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Antimicrobial Agents and Chemotherapy Feb 2002The elimination of viral covalently closed circular DNA (CCC DNA) from the nucleus of infected hepatocytes is an obstacle to achieving sustained viral clearance during...
The elimination of viral covalently closed circular DNA (CCC DNA) from the nucleus of infected hepatocytes is an obstacle to achieving sustained viral clearance during antiviral therapy of chronic hepatitis B virus (HBV) infection. The aim of our study was to determine whether treatment with adefovir, a new acyclic nucleoside phosphonate, the prodrug of which, adefovir dipivoxil, is in clinical evaluation, is able to suppress viral CCC DNA both in vitro and in vivo using the duck HBV (DHBV) model. First, the effect of adefovir on viral CCC DNA synthesis was examined with primary cultures of DHBV-infected fetal hepatocytes. Adefovir was administered for six consecutive days starting one day before or four days after DHBV inoculation. Dose-dependent inhibition of both virion release in culture supernatants and synthesis of intracellular viral DNA was observed. Although CCC DNA amplification was inhibited by adefovir, CCC DNA was not eliminated by antiviral treatment and the de novo formation of CCC DNA was not prevented by pretreatment of the cells. Next, preventive treatment of experimentally infected ducklings with lamivudine or adefovir revealed that both efficiently suppressed viremia and intrahepatic DNA. However, persistence of viral DNA even when detectable only by PCR was associated with a recurrence of viral replication following drug withdrawal. Taken together, our results demonstrate that adefovir is a potent inhibitor of DHBV replication that inhibits CCC DNA amplification but does not effectively prevent the formation of CCC DNA from incoming viral genomes.
Topics: Adenine; Animals; Antiviral Agents; DNA, Circular; DNA, Viral; Disease Models, Animal; Ducks; Hepatitis B; Hepatitis B Virus, Duck; Hepatocytes; Organophosphonates
PubMed: 11796353
DOI: 10.1128/AAC.46.2.425-433.2002 -
Alimentary Pharmacology & Therapeutics Jun 2012Adefovir and tenofovir are nucleotide analogues used as long-term therapy of chronic hepatitis B. Side effects are few, but prolonged and high-dose therapy has been...
BACKGROUND
Adefovir and tenofovir are nucleotide analogues used as long-term therapy of chronic hepatitis B. Side effects are few, but prolonged and high-dose therapy has been associated with proximal renal tubular dysfunction (RTD).
AIM
To assess the incidence of RTD during long-term nucleotide therapy of chronic hepatitis B.
METHODS
A total of 51 patients being treated at the Clinical Center, National Institutes of Health were studied. Diagnosis of RTD required de novo appearance of at least three of five features: hypophosphataemia, hypouricaemia, serum creatinine elevation, proteinuria or glucosuria.
RESULTS
Among 51 patients treated for 1-10 (mean 7.4) years with adefovir (n = 42), tenofovir (n = 4) or adefovir followed by tenofovir (n = 5), 7 (14%) developed RTD. Time to onset ranged from 22 to 94 (mean 49) months with an estimated 10-year cumulative rate of 15%. All seven had low urinary percent maximal tubular reabsorption of phosphate (<82%). Patients with RTD were older (58 vs. 44 years; P = 0.01) and had lower baseline glomerular filtration rates (82 vs. 97 cc/min; P = 0.08) compared to those without; but did not differ in other features. Six patients with RTD were switched to entecavir, all subsequently had improvements in serum phosphate (2.0-3.0 mg/dL), creatinine (1.6-1.1 mg/dL), uric acid (2.7-3.8 mg/dL) and proteinuria.
CONCLUSIONS
Renal tubular dysfunction develops in 15% of patients treated with adefovir or tenofovir for 2-9 years and is partially reversible with change to other antivirals. Monitoring for serum phosphate, creatinine and urinalysis is prudent during long-term adefovir and tenofovir therapy.
Topics: Adenine; Adult; Aged; Antiviral Agents; Biomarkers; Creatinine; Female; Glomerular Filtration Rate; Hepatitis B, Chronic; Humans; Kidney Tubules; Male; Middle Aged; Organophosphonates; Phosphates; Renal Insufficiency; Tenofovir; Time Factors; Uric Acid
PubMed: 22506503
DOI: 10.1111/j.1365-2036.2012.05093.x -
Journal of Chromatographic Science 2009A selective and sensitive high-performance liquid chromatography-electrospray-tandem mass spectrometry method (HPLC-ESI-MS-MS) has been developed for the determination...
