Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ribavirin used in therapies against hepatitis C virus (HCV) is potentially efficient against other viruses but presents a high cytotoxicity. Several ribavirin triphosphate analogs modified on the ribose moiety were synthesized and tested in vitro on the RNA polymerases of HCV, phage T7, and HIV-1 reverse transcriptase. Modified nucleotides with 2'-deoxy, 3'-deoxy, 2',3'-dideoxy, 2',3'-dideoxy-2',3'-dehydro, and 2',3'-epoxy-ribose inhibited the HCV enzyme but not the other two polymerases. They were also analyzed as substrates for nucleoside diphosphate (NDP) kinase, the enzyme responsible for the last step of the cellular activation of antiviral nucleoside analogs. An X-ray structure of NDP kinase complexed with ribavirin triphosphate was determined. It demonstrates that the analog binds as a normal substrate despite the modified base and confirms the crucial role of the 3'-hydroxyl group in the phosphorylation reaction. The 3'-hydroxyl is required for inhibition of the initiation step of RNA synthesis by HCV polymerase, and both sugar hydroxyls must be present to inhibit elongation. The 2'deoxyribavirin is the only derivative efficient in vitro against HCV polymerase and properly activated by NDP kinase.
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PMID:Structural analysis of the activation of ribavirin analogs by NDP kinase: comparison with other ribavirin targets. 1260 60

Pancreatitis and lactic acidosis are severe and life-threatening adverse events associated with nucleoside analogue antiretroviral therapy used to treat HIV infection. The drug from this class most commonly associated with these adverse events is stavudine, although zidovudine and didanosine have also been implicated. Ribavirin is a nucleoside analogue used in combination with interferon alfa to treat hepatitis C. Because of similar mechanisms of action, the combination of these 2 drugs could potentially increase such toxicity. A case of fatal lactic acidosis and pancreatitis is described in an HIV-infected patient coinfected wtih hepatitis C on a didanosine-containing antiretroviral regimen after treatment of hepatitis C was initiated with ribavirin and pegylated interferon alfa-2b. Extreme caution should be exercised when didanosine and ribavirin are used concomitantly because of the increased risk of mitochondrial toxicity and the syndrome of severe metabolic acidosis with elevated lactic acid levels.
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PMID:Fatal lactic acidosis and pancreatitis associated with ribavirin and didanosine therapy. 1288 53

In the absence of antiviral treatment, chronic hepatitis C virus (HCV) infection is a liver disease characterized by the development of necroinflammatory changes and progressive liver fibrosis, leading to cirrhosis, end-stage liver disease and hepatocellular carcinoma (HCC). The approval of ribavirin in combination therapy regimens with interferon (IFN) dramatically improved therapy. Another advance was the introduction of pegylated IFNs, which allow a once-weekly subcutaneous administration and show more favorable pharmacokinetics and greater efficacy. Two forms are available: pegylated IFN alpha-2b (12 kDa) (1.5 microg/kg) and pegylated IFN alpha-2a (40 kDa) (fixed dosage of 180 microg). Ribavirin is administered orally, at doses > or =10.6 mg/kg, resulting in higher sustained virological responses (SVR) than IFN monotherapy. The highest SVR rates are attained with pegylated IFNs in combination with ribavirin. Factors associated with treatment outcome include HCV genotype, viral load, body weight, age, cirrhosis or bridging fibrosis, coinfection with HIV or hepatitis B virus, and treatment adherence and tolerance. Currently, the main therapeutic challenges ahead are: (a) the dosage optimization of pegylated IFNs and ribavirin according to the patients' characteristics; and (b) to evaluate the efficacy and safety of this combination therapy for difficult-to-treat patients, such as nonresponders, cirrhotics, transplant recipients, renal disease patients or those coinfected with HIV.
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PMID:Combined antiviral options for the treatment of chronic hepatitis C. 1463 10

