocytes. When applied to mature 3T3-F442A adipocytes, efavirenz induced a delayed and moderate reduction in cell triglyceride content. Measurement of [(3)H]deoxyglucose uptake, basal and agonist-stimulated lipolysis, and cell viability indicated that these pathways are not involved in efavirenz effects on triacylglycerol accumulation. By contrast, we found that the NNRTI induced a dramatic dose- and time-dependent decrease in gene and protein expression of the lipogenic transcription factor sterol regulatory element-binding protein-1c (SREBP-1c). Adipose conversion was only altered at the highest efavirenz concentrations, as suggested by the mild reduction in peroxisome proliferator-activated receptor-gamma and CCAAT/enhancer-binding protein-alpha. CCAAT/enhancer-binding protein-beta remained unchanged. The inhibition of SREBP-1c expression was accompanied by a sharp reduction in the expression of SREBP-1c target genes and in the adipocyte lipogenic activity in efavirenz-treated cells. Finally, the inhibitory effect of efavirenz on cell triglyceride accumulation was prevented by directly providing free fatty acids to the cells and was reversed by overexpression of a dominant positive form of SREBP-1c, reinforcing the implication of this transcription factor in the antilipogenic effect of the drug. When considered together, these results demonstrate for the first time that the NNRTI efavirenz induces a strong inhibition of the SREBP-1c-dependent lipogenic pathway that might contribute to adipose tissue atrophy.

3T3 Cells↗

The nonnucleoside reverse transcriptase inhibitors efavirenz and nevirapine in the treatment of HIV.

Clinical trial data and real-world experience have shown the nonnucleoside reverse transcriptase inhibitors (NNRTIs) to be an important class of agents for the treatment of HIV. Given their long plasma half-lives, in vitro and in vivo potency against HIV, low pill burdens, and ability to be safely combined with other commonly used medications, the NNRTIs nevirapine and efavirenz are widely used in combination antiretroviral therapies. Observational, retrospective cohort studies among antiretroviral treatment (ART)-naive patients have suggested that efavirenz may be superior to nevirapine in terms of efficacy. Recently, data from the 2NN study, a large, multicenter, multinational, prospective, randomized, head-to-head trial comparing efavirenz and nevirapine, have been reported. The results from this study indicate that ART-naive patients achieved good antiviral response after 48 weeks of treatment with nucleoside reverse transcriptase inhibitors (NRTIs) combined with either efavirenz or nevirapine (viral load >50 copies/mL: efavirenz, 70%; nevirapine bid, 65.4%; nevirapine qd, 70%). Even though central nervous system disturbances occurred more frequently among efavirenz-treated patients and nonclinically significant transaminitis occurred more frequently among nevirapine-treated patients, these adverse events were not statistically significant or mutually exclusive. Given the results of the 2NN study, the selection of one agent or the other for use in clinical practice will depend more upon patient-specific factors than expected differences in antiviral responses.

Alkynes↗

In vitro selection of mutations in human immunodeficiency virus type 1 reverse transcriptase that confer resistance to capravirine, a novel nonnucleoside reverse transcriptase inhibitor.

Capravirine (CPV; formerly AG1549 and S-1153) is a novel, nonnucleoside reverse transcriptase inhibitor (NNRTI) of human immunodeficiency virus type 1 (HIV-1) that has demonstrated potent in vitro antiviral activity against several HIV-1 laboratory strains and clinical isolates with EC50 values ranging from 0.7 to 10.3 nM. In this study, we evaluated the resistance and cross-resistance profiles of CPV through selection of resistant HIV-1 variants from in vitro serial passage of HIV-1 NL4-3 and HIV-1 IIIB and by performing susceptibility assays on HIV-1 variants constructed to contain CPV-specific amino acid substitutions in reverse transcriptase (RT). Results demonstrate that HIV-1 variants selected at increasing CPV concentrations contained multiple substitutions in diverse patterns including L100I, Y181C, G190E and/or L234I in various combinations with K101R/E, K103T, V106A/I, V108I, E138K, T139K, A158T, V179D/I/G, Y188D, V189I, G190A, F227C, W229R, L234F, M230I/L and P236H/T. Interestingly, HIV-1 variants constructed to contain the T215Y zidovudine (AZT)-resistance associated substitution with CPV-resistance associated substitutions V106A, Y181C, F227C, F227L, L234I or V106A/F227L demonstrated 2.4-5.4-fold increased susceptibility to CPV. Results also demonstrate that the CPV-resistance associated substitutions Y181C, F227C, F227L and L234I reverse the phenotypic resistance to AZT conferred by the T215Y substitution.

Anti-HIV Agents↗

Knocking out human immunodeficiency virus through non-nucleoside reverse transcriptase inhibitors used as single agents or in combinations: a paradigm for the cure of AIDS?

A large variety of compounds have been reported to inhibit the replication of human immunodeficiency virus (HIV). The compounds that have been most intensively pursued for the treatment of HIV infection belong to three classes: nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs). Within each of these classes, a number of compounds have been identified that inhibit HIV replication at nanomolar concentrations which are 10(4)- to 10(5)-fold lower than the cytotoxic concentrations. Yet, the potential usefulness of these compounds seems to be compromised by the rapid emergence of virus drug resistance. Here, we describe a strategy that, at least in cell culture, prevents the development of resistance. This strategy is based on the use, from the beginning, of sufficiently high drug concentrations. When added at such concentrations, that for some of the NNRTIs did not have to be higher than 10-100 times their 50% effective concentration (EC50), these compounds completely suppressed ("knocked out") HIV-1 replication in cell culture, and thus prevented drug-resistant virus strains from emerging. This "knock out" effect could be achieved for longer times and at lower drug concentrations when the compounds were combined (i.e. NNRTIs with one another or with NRTIs) than when used individually. Thus, when used at the appropriate doses, as such or in combination, NNRTIs proved able to completely clear ("cure") HIV-1-infected cell cultures from the virus.