A selective and sensitive high-performance liquid chromatography-electrospray-tandem mass spectrometry method (HPLC-ESI-MS-MS) has been developed for the determination of adefovir in human plasma using adenine (PMPA) as an internal standard. After protein precipitation with methanol, the plasma sample was separated by HPLC on a reversed-phase XTerra MS/MS C(18) column (100 mm x 2.1 mm i.d., 3.5 mm) with a mobile phase of methanol-water (20:80, v/v). Standard curves were linear (r(2) = 0.9962) over the concentration range of 0.20-100 ng/mL and had acceptable accuracy and precision. The intra- and inter-batch precisions were within 11.30%. The lower limit of quantification (LLOQ) was 0.20 ng/mL. The validated HPLC-ESI-MS-MS method has been used successfully to study the pharmacokinetics of adefovir in healthy Chinese volunteers. The following pharmacokinetic parameters were elucidated after administering a single dose of 10 mg, 20 mg, and 30 mg of adefovir dipivoxil. Peak plasma concentrations (C(max)) were (26.6 +/- 6.1), (55.7 +/- 16.2), and (70.2 +/- 11.8) ng/mL, respectively; time to C(max) (T(max)) were (1.5 +/- 0.6), (1.6 +/- 0.7), and (1.8 +/- 0.6) h, respectively; the area under the plasma concentration versus time curve from time 0 h to 36 h (AUC(0-36)) were (184.5 +/- 25.2), (379.3 +/- 61.8) and (556.5 +/- 86.7) ng/mL, respectively; mean residence times (MRT) were (8.9 +/- 0.9), (9.0 +/- 1.0), and (8.9 +/- 1.0) h, respectively; and the elimination half-life (t(1/2)) were (8.0 +/- 0.9), (7.5 +/- 0.8), and (7.5 +/- 0.9) h, respectively. The pharmacokinetic parameters can provide some information for clinical medication.
Topics: Adenine; Adolescent; Adult; China; Chromatography, Liquid; Female; Humans; Male; Organophosphonates; Spectrometry, Mass, Electrospray Ionization; Tandem Mass Spectrometry; Young Adult
PubMed: 19930801
DOI: 10.1093/chromsci/47.10.889 -
Selection and counterselection of the rtI233V adefovir resistance mutation during antiviral therapy.Journal of Clinical Microbiology Feb 2010Recently, we reported on three patients with chronic hepatitis B virus (HBV) infection for whom adefovir (ADF) therapy virologically failed, most likely due to a...
Recently, we reported on three patients with chronic hepatitis B virus (HBV) infection for whom adefovir (ADF) therapy virologically failed, most likely due to a preexisting rtI233V HBV polymerase mutation. Here, we describe two further patients with chronic HBV infection who were found to develop the rtI233V mutation after initiation of ADF therapy. These patients represent the first cases known so far in which the rtI233V ADF resistance mutation evolved under persistent HBV replication during HBV therapy with ADF. Interestingly, one of the previously described patients, who was initially successfully switched from ADF to tenofovir (TDF) and became virologically suppressed subsequently, experienced a moderate but remarkable rebound of HBV viremia after switching from TDF to entecavir, due to the emergence of renal toxicity. Thus, we provide evidence for the selection and counterselection of the rtI233V ADF resistance mutation during antiviral therapy.
Topics: Adenine; Adult; Amino Acid Sequence; Amino Acid Substitution; Antiviral Agents; Drug Resistance, Viral; Female; Guanine; Hepatitis B virus; Hepatitis B, Chronic; Humans; Male; Molecular Sequence Data; Mutation, Missense; Organophosphonates; Selection, Genetic; Sequence Alignment; Tenofovir; Treatment Failure; Viremia; Young Adult
PubMed: 20007398
DOI: 10.1128/JCM.01073-09 -
International Journal of Infectious... Mar 2010Long-term lamivudine (LAM) and adefovir (ADV) treatment has been found to induce the emergence of drug-resistant hepatitis B virus (HBV) in a significant number of...