The introduction of highly active anti-retroviral therapy (HAART) for Human Immunodeficiency Virus (HIV) infection has significantly improved the life expectancy of HIV positive patients. Hepatitis C virus (HCV) co-infection is common in HIV infected patients and is now a significant cause of morbidity and mortality. Optimal management and treatment of HCV in HIV infected patients is therefore essential. Interferon-alpha (IFN-alpha) and ribavirin is the mainstay of treatment for HCV infection in HIV infected people. The sustained virological response rate (SVR) with combination therapy is lower than that commonly observed in HCV mono-infected patients. This is, at least in part, due to the very high treatment drop out rates. Ribavirin in combination with HAART is associated with particular side effects such as mitochondrial toxicity. Therefore, vigilant monitoring of patients during therapy, in specialist centers is essential. Pegylated interferon (PEG-IFN) plus ribavirin is particularly promising as it is easier to administer and will probably become the treatment of choice for co-infected patients. A SVR is associated with genotype 2 and 3, in addition to a high CD4+ cell count and a low HCV load prior to therapy. The progression of HCV related liver disease in HIV positive patients is faster than in subjects with HCV infection alone. As a result, there is an increasing incidence of cirrhosis and end-stage liver disease in co-infected patients. Liver transplantation is being evaluated in many centers. To date the experiences are very limited but encouraging in term of survival rate.
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PMID:Therapy of chronic hepatitis C virus infection in HIV co-infected people. 1527 50

Pegylated interferon plus ribavirin is the standard first-line treatment in patients with chronic hepatitis C virus (HCV) mono-infection. Although the optimal anti-HCV regimen is not established in the more difficult-to-treat population with HIV-HCV co-infection, much of the data in this clinical setting have been derived from studies evaluating peginterferon-alpha-2a (40kD) [Pegasys] plus ribavirin (Copegus), most notably the APRICOT (AIDS Pegasys Ribavirin International Co-Infection Trial) and the ACTG (AIDS Clinical Trial Group) A5071 study. In particular, results of APRICOT - the largest study conducted to date with a pegylated interferon plus ribavirin in patients with HIV-HCV co-infection - indicate that a substantial proportion of patients will achieve sustained virological response (SVR) at week 72 when these drugs are administered for 48 weeks in an appropriate dosage regimen. In general, the tolerability profile of peginterferon-alpha-2a plus ribavirin in APRICOT was similar to that previously reported in patients with HCV mono-infection.
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PMID:Peginterferon-alpha-2a (40kD) plus ribavirin: a review of its use in hepatitis C Virus And HIV co-infection. 1556 53

The hepatitis C virus (HCV) is a major cause of chronic liver disease worldwide, with approximately 170-200 million people infected. The HCV virus is transmitted by blood and blood products and such transmission occurs primarily through drug use by injection, sex with an infected partner and occupational exposure. The severity of the disease varies widely from mild chronic hepatitis to cirrhosis and hepatocellular carcinoma (HCC). Nowadays, the reference treatment is combination therapy of pegylated interferon and ribavirin, which is an inosine monophosphate dehydrogenase inhibitor and immunomodulator. Efficacy of treatment in our clinical trials is 87% in patients infected by HCV genotypes 2 or 3, whereas in patients infected by HCV genotype 1 response to treatment is 66%. The current combination treatment has significant side-effects and sometimes is poorly tolerated. HCV genotypes 2 or 3 can be treated with a lower dose of ribavirin and a shorter course of therapy, 24 weeks vs 48 weeks for patients with genotype 1. There is a growing consensus that acute control of HCV infection is associated with a vigorous intrahepatic antiviral CD4+ and CD8+ T-cell response, enhanced Th1 and natural killer activity. Pretreatment genotype and response to therapy measured at weeks 12 and 24 of treatment have been identified as key determinants in decisions about continuing treatment. Elevated serum ferritin levels and hepatic iron deposition as well as hepatic steatosis and high ALT levels with chronic hepatitis C are risk factors for HCC development. Heterozygosityfor the C282Y mutation in HFE contributes to iron accumulation and fibrosis progression in chronic hepatitis C. Ribavirin could cause dose-dependent reversible haemolytic anaemia, which can be managed with dose reductions or with administration of epoetin alpha at 40,000 IU once weekly without sacrificing the optimal dosing of ribavarin. Among patients who received ribavirin alone, serum ALT levels and necroinflammatory features of liver histology were improved, whereas symptoms, HCV RNA levels and hepatic fibrosis scores were not changed significantly from baseline. For HCV-HIV co-infected patients, treatment is given when blood CD4 counts are above 350/ml and before antiretroviral (ART) treatment is needed.
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PMID:Ribavirin in the treatment of hepatitis C. 1586 84

