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)

Because prevention of heterosexual HIV transmission is not always possible, it is important to develop effective strategies of postexposure prophylaxis (PEP). Since in vivo comparison of drug potency is difficult, we developed an in vitro model with cells resembling primary targets during sexual transmission: monocyte-derived dendritic cells (MO-DCs), Langerhans cells (MO-LCs), and resting autologous CD4(+) T cells. Nucleoside and nonnucleoside reverse transcriptase inhibitors (NRTIs and NNRTIs, respectively) were evaluated for their antiviral activity, when added immediately after infection or at a later time point. In parallel, their immune-suppressive effect was examined by measuring inhibition of mixed MO-DC/allogeneic CD4(+) T cell cultures. Most RTIs potently inhibited HIV replication, even if added 24 hr after infection (representing PEP). The sensitivity to antiretroviral drugs was similar in HIV-infected MO-DCs and MO-LCs, but decreased in cocultures with resting autologous CD4(+) T cells. The NNRTIs efavirenz and UC-781 as well as the NRTIs AZT, 3TC, and d4T showed a similar high potency in MO-DC plus autologous CD4(+) T cell cocultures as compared with CEM T cells, whereas their activity in phytohemagglutinin/interleukin 2 (PHA/IL-2)-activated CD4(+) T cells was lower. The dideoxynucleoside RTI abacavir as well as the phosphonates (R)-PMPA and PMEA were more active in infected MO-DCs as compared with either CEM T cells or PHA/IL-2 activated CD4(+) T cells. Infection in cocultures of MO-DCs and autologous CD4(+) T cells could be aborted in a proportion of the cultures, with high concentrations of PMEA and/or efavirenz, but not with AZT. Suppressive activity in mixed leukocyte cultures was observed only at very high concentrations of RTI. Our data suggest that cocultures of MO-DCs and autologous CD4(+) T cells can be used as a possible in vitro model to explore protocols for PEP after sexual HIV transmission.
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PMID:Activity of reverse transcriptase inhibitors in monocyte-derived dendritic cells: a possible in vitro model for postexposure prophylaxis of sexual HIV transmission. 1239 48

The acyclic nucleoside phosphonates HPMPC (cidofovir), PMEA (adefovir), and PMPA (tenofovir) have proved to be effective in vitro (cell culture systems) and in vivo (animal models and clinical studies) against a wide variety of DNA virus and retrovirus infections: cidofovir against herpesvirus (herpes simplex virus types 1 and 2 varicella-zoster virus, cytomegalovirus [CMV], Epstein-Barr virus, and human herpesviruses 6, 7, and 8), polyomavirus, papillomavirus, adenovirus, and poxvirus (variola virus, cowpox virus, vaccinia virus, molluscum contagiosum virus, and orf virus) infections; adefovir against herpesvirus, hepadnavirus (human hepatitis B virus), and retrovirus (human immunodeficiency virus types 1 [HIV-1] and 2 [HIV-2], simian immunodeficiency virus, and feline immunodeficiency virus) infections; and tenofovir against both hepadnavirus and retrovirus infections. Cidofovir (Vistide) has been officially approved for the treatment of CMV retinitis in AIDS patients, tenofovir disoproxil fumarate (Viread) has been approved for the treatment of HIV infections (i.e., AIDS), and adefovir dipivoxil (Hepsera) has been approved for the treatment of chronic hepatitis B. Nephrotoxicity is the dose-limiting side effect for cidofovir (Vistide) when used intravenously (5 mg/kg); no toxic side effects have been described for adefovir dipivoxil and tenofovir disoproxil fumarate, at the approved doses (Hepsera at 10 mg orally daily and Viread at 300 mg orally daily).
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PMID:Clinical potential of the acyclic nucleoside phosphonates cidofovir, adefovir, and tenofovir in treatment of DNA virus and retrovirus infections. 1455 87

9-[1-(Phosphonomethoxycyclopropyl)methyl]guanine (PMCG, 1), representative of a novel class of phosphonate nucleosides, blocks HBV replication with excellent potency (EC(50) = 0.5 microM) in a primary culture of HepG2 2.2.15 cells. It exhibits no significant cytotoxicity in several human cell lines up to 1.0 mM. It does not inhibit replication of human immunodeficiency virus (HIV-1) or herpes simplex virus (HSV-1) at 30 microM. Many purine base analogues of 1 also exhibit inhibitory activity against HBV, but at 30 microM, pyrimidine analogues do not. 1 is 4 times more potent than 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA), which was used as a positive control (EC(50) = 2.0 microM). The characteristic cyclopropyl moiety at the 2'-position of 1 was prepared by titanium-mediated Kulinkovich cyclopropanation. 1 was modified to give the orally available drug candidate, PMCDG Dipivoxil (2). Compound 2 exhibited excellent efficacy when administered at 5 mg per kg per day in a study with woodchucks infected with woodchuck hepatitis B virus (WHBV). Drug candidate 2 has successfully completed phase I clinical trials and is currently undergoing phase II clinical studies for evaluation of efficacy.
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PMID:A novel class of phosphonate nucleosides. 9-[(1-phosphonomethoxycyclopropyl)methyl]guanine as a potent and selective anti-HBV agent. 1513 64

