Entecavir is a potent anti-HBV drug superior to lamivudine: experience from clinical trials in China

Pharmacokinetic Study of Nalbuphine in Surgical Patients Undergoing General Anesthesia with Varying Degrees of Liver Dysfunction

Purpose

This study aimed to characterize the pharmacokinetics of nalbuphine in patients undergoing general anesthesia with varying degrees of liver dysfunction.

Patients and Methods

Twenty-four patients were enrolled and divided into three cohorts based on liver function: normal liver function (n = 13), mild liver dysfunction (n = 5), and moderate/severe liver dysfunction (n = 6). During the induction of anesthesia, they received 15 mg of nalbuphine intravenously. Venous blood samples were collected from each patient. The plasma concentration of nalbuphine was determined using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The pharmacokinetic parameters of nalbuphine were calculated by non-compartmental analysis (NCA) using Phoenix WinNonlin software.

Results

Compared with the normal liver function group, the plasma elimination half-life (T_1/2) of nalbuphine was increased by approximately 33% in the moderate/severe liver dysfunction group (2.66 h vs 3.54 h, P<0.05), and the volume of distribution (V_d) increased by approximately 85% (100.08 L vs 184.95 L, P<0.05). Multivariate analysis revealed that weight and platelet were associated with clearance (CL); total bilirubin as an independent factor was associated with T_1/2, and weight associated with area under the curve (AUC_(0→∞)) independently.

Conclusion

The T_1/2, mean residence time, and V_d of nalbuphine in patients with moderate/severe liver dysfunction were prolonged or increased significantly compared with those in the normal liver function group. These data suggest that it may need to be used with caution when nalbuphine is administered to patients with moderate or severe liver dysfunction.

Correlation Between Serum Entecavir Concentration and Virological Response in Patients with Chronic Type B Hepatitis

Background

This study was conducted to investigate the relationship between trough concentrations of serum entecavir and the virological response of patients with chronic type B hepatitis (CHB).

Material/Methods

A total of 59 CHB patients who had been receiving antiviral therapy with entecavir for >3 months were included in this study. Serum entecavir concentrations, HBV DNA levels, and other biochemical indicators were determined after drug treatments.

Results

The serum entecavir concentrations in the good response and poor response groups were 0.58±0.38 and 0.43±0.15 ng/mL, respectively. The antiviral efficacy was 52.38%, 65.63%, and 100% in low, middle, and high entecavir groups, respectively. The baseline HBV DNA level among the patients with poor response was significantly higher than in the group with good response. Among the 14 patients with a high viral load, 5 patients showed a good response and had a higher entecavir concentration than the other 9 patients with poor response. Entecavir in patients with cirrhosis was higher than in those without cirrhosis (0.63±0.45 ng/mL vs. 0.46±0.16 ng/mL), and the virological response rate in patients with cirrhosis was higher than in those without cirrhosis (83.33 vs. 51.43%). Cirrhosis progression was reversed in 3 patients with high serum entecavir concentration.

Conclusions

Serum entecavir concentrations vary among individuals, and higher serum entecavir concentration is correlated with more efficient viral clearance. Therefore, for patients with poor response, high doses may be beneficial for viral clearance.

Pharmacokinetic Analysis of Propofol Target-Controlled Infusion Models in Chinese Patients with Hepatic Insufficiency

Background

Effects of liver dysfunction on target-controlled infusion (TCI) with Marsh parameters of propofol remain poorly documented. The purpose of this study was to evaluate the performance of propofol TCI in a cohort of Chinese patients with severe hepatic insufficiency.

Material/Methods

We assigned 32 patients who underwent liver transplantation to 3 groups according to Child-Turcotte-Pugh (CTP) score. Anesthesia, preceding liver transplantation, was induced and maintained with TCI of 3 μg/mL propofol. Plasma propofol concentration was assessed. Propofol TCI system performance was analyzed in terms of error size, bias, and divergence. Data on plasma propofol concentrations were analyzed, and population pharmacokinetic parameters of propofol were fitted by NONMEM software.

Results

In the CTP C group, measured concentrations of propofol were much higher than those of predictive concentrations, with significantly higher overshoots compared to CTP A patients. Overall, TCI system performance was significantly lower in CTP C patients. Linear regression equations of Cm vs. Cp and a regression model of pharmacokinetics were obtained.

Conclusions

Propofol TCI device performance with Marsh parameters was clinically acceptable in CTP A patients but may not be suitable for patients with severe hepatic impairment.