OBJECTIVE
Long-term lamivudine (LAM) and adefovir (ADV) treatment has been found to induce the emergence of drug-resistant hepatitis B virus (HBV) in a significant number of patients with chronic hepatitis B (CHB) infection. The aim of our study was to evaluate the LAM and ADV mutations detected in our patient group.
MATERIALS AND METHODS
Twenty-four patients diagnosed with CHB were enrolled in this study. The patient group consisted of those who had received 6 months of treatment with interferon-alpha and who did not response to this therapy. Patients were evaluated based on virologic and serologic response to therapy, and were classified as responders or non-responders. The treatment of non-responders continued with LAM (3mg/kg/d, maximum 100mg/d). Due to a lack of response to treatment, ADV (10mg/g) was added to the treatment regimen of eight young adult patients. The mutations associated with HBV drug resistance were investigated using reverse hybridization methods and PCR.
RESULTS
The mutation studies indicated that 14 (58.4%) of the patients had resistance. Three patients developed ADV-associated mutations (A181T), one after 18 months of ADV; the other two had undergone 18 and 36 months of LAM therapy without ADV exposure. Although the average LAM treatment period of the patients with LAM resistance was longer than for those in whom no resistance was detected, no statistically significant difference was found.
CONCLUSIONS
HBV treatment with nucleoside analogues results in the development of mutant strains, leading to drug resistance. Therefore genotypic resistance testing is important in planning and monitoring HBV treatment.
Topics: Adenine; Adolescent; Antiviral Agents; Child; Drug Administration Schedule; Drug Resistance, Viral; Female; Genotype; Hepatitis B virus; Hepatitis B, Chronic; Humans; Lamivudine; Male; Mutation; Organophosphonates; Reverse Transcriptase Inhibitors; Time Factors; Young Adult
PubMed: 19665408
DOI: 10.1016/j.ijid.2009.04.002 -
Journal of Hepatology Aug 2005Mathematical analysis of viral kinetics during lamivudine-adefovir combination therapy has not yet been performed in patients with lamivudine-resistant hepatitis B. (Comparative Study)
Comparative Study
BACKGROUND/AIMS
Mathematical analysis of viral kinetics during lamivudine-adefovir combination therapy has not yet been performed in patients with lamivudine-resistant hepatitis B.
METHODS
In 8 patients with lamivudine-resistant hepatitis B, adefovir dipivoxil (10 mg/day) was added to ongoing lamivudine. Viral decay during the first 8 weeks of combination therapy was described by a biphasic model to determine the efficacy: epsilon, of blocking viral production, the clearance: c, of free virus, and the loss of infected cells: delta.
RESULTS
Median epsilon was 98%, median c was 0.7/day, and median delta was 0.07/day. No significant association was found between viral kinetic and baseline parameters and virologic and biochemical treatment response. When compared with viral kinetic constants reported for higher dose adefovir dipivoxil monotherapy, epsilon was lower (P=0.026) and delta was higher (P=0.008) in this study whereas c did not differ between both studies.
CONCLUSIONS
Although a recent study did not show any differences in the reduction of HBV DNA comparing monotherapy with adefovir dipivoxil to adefovir-lamivudine combination therapy in patients with lamivudine-resistant chronic hepatitis B, mathematical analysis of early viral kinetics suggests an additional effect of lamivudine on the infected cell loss during adefovir-lamivudine combination therapy.
Topics: Adenine; Adolescent; Adult; Antiviral Agents; DNA, Viral; Drug Resistance, Viral; Drug Therapy, Combination; Female; Follow-Up Studies; Hepatitis B e Antigens; Hepatitis B virus; Hepatitis B, Chronic; Humans; Lamivudine; Male; Middle Aged; Models, Theoretical; Mutation; Organophosphonates; Reverse Transcriptase Inhibitors; Treatment Outcome; Virus Replication
PubMed: 15964093
DOI: 10.1016/j.jhep.2005.02.037 -
Alimentary Pharmacology & Therapeutics May 2012Combination antiviral therapy holds the promise of increasing response rates while decreasing antiviral resistance, but has yet to be shown to be beneficial or necessary... (Comparative Study)
Comparative Study Randomized Controlled Trial
BACKGROUND
Combination antiviral therapy holds the promise of increasing response rates while decreasing antiviral resistance, but has yet to be shown to be beneficial or necessary in chronic hepatitis B.
