Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Protease-sparing regimens are sometimes considered the best initial therapy because they can effectively reduce viral load, while allowing the individual to reserve potent protease inhibitor therapy for later treatment. Others contend that the more potent therapy should be used first, to give a patient the best shot at long-term viral suppression. The debate continues with the promotion of efavirenz (Sustiva), a non-nucleoside reverse transcriptase inhibitor (NNRTI), sometimes prescribed as the initial course of therapy. Several reasons are explored for re-evaluating this decision, which is largely based on limited information from one trial with significant results. A table compares efavirenz with Nevirapine and Delavirdine, two other NNRTIs. There are still not enough data to support a recommendation about the use of protease-sparing treatment or the comparative value of the three NNRTIs listed.
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PMID:Strategy update: protease-sparing regimens. 1136 90

Nevirapine (Viramune), a non-nucleoside reverse transcriptase inhibitor, is now approved for use in children. It should be used as part of a three-drug combination for maximum effectiveness and to prevent resistance. In adults Nevirapine is often paired with two nucleoside analogues. Recommended doses for children and possible side effects are presented.
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PMID:Nevirapine in children. 1136

New anti-HIV drugs that are expected to become available in the future are discussed. The potent protease inhibitor amprenavir (Agenerase) is expected to be available in pharmacies by early 1999. Results of a study of treatment-naive, HIV-positive people showed that those taking amprenavir as part of a three-drug combination therapy, with AZT and 3TC, had better viral reduction than those using AZT and 3TC alone. In a French study of the non-nucleoside reverse transcriptase inhibitor Nevirapine, and a similar study of Delavirdine, a majority of participants had HIV RNA levels below the limit of detection. Further comparative studies are needed between Nevirapine, Delavirdine and the more costly, highly publicized competitor, efavirenz. Several studies of regimens that include protease inhibitors compare dosing twice daily to three times a day. A Canadian study describes salvage therapies, for people who have failed previous treatment with protease inhibitors, that can include up to nine drugs. Because there is a shortage in the development of new types of HIV drugs, people are encouraged to carefully consider when to begin treatment and what medical options are available.
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PMID:Antivirals update. 1136 1

None of the studies conducted on people who have reduced the number of antivirals taken in their regimen have shown good results. Research has consistently shown that these people have an increased viral load count when one or more drugs are discontinued. Results from a French study show some promise in switching from a protease inhibitor to a nonnucleoside analogue reverse transcriptase inhibitor (NNRTI) such as Viramune (Nevirapine) or Sustiva (efavirenz). Fifteen out of sixteen participants maintained viral load levels below 200 copies when they changed to an NNRTI regimen. The one person whose viral load increased had taken an NNRTI drug before, although its use was prohibited in eligibility requirements. The strategy may work for people at varying stages of the disease, but larger studies are needed to confirm the results. Also, a fifth protease inhibitor, Amprenavir (Agenerase) has received FDA approval. Trial results are summarized, and side effects and drug interactions with Amprenavir are described.
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PMID:New treatment options. 1136 13

Nevirapine, a nonnucleoside reverse transcriptase inhibitor used as part of combination antiretroviral therapy, can cause mild elevations in transaminase levels. Severe elevations in transaminase levels related to the use of nevirapine developed in 4 patients. Data on these patients were extracted via chart review, and a review of the literature was also completed. Nevirapine-induced hepatitis occurred shortly after drug initiation in patients with and without preexisting liver disease. Significant elevations in liver enzyme levels occurred but resolved promptly in most with discontinuation of the nevirapine. Close monitoring of liver enzyme levels in the early period after starting nevirapine is essential.
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PMID:Nevirapine-induced hepatitis: a case series and review of the literature. 1149 10

Nevirapine (Viramune, Boehringer Ingelheim) is a non-nucleoside reverse transcriptase (RT) inhibitor (NNRTI) effective in the treatment of HIV-1 infected antiretroviral-naive and -experienced patients. Some recent studies have suggested that nevirapine-based regimens may have an efficacy similar to protease inhibitor (PI)-based regimens, at least in naive patients with CD4+ > 200 microl, while it lacks the drawbacks inherent in PI-containing regimens, such as lipodystrophy and metabolic alterations. Switching from a PI-containing regimen to a nevirapine-containing regimen seems to retain the virological response to therapy and it may also limit or reverse the development of some metabolic disorders induced by PIs. Nevirapine is also effective in preventing mother-to-child transmission of HIV-1 disease and in the treatment of HIV-1 infected children. Nevirapine is well-tolerated, rash being the most common severe adverse effect observed. Hepatotoxicity may also appear with nevirapine, mainly in patients with chronic hepatitis C and/or altered liver function tests. This side effect may occasionally be life-threatening but it can be safely managed in most patients.
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PMID:The role of nevirapine in the treatment of HIV-1 disease. 1182 35

Resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs) develops quickly and independently if they are used in combination with NRTIs or protease inhibitors (PIs) as rescue therapy, mainly due to the low genetic barrier of this class of drugs. In this study we examined clinical, therapeutic, and virologic characteristics in 88 patients with mutations conferring resistance to NNRTIs, and in 11 patients 1 year after stopping NNRTI therapy. Between patients administered Nevirapine (NVP) and those taking Efavirenz (EFV), no statistical differences were found in CD4 cell count, HIV viral load, time on NNRTI therapy, or number of PIs administered previously. A slow decline in the detectability of mutations encoding NNRTI resistance was found.
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PMID:Genotype resistance profiles in patients failing an NNRTI-containing regimen, and modifications after stopping NNRTI therapy. 1194 95

Nevirapine (NVP) is a potent non-nucleoside inhibitor of HIV-1 reverse transcriptase. In 1999, the HIVNET 012 trial in Uganda demonstrated that a simple regimen of NVP prophylaxis can dramatically reduce the rate of HIV-1 mother-to-child transmission (MTCT). In the HIVNET 012 regimen, women received a single dose of NVP in labor, and infants received a single dose of NVP within 72 h of birth. The simplicity, efficacy, and low cost of the HIVNET 012 regimen are attractive for prevention of MTCT in resource-poor settings. Plans are underway to implement this regimen in several resource-poor countries. Single mutations in HIV-1 RT can cause high level NVP-resistance and are likely to exist in most HIV-1 infected patients at low levels prior to antiretroviral drug exposure. This favors emergence of NVP-resistant HIV-1 following NVP exposure. NVP-resistant HIV-1 has been shown to emerge in some women and infants following single dose NVP. Emergence of NVP-resistant HIV-1 in this setting is more common among women with high baseline viral loads and low baseline CD4 cell counts. The rate of NVP-resistance in women receiving single dose NVP prophylaxis may also be influenced by HIV-1 subtype. The NVP-resistant HIV-1 typically fades from detection in women and infants over time. We review studies examining the emergence and fading of NVP-resistant HIV-1 in women and infants who received single dose NVP prophylaxis, and discuss the potential clinical relevance of NVP-resistance in this setting.
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PMID:Nevirapine resistance after single dose prophylaxis. 1215 19

HIV-1 protease inhibitors have contributed significantly to the reduction in morbidity and mortality associated with HIV-1 disease. Some of their clinical benefit may be attributed to inhibition of non-viral pathogen proteases and mammalian proteases involved in apoptosis. Our objective was to investigate the effect of HIV-1 protease inhibitors on two different mechanisms of apoptosis in cells not exposed to HIV-1. Modulation of apoptosis induced in U937 or Jurkat cells by CD95 (Fas-ligand) or TNF-alpha was measured using flow cytometry using the 7-AAD and annexin/propidium iodide methods. - HIV-1 protease inhibitors reduced TNF-alpha mediated cell death in a dose-dependent manner, with a maximum inhibition ranging between 38% and 60% observed for 100 microM indinavir. Saquinavir and ritonavir, but not nelfinavir also inhibited TNF-alpha induced cell death. Nevirapine (an HIV-1 reverse transcriptase inhibitor) showed no effect. The TNF-alpha activity was also inhibited by the caspase inhibitors Z-VAD-fmk at concentrations of 10 microM or less, and by DEVD-cmk. In contrast, HIV-1 protease inhibitors did not affect CD95 induced apoptosis in Jurkat cells at any of the concentrations tested. Our findings indicate that HIV-1 protease inhibitors may act on mammalian proteases involved in the regulation of apoptosis; whether this is relevant in the clinical setting remains to be established. Identification of the pathways involved may lead to a better understanding of the clinical impact of this drug class and their role in HAART associated toxicities.
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PMID:Inhibition of TNF-alpha mediated cell death by HIV-1 specific protease inhibitors. 1257 50

Endogenous, nontelomeric reverse transcriptase (RT) is encoded by two classes of repeated elements: retrotransposons and endogenous retroviruses. Expression of RT-coding genes is generally repressed in differentiated nonpathological tissues, yet is active in the mammalian germ line, embryonic tissues and tumor cells. Nevirapine is a non-nucleoside RT inhibitor with a well-characterized inhibitory activity on RT enzymes of retroviral origin. Here, we show that nevirapine is also an effective inhibitor of the endogenous RT in murine and human cell lines. In addition, progenitor and transformed cells undergo a significant reduction in the rate of cell growth upon exposure to nevirapine. This is accompanied by the onset of differentiation, as depicted in F9 and C2C7 progenitor cells cultures in which nevirapine triggers the expression of differentiation-specific markers. Consistent with this, an extensive reprogramming of cell cycle gene expression was depicted in nevirapine-treated F9 cultures. Furthermore, nevirapine exposure rescued the differentiation block present in acute myeloid leukemia (AML) cell lines and primary blasts from two AML patients, as indicated by morphological, functional and immunophenotypic assays. The finding that an RT inhibitor can modulate cell proliferation and differentiation suggests that RT may represent a novel target in the development of therapeutical approaches to neoplasia.
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PMID:Exposure of normal and transformed cells to nevirapine, a reverse transcriptase inhibitor, reduces cell growth and promotes differentiation. 1274 69


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