Drug Combinations↗

Targeting delavirdine/atevirdine resistant HIV-1: identification of (alkylamino)piperidine-containing bis(heteroaryl)piperazines as broad spectrum HIV-1 reverse transcriptase inhibitors.

A novel class of bis(heteroaryl)piperazine (BHAP) analogs which possesses the ability to inhibit NNRTI (non-nucleoside reverse transcriptase inhibitor) resistant recombinant HIV-1 reverse transcriptase (RT) and NNRTI resistant variants of HIV-1 has been identified via targeted screening. Further investigation of the structure-activity relationships of close congeners of these novel (alkylamino)piperidine BHAPs (AAP-BHAPs) led to the synthesis of several compounds possessing the desired phenotype (e.g., activity against recombinant RTs carrying the Y181C and P236L substitutions). Further structural modifications were required to inhibit metabolism and modulate solubility in order to obtain compounds with the desired biological profile as well as appropriate pharmaceutical properties. The AAP-BHAPs with the most suitable characteristics were compounds 7, 15, and 36.

Animals↗

Phenotypic hypersusceptibility to non-nucleoside reverse transcriptase inhibitors in treatment-experienced HIV-infected patients: impact on virological response to efavirenz-based therapy.

BACKGROUND: Enhanced susceptibility to non-nucleoside reverse transcriptase inhibitors (NNRTI) was recently described in association with increased resistance to nucleoside analogs (nucleoside reverse transcriptase inhibitors; NRTI). OBJECTIVES: To determine the prevalence of NNRTI hypersusceptibility, the genotypic correlates, and its impact on virologic response to efavirenz-based salvage therapy. METHODS: Genotype and phenotype testing was performed retrospectively on baseline isolates from 30 patients who received salvage therapy containing efavirenz. NNRTI hypersusceptibility was defined as a 50% inhibitory concentration (IC(50)) of < 0.5 that of the wild-type control. RESULTS: Eight isolates had major NNRTI mutations. Among the 22 isolates with no major NNRTI mutations, 11 (50%) were hypersusceptible to efavirenz, 10 (45%) to delavirdine, and eight (36%) to nevirapine. Among eight isolates with NNRTI mutations, NNRTI resistance was present, but at lower than expected levels. The number of NRTI mutations was correlated inversely with the fold decrease in susceptibility to efavirenz (Spearman's rho, -0.57; P = 0.005), delavirdine (rho, -0.43; P = 0.04), and nevirapine (rho, -0.69; P < 0.001). Excluding subjects with NNRTI mutations, subjects with efavirenz hypersusceptibility at baseline had significantly better virologic suppression over 24 weeks than those without efavirenz hypersusceptibility (P < 0.001). CONCLUSION: NNRTI hypersusceptibility is common in heavily treated but NNRTI naive patients and is related directly to NRTI resistance mutations. Among patients receiving efavirenz-containing regimens, NNRTI hypersusceptibility was associated with an improved virologic outcome after 24 weeks of therapy. A reversal of phenotypic resistance was seen in patients with NNRTI mutations in the presence of multiple NRTI mutations, but no obvious virologic benefit of this phenomenon was seen in this study.

Alkynes↗

Synthesis and biological evaluations of sulfanyltriazoles as novel HIV-1 non-nucleoside reverse transcriptase inhibitors.

A novel sulfanyltriazole was discovered as an HIV-1 non-nucleoside reverse transcriptase inhibitor via HTS using a cell-based assay. Chemical modifications and molecular modeling studies were carried out to establish its SAR and understand its interactions with the enzyme. These modifications led to the identification of sulfanyltriazoles with low nanomolar potency for inhibiting HIV-1 replication and promising activities against selected NNRTI resistant mutants. These novel and potent sulfanyltriazoles could serve as advanced leads for further optimization.

Anti-HIV Agents↗

Susceptibility of human T cell leukemia virus type 1 to reverse-transcriptase inhibitors: evidence for resistance to lamivudine.

Nucleoside reverse-transcriptase (RT) inhibitors (NRTIs), including lamivudine (3TC) and zidovudine (Zdv), are being evaluated for the treatment of human T cell lymphotropic virus type 1 (HTLV-1)-associated disease. However, information on the susceptibility of HTLV-1 to these drugs is limited. The activity of 5 NRTIs on HTLV-1 RT was evaluated. IC(50) values for Zdv, zalcitabine (ddC), didanosine (ddI), 3TC, and stavudine (d4T) were determined, using an enzymatic assay, for 5 HTLV-1 isolates and for reference wild-type and NRTI-resistant human immunodeficiency virus type 1 (HIV-1). Both HTLV-1 and wild-type HIV-1 were equally susceptible to Zdv, ddC, ddI, and d4T. In contrast, high-level resistance to 3TC was found in all HTLV-1 isolates. The findings support the clinical use of Zdv, ddC, ddI, and d4T but not of 3TC for the antiretroviral treatment of HTLV-1-associated disease.

Amino Acid Sequence↗

Synthesis of certain heterodimers expected as HIV-1 reverse transcriptase inhibitors.

Expected for the ability to inhibit HIV replication, we report the synthesis of two heterodimers of the general formula: [2NRTI]-C5-GLY-SUCCINYL-Npiperazinyl-[NNRTI] (18, 19) containing both a Nucleoside Reverse Transcriptase Inhibitor (10, 11) and a Non-Nucleoside Reverse Transcriptase Inhibitor (8) [Trovirdine Analogue belonging of the phenethyl thiazolyl thiourea class] connected through the "succinyl-glycine" spontaneously cleavable linker.

Dimerization↗