AIM
To evaluate the benefit of combination therapy with adefovir and lamivudine versus adefovir alone in maintaining virological, biochemical and histological responses.
METHODS
Patients with chronic hepatitis B with and without previous lamivudine therapy were randomised to receive adefovir alone (10 mg/daily) or adefovir and lamivudine (100 mg/daily) for up to 192 weeks. Study endpoints were (i) maintained virological (HBV DNA <500 copies/mL), biochemical and histological response, (ii) loss of HBeAg and (iii) loss of HBsAg.
RESULTS
A total of 41 patients were enrolled, including 31 HBeAg -positive and 31 treatment-naïve subjects. 30 patients remained on assigned therapy at 192 weeks. The percentage of patients achieving a combined maintained response was higher in the combination than the monotherapy arm, both at week 48 (59% vs. 26%, P = 0.06) and 192 (68% vs. 31%, P = 0.03). At week 192, 76% of the combination vs. 36% of the monotherapy group had loss of HBeAg (P = 0.03). One patient receiving adefovir cleared HBsAg. Adefovir resistance developed in 6 of 19 (32%) monotherapy but none of 22 combination treated patients (P = 0.03).
CONCLUSIONS
Extended combination therapy with lamivudine and adefovir is associated with a high rate of long-term virological and biochemical response. Adefovir monotherapy appears to be less effective mainly because of poor initial response and the ultimate development of antiviral resistance (www.Clinical. Trials.gov NCT00023309).
Topics: Adenine; Adult; Antiviral Agents; Drug Resistance, Viral; Drug Therapy, Combination; Female; Hepatitis B Surface Antigens; Hepatitis B e Antigens; Hepatitis B, Chronic; Humans; Lamivudine; Male; Middle Aged; Organophosphonates; Treatment Outcome
PubMed: 22449251
DOI: 10.1111/j.1365-2036.2012.05059.x -
World Journal of Gastroenterology Aug 2011To evaluate virological response to adefovir (ADV) monotherapy and emergence of ADV-resistant mutations in lamivudine (LAM)-resistant chronic hepatitis B patients.
AIM
To evaluate virological response to adefovir (ADV) monotherapy and emergence of ADV-resistant mutations in lamivudine (LAM)-resistant chronic hepatitis B patients.
METHODS
Seventy-seven patients with documented LAM resistance who were treated with 10 mg/d ADV for > 96 wk were analyzed for ADV resistance.
RESULTS
At week 48 and 96, eight (10%) and 14 (18%) of 77 LAM-resistant patients developed the ADV-resistant strain (rtA181V/T and/or rtN236T mutations), respectively. Hepatitis B virus (HBV) DNA levels during therapy were significantly higher in patients who developed ADV resistance than in those who did not. Incidence of ADV resistance at week 96 was 11%, 8% and 6% among patients with complete virological response (HBV DNA level < 60 IU/mL); 0%, 5% and 19% among patients with partial virological response (HBV DNA level ≥ 60 to 2000 IU/mL); and 32%, 34% and 33% among patients with inadequate virological response (HBV DNA levels > 2000 IU/mL) at week 12, week 24 and week 48, respectively. HBV DNA levels > 2000 IU/mL at week 24 showed best performance characteristics in predicting ADV resistance.
CONCLUSION
Development of ADV resistance mutations was associated with HBV DNA levels, which could identify patients with LAM resistance who are likely to respond to ADV monotherapy.
Topics: Adenine; Adult; Antiviral Agents; DNA, Viral; Drug Resistance, Viral; Female; Hepatitis B virus; Hepatitis B, Chronic; Humans; Lamivudine; Male; Middle Aged; Mutation; Organophosphonates; Retrospective Studies
PubMed: 21941420
DOI: 10.3748/wjg.v17.i30.3526 -
Antimicrobial Agents and Chemotherapy Dec 2013Treatment strategies for entecavir (ETV)-resistant chronic hepatitis B (CHB) patients are not yet well established. The aim of this study was to evaluate overall...