Ribavirin (RBV) in combination with pegylated interferon alpha (pegIFN) is currently the standard treatment of hepatitis C virus (HCV) infection. The development of anemia requires a reduction in RBV doses in a substantial proportion of patients, limiting their chances of treatment response. The primary goal of this study was to assess if early monitoring of RBV plasma levels could help to predict anemia as well as early HCV RNA response in HIV/HCV-coinfected individuals. The secondary goal was to evaluate if antiretroviral drugs might influence RBV plasma levels. Plasma RBV concentrations were measured at weeks 4 and 12 in 98 HIV/HCV-coinfected individuals who initiated therapy with pegIFN-2a (180 microg/wk) plus RBV (800-1200 mg/d). RBV plasma levels correlated with RBV dose per kilogram of body weight (P = 0.02). Larger drops in hemoglobin levels were independently associated with higher RBV plasma levels and zidovudine (ZDV) use (P < 0.001). Likewise, higher RBV levels (P = 0.007) and HCV genotype 3 (P < 0.001) were found to be independent predictors of virologic response at week 4. Similar findings were obtained at week 12. Patients receiving ZDV concomitantly showed significantly higher RBV plasma concentrations compared with those who did not (3.28 mug/mL vs. 2.51 mug/mL; P = 0.002). RBV levels were not significantly altered by the coadministration of other nucleoside/nucleotide analogues. In summary, RBV plasma levels correlate with the development of anemia and with the achievement of an early virologic response. Therefore, early therapeutic drug monitoring might help to tailor RBV dosages, improving the efficacy and safety of anti-HCV treatment.
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PMID:Early monitoring of ribavirin plasma concentrations may predict anemia and early virologic response in HIV/hepatitis C virus-coinfected patients. 1601 Jan 60

The intracellular triphosphorylation and plasma pharmacokinetics of lamivudine (3TC), stavudine (d4T), and zidovudine (ZDV) were assessed in a pharmacokinetic substudy, in 56 human immunodeficiency virus-hepatitis C virus (HIV-HCV) coinfected patients receiving peginterferon alfa-2a (40KD) 180 microg/week plus either placebo or ribavirin (RBV) 800 mg/day in the AIDS PEGASYS Ribavirin International Coinfection Trial. There were no significant differences between patients treated with RBV and placebo in plasma pharmacokinetics parameters for the nucleoside reverse transcriptase inhibitors (NRTIs) at steady state (weeks 8 to 12): ratios of least squares mean of area under the plasma concentration-time curve (AUC(0-12 h)) were 1.17 (95% confidence interval, 0.91 to 1.51) for 3TC, 1.44 (95% confidence interval, 0.58 to 3.60) for d4T and 0.85 (95% confidence interval, 0.50 to 1.45) for ZDV, and ratios of least squares mean plasma C(max) were 1.33 (95% confidence interval, 0.99 to 1.78), 1.06 (95% confidence interval, 0.68 to 1.65), and 0.84 (95% confidence interval, 0.46 to 1.53), respectively. Concentrations of NRTI triphosphate (TP) metabolites in relation to those of the triphosphates of endogenous deoxythymidine-triphosphate (dTTP) and deoxcytidine-triphosphate (dCTP) were similar in the RBV and placebo groups. Differences (RBV to placebo) in least squares mean ratios of AUC(0-12 h) at steady state were 0.274 (95% confidence interval, -0.37 to 0.91) for 3TC-TP:dCTP, 0.009 (95% confidence interval, -0.06 to 0.08) for d4T-TP:dTTP, and -0.081 (95% confidence interval, -0.40 to 0.24) for ZDV-TP:dTTP. RBV did not adversely affect HIV-1 replication. In summary, RBV 800 mg/day administered in combination with peginterferon alfa-2a (40KD) does not significantly affect the intracellular phosphorylation or plasma pharmacokinetics of 3TC, d4T, and ZDV in HIV-HCV-coinfected patients.
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PMID:Effect of ribavirin on intracellular and plasma pharmacokinetics of nucleoside reverse transcriptase inhibitors in patients with human immunodeficiency virus-hepatitis C virus coinfection: results of a randomized clinical study. 1618 72