Current prophylactic measures have greatly reduced recurrence rates of hepatitis B after liver transplantation. HBIG remains a critically important compound and although there is variability in dosing regimens and target anti-HBs levels, it is the backbone of recurrence prevention. Adjuvant therapies with nucleoside/nucleotide analogs alone have been limited by drug-resistant strains of HBV, but the armamentarium of these molecules continues to grow and hence the management of the post-LT HBV patient will evolve further. Currently lamivudine with HBIG remains an excellent option provided the patient has not developed resistance, especially in the pre-LT period. Adefovir is the drug of choice in that setting and perhaps the preferred drug in the pre-LT setting to allow the use of lamivudine post-LT. Further testing with tenofovir and newer compounds in development will expand these options. The use of multiple nucleoside analogs is an intriguing option, based on the HIV experience of reducing drug resistance and optimizing viral suppression, and will likely be further studied.
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PMID:Liver transplant and recurrent disease. 1548 50

The acyclic nucleoside phosphonates [HPMPC: cidofovir, Vistide; PMEA: adefovir dipivoxil, Hepsera; and PMPA: tenofovir, Viread] have proven to be effective in vitro (cell culture systems) and in vivo (animal models and clinical studies) against a wide variety of DNA virus and retrovirus infections, for example, cidofovir against herpesvirus [herpes simplex virus type 1 and 2, varicella-zoster virus, cytomegalovirus, Epstein-Barr virus, human herpesvirus type 6, 7 and 8), polyoma-, papilloma-, adeno- and poxvirus (variola virus, cowpox virus, vaccinia virus, molluscum contagiosum virus and orf) infections; adefovir against herpesvirus, hepadnavirus [human hepatitis B virus] and retrovirus [HIV type-1 and 2, simian immunodeficiency virus and feline immunodeficiency virus] infections; and tenofovir against both hepadna- and retrovirus infections. Cidofovir has been officially approved for the treatment of cytomegalovirus retinitis in AIDS patients, tenofovir disoproxil fumarate (Viread) for the treatment of HIV infections (i.e., AIDS) and adefovir dipivoxil for the treatment of chronic hepatitis B.
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PMID:Potential of acyclic nucleoside phosphonates in the treatment of DNA virus and retrovirus infections. 1548

Interferon alpha, lamivudine, and adefovir are the three drugs currently approved for the treatment of chronic hepatitis B virus (HBV). There are pros and cons associated with the use of each drug. Individualization of therapy, based upon factors such as patient comorbidities, response to prior therapies, and stage of disease, is recommended. Patients with abnormal liver enzymes, indices of active viral replication (HBV DNA positive hepatitis B early antigen positive) or evidence of necroinflammatory activity on liver biopsy, and compensated liver disease are potential candidates for treatment with interferon, lamivudine, or adefovir. Patients with abnormal liver enzymes, indices of active viral replication (HBV DNA positive HB(e)Ag positive), and decompensated liver disease are candidates for treatment with lamivudine or adefovir. Consideration of liver transplantation should occur concurrently. Interferon alpha treatment results in hepatitis B surface antigen loss and sustained suppression of HBV DNA replication in 30% to 40% of treated patients. Loss of HBsAg occurs in nearly 10% of patients and a higher than expected frequency of HBsAg loss occurs long-term. The main limitation of therapy is the side effects and the need for parenteral administration. Additionally, interferon therapy is not applicable to all patient groups. Lamivudine achieves HB(e)Ag seroconversion in 15% to 20% of patients treated for 12 months, but (HBsAg) loss is rare. Reduction in HBV DNA to undetectable levels (by hybridization assay) during treatment is nearly universal, and histologic improvement is seen in about 55% of patients. The main limitation of lamivudine therapy is the development of drug resistance, which occurs in 20% of patients after 12 months and increases with duration of therapy (55% at 3 years). Adefovir achieves HB(e)Ag seroconversion in 12% of patients treated for 12 months, but HBsAg loss is rare. An average 3.5 log reduction in HBV DNA levels is and histologic improvement occurs in 50% to 60% of patients. It is effective against both wild-type and lamivudine-resistant HBV. The risk of drug resistance is low and estimated to be approximately 2% to 3% after 2 years of treatment. Several new antiviral agents are currently under evaluation in clinical trials. In addition, there are two drugs (tenofovir and emtricitabine) that have been approved for HIV infection and that have anti-HBV activity. In the future, combination therapy for chronic HBV infection can be anticipated. Utilization of two or more anti-HBV drugs would be predicted to enhance efficacy and reduce the likelihood of emergence of drug resistance.
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PMID:Chronic Hepatitis B. 1552 14