Treatment strategies for entecavir (ETV)-resistant chronic hepatitis B (CHB) patients are not yet well established. The aim of this study was to evaluate overall antiviral efficacy and to compare the efficacy of combination therapy with adefovir (ADV) plus nucleoside analogues (lamivudine [LAM], telbivudine [LdT], or ETV) in patients infected with LAM- and ETV-resistant hepatitis B virus (HBV) variants. Virologic, biochemical, and serologic responses during combination therapy with ADV plus nucleoside analogues were assessed. Propensity score analysis was used to select a matched group of patients for the comparison of rescue therapy regimens. A total of 67 consecutive patients were analyzed. Complete virologic suppression was achieved in 27 patients. The overall cumulative incidence of complete virologic suppression at month 24 was 47.4%: 44.3% in the LAM or LdT plus ADV group and 51.4% in the group given ETV and ADV. There was no significant difference between these two groups (P = 0.234). The cumulative incidences of complete virologic suppression were still comparable between the two groups selected and matched using the propensity score model (P = 0.419). Virologic breakthrough was observed in 9 patients, and rtA181V substitution was newly detected in one patient. Hepatitis B e antigen (HBeAg) negativity and lower baseline HBV DNA level were associated with complete virologic suppression in univariate analysis. In multivariate analysis, lower baseline HBV DNA level remained an independent predictor. In conclusion, combination therapy with ADV plus nucleoside analogues fails to show sufficient antiviral efficacy in CHB patients with resistance to both LAM and ETV. Further study is warranted to evaluate the efficacy of a more potent tenofovir-based regimen in such patients.
Topics: Adenine; Adult; Aged; Female; Guanine; Hepatitis B virus; Hepatitis B, Chronic; Humans; Lamivudine; Male; Middle Aged; Organophosphonates; Retrospective Studies; Reverse Transcriptase Inhibitors; Treatment Outcome
PubMed: 24100506
DOI: 10.1128/AAC.01742-13 -
European Journal of Pharmaceutical... Jun 2012Effects of 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3), natural ligand of the VDR, on the fates of adefovir dipivoxil (P-gp substrate) and its metabolites, mono(POM)-PMEA...
Effects of 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3), natural ligand of the VDR, on the fates of adefovir dipivoxil (P-gp substrate) and its metabolites, mono(POM)-PMEA and adefovir (MRP4 substrate), were investigated in Caco-2 cells. After 1,25(OH)2D3-treatment, higher apical efflux of adefovir was observed after a 60 min incubation of adefovir divipoxil. Changes in these washout studies were predicted by a catenary model for the Caco-2 monolayer that described a higher MRP4 activity with 1,25(OH)2D3 treatment, as confirmed by Western blotting. Moreover, 1,25(OH)2D3 treatment (100 nM for 3 days) resulted in increased basolateral (B) to apical (A) (B-to-A) transport of adefovir dipivoxil but an unchanged A-to-B flux, rendering an elevated efflux ratio (EfR) (from 1.97 to 3.19). The EfR values in control and 1,25(OH)2D3-treated groups in these transport studies were reduced to 1.32 and 1.57, respectively, in the presence of verapamil (50 μM), the P-gp inhibitor. The B-to-A transport of the metabolite, adefovir, was increased in 1,25(OH)2D3-treated cells in the presence of verapamil, whereas the A-to-B and B-to-A transport of mono(POM)-PMEA remained unchanged. But the verapamil and 1,25(OH)2D3 treatments failed to alter rates of sequential metabolism of adefovir dipivoxil in cell lysate. The composite data established that 1,25(OH)2D3 treatment increased both P-gp and MRP4 transport activities without affecting the metabolism of adefovir dipivoxil by esterases. Moreover, an asymmetric appearance of metabolites, being higher with apical application, was observed. According to the catenary model, the asymmetry is suggestive that esterases are predominantly localized on the apical membrane and within the cell.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; ATP Binding Cassette Transporter, Subfamily G, Member 2; ATP-Binding Cassette Transporters; Adenine; Biological Transport; Caco-2 Cells; Cells, Cultured; Drug Interactions; Humans; Multidrug Resistance-Associated Proteins; Neoplasm Proteins; Organophosphonates; Permeability; Verapamil; Vitamin D
PubMed: 22387228
DOI: 10.1016/j.ejps.2012.02.018