The adverse effects of antiviral drugs are dose dependent and often reversible. The major side effects include influenza-like symptoms, hematologic abnormalities and neuropsychiatric symptoms. The influenza-like syndrome can be prevented by paracetamol taken at the time of the injection. Psychiatric adverse effects range from irritability to a severe depressive syndrome. Antidepressants, such as selective serotonin reuptake inhibitors, may be useful in the management. Adverse hematologic effects can occur very early during treatment. The platelet count often stabilizes rapidly, but neutropenia can deteriorate throughout treatment. In selected patients treatment with hematopoietic growth factor (filgrastim) may be useful. Ribavirin therapy may result in a dose-dependent reversible intravascular hemolytic anemia in 10% of patients. Adjunctive therapy with erythropoietin for ribavirin-induced anemia is currently under evaluation. Interferons and ribavirin are contraindicated in pregnancy. Contraception must be continued for 4 months (women) and 7 months (men) after ribavirin cessation. Lactic acidosis may be a rare complication of combination therapy in patients undergoing therapy for HIV and HCV. Any sign of mitochondrial DNA depletion syndrome calls for blood lactate measurement and, possibly, a modification of antiretroviral treatment. Lamivudine is well tolerated but the emergence of lamivudine-resistant (YMDD) HBV mutants is associated with the loss of clinical response. Adefovir dipivoxil effectively suppresses lamivudine-resistant HBV in chronic hepatitis B.
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PMID:[Treatment of the side effects of antiviral therapy]. 1638 Dec 45

Infection of non-dividing cells is a biological property of HIV-1 crucial for virus transmission and AIDS pathogenesis. This property depends on nuclear import of the intracellular reverse transcription and pre-integration complexes (RTCs/PICs). To identify cellular factors involved in nuclear import of HIV-1 RTCs, cytosolic extracts were fractionated by chromatography and import activity examined by the nuclear import assay. A near-homogeneous fraction was obtained, which was active in inducing nuclear import of purified and labeled RTCs. The active fraction contained tRNAs, mostly with defective 3' CCA ends. Such tRNAs promoted HIV-1 RTC nuclear import when synthesized in vitro. Active tRNAs were incorporated into and recovered from virus particles. Mutational analyses indicated that the anticodon loop mediated binding to the viral complex whereas the T-arm may interact with cellular factors involved in nuclear import. These tRNA species efficiently accumulated into the nucleus on their own in a energy- and temperature-dependent way. An HIV-1 mutant containing MLV gag did not incorporate tRNA species capable of inducing HIV-1 RTC nuclear import and failed to infect cell cycle-arrested cells. Here we provide evidence that at least some tRNA species can be imported into the nucleus of human cells and promote HIV-1 nuclear import.
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PMID:tRNAs promote nuclear import of HIV-1 intracellular reverse transcription complexes. 2007 83


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