Two new classes of lipophilic prodrugs of the antiviral active phosphonate 9-[2-phosphonomethoxyethyl]adenine (PMEA 1) have been prepared and were studied with regard to their hydrolysis properties and biological activity. A first series of compounds was prepared on the basis of the cycloSal nucleotide approach. Because of the surprisingly low hydrolysis stability of these cycloSal-PMEA derivatives, more stable derivatives have to be developed. Instead of using salicyl alcohol, in cycloAmb-PMEA derivatives 2-aminobenzyl alcohols were attached to PMEA 1. The latter compounds showed a considerably higher stability compared to the cycloSal counterparts. Stability studies revealed that all lipophilic prodrugs delivered PMEA selectively by chemical means. All compounds proved to be noninhibiting to acetyl- and butyrylcholinesterase, and some of the phosphonate diesters were found to be more active against HIV compared to the parent PMEA.
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PMID:cycloSal-PMEA and cycloAmb-PMEA: potentially new phosphonate prodrugs based on the cycloSal-pronucleotide approach. 1633 32

For the treatment of HBV/HIV-co-infection, study data on interferon-based therapy are very limited and insufficient to draw any specific conclusions. In contrast, data on HBV-polymerase inhibitors (lamivudine, adefovir, tenofovir) are available from controlled trials. Lamivudine is well tolerated and safe, however, development of HBV-resistance is frequent. Adefovir has a nephrotoxic potential and may at least theoretically induce antiretroviral resistance in HBV/HIV-patients treated with adefovir. Tenofovir has gastrointestinal side effects, is associated with hypophospatemia, which has not induced serious osteopenia so far and may have a nephrotoxic potential. For HCV/HIV-co-infection pegylated interferon alpha plus ribavirin is standard of care. Flu-like symptoms, fatigue and depressive mood changes are frequent. In patients with a history of neurotic or minor depression initiation of treatment with antidepressants before the start of interferon-based therapy should be considered. Weight loss may be pronounced in individual cases. A marked decrease in absolute, but not relative CD4 +/- cells is the rule, but no relevant increase in opportunistic infection was observed, and anaemia (<10 g/dl) is reported in up to 30% of patients. Neutropenia (< 1,000 cells/microl) is observed in up to 50% of the patients. Adverse events specific to the HCV/HIV-patient population as compared to HCV-mono-infected patients are the occurrence of hyperlactataemia/lactic acidosis and hepatic decompensation.
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PMID:Treatment of viral hepatitis in HIV-coinfected patients-adverse events and their management. 1635 79

More and more HIV-infected patients are treated for viral hepatitis, increasing interactions. HEPATITIS C: The concomitant use of didanosine and ribavirin increases the risk of mitochondrial toxicity, responsible for pancreatitis and/or lactic acidosis. Lactic acidosis is characterized by a high mortality rate. Thus, didanosine, but also stavudine, should not be co-administered with ribavirin. Cases of hepatic decompensation have been reported in cirrhotics concomitantly receiving ribavirin and didanosine. Thus, this co-admininistration should be contraindicated in patients with advanced liver fibrosis. Anemia is a frequent side effect of ribavirin. In patients with zidovudine-related anemia, this drug should be discontinued before prescribing ribavirin. Erythropoietin may help to improve the haemoglobin level. HEPATITIS B: Adefovir significantly decreases the plasma levels of saquinavir. Pancreatitis may occur with the co-administration of didanosine and tenofovir. Thus this co-administration should be avoided. Atazanavir concentrations are decreased when tenofovir is co-administered. Thus, atazanavir should be boosted with ritonavir, when combined with tenofovir. Atazanavir increases the concentrations of tenofovir, with the potential risk of increasing the adverse events of tenofovir, including renal disorders. Tenofovir area under the curve is increased if lopinavir-ritonavir are co-administered. The main interactions, with a fatal risk, are observed with didanosine, when co-administered with ribavirin (hepatitis C) or with tenofovir (hepatitis B). Anemia is frequent, but usually moderate, when zidovudine is co-administered with ribavirin. Other interactions are usually easy to manage.
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PMID:Antiviral hepatitis and antiretroviral drug interactions. 1636 Feb 31

The development of Viread (tenofovir disoproxil) for HIV and Hepsera (adefovir dipivoxil) for HBV presented many unique challenges. Unlike nucleosides and most conventional drugs, the parent acyclic nucleotide analogs are charged at physiologic pH and not suitable for oral administration which is highly desired in chronic therapies. Physicochemical properties, cellular permeation, renal toxicity, and bioavailability all had to be addressed during the development of these compounds. As a class, the acyclic nucleotides have long intracellular half-lives, allowing once-daily dosing, which provided the initial rationale for treatment of chronic viral diseases such as HIV and HBV. Prodrugs originally designed to deliver the parent acyclic nucleotide analog to the systemic circulation, also function to increase the tissue distribution and intracellular concentrations of the acyclic nucleotide diphosphate inside cells.
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PMID:Perspectives on the development of acyclic nucleotide analogs as antiviral drugs. 1683 73


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