Reduced therapeutic effect of antiviral drugs in patients with hepatitis B virus reactivation after hematopoietic stem cell transplantation

AIM

Patients with resolved hepatitis B virus (HBV) infection following hematopoietic stem cell transplantation (HSCT) are potentially at high risk of HBV reactivation. Although antiviral drug therapy is recommended when HBV DNA reappears in the serum, drug efficacy after HBV reactivation remains unclear.

METHODS

Host immune response against HBV was investigated by immunological analyses at 12 months after entecavir (ETV) treatment in six HSCT-treated and five non-HSCT-treated patients with HBV reactivation, and 18 patients with chronic hepatitis B (CHB). Peripheral HBV-specific CD8⁺ T cells were analyzed for total numbers by flow cytometry and tetramer staining, as was intracellular γ-interferon (IFN-γ) production and CD107a expression in response to HBV peptides. Interleukin-10 (IL-10)-expressing CD19⁺ B-cell count and serum inflammatory cytokine levels were also analyzed.

RESULTS

Serum HBV DNA was detectable in HSCT-treated patients with HBV reactivation at 12 months compared with other groups, indicating insufficient ETV efficacy against HBV. The HBV-specific CD8⁺ T-cell counts in HSCT-treated patients with HBV reactivation were significantly lower compared with those in non-HSCT patients. Additionally, IFN-γ production and CD107a expression by CD8⁺ T cells after incubation with HBV peptides was significantly reduced in HSCT-treated compared with CHB patients at 12 months after ETV treatment. Conversely, HSCT-treated patient serum IL-10 levels were significantly elevated compared with those in non-HSCT patients. Finally, IL-10-producing CD19⁺ B-cell counts were increased in HSCT-treated compared with CHB patients.

CONCLUSION

After HBV reactivation, ETV efficacy was impaired in HSCT-treated patients as evidenced by low HBV-specific CD8⁺ T-cell counts and high B-cell IL-10 production.

Lamivudine improves short-term outcome in hepatitis B virus-related acute-on-chronic liver failure patients with a high model for end-stage liver disease score

AIM

Hepatitis B virus (HBV)-related acute-on-chronic liver failure (ACLF) has significant morbidity and mortality. There is no standard approach for the management of HBV-related ACLF with nucleos(t)ide analogs. Our objective was to compare the short-term mortality between entecavir (ETV) and lamivudine (LAM) in patients with HBV-related ACLF.

METHODS

We recruited 311 inpatients with HBV-related ACLF from December 2002 to January 2015. The patients were treated with ETV (n=143) or LAM (n=168). The primary endpoint was mortality rate at week 8. Virological and biochemical responses were also studied.

RESULTS

By week 8, 53 (37.06%) patients in the ETV group and 57 (33.93%) patients in the LAM group died, and the two groups had similar mortality (P=0.414). Multivariate analysis showed that age, total bilirubin, international normalized ratio, and model for end-stage liver disease (MELD) score were independent factors for mortality at week 8. The best cut-off value of the MELD score was 24.5 for 8-week mortality. Twenty-nine of the 170 (17.06%) patients with MELD score less than 24.5 died at week 8, and the ETV and LAM groups had similar mortality (P=0.743). Eighty-one of the 141 (57.45%) patients with MELD score of at least 24.5 died at week 8 and the LAM group had lower mortality than the ETV group (P=0.018 at week 4; P=0.039 at week 8). Both groups showed similar virological and biochemical responses at 4 weeks.

CONCLUSION

LAM reduces the 8-week mortality rate significantly in patients with HBV-related ACLF who had MELD score of at least 24.5.

Efficacy of entecavir treatment for up to 96 weeks in nucleoside-naive HBeAg-positive chronic hepatitis B patients with high viral load

BACKGROUND AND AIMS

To evaluate the antiviral response of hepatitis B e antigen (HBeAg)-positive chronic hepatitis B (CHB) patients who had baseline high viral load (HVL), defined as having hepatitis B virus (HBV) DNA>9log 10 copies/mL, after 96weeks of entecavir (ETV) treatment.

METHODS

A total of 99 HBeAg-positive CHB patients (50 with HVL and 49 with non-HVL) were treated with ETV monotherapy for 96weeks.

RESULTS

Virological response (VR) (HBVDNA<300copies/mL) was achieved in 42%, 62%, 68% of HVL patients and in 67.34%, 85.71%, 85.71% of non-HVL patients at weeks 48,72,96, respectively. The VR rates of the HVL group were lower than those of the non-HVL group (P=0.006, P=0.007, and P=0.037). In the HVL group, a total of 30 patients had HBV DNA<1000copies/mL at week 48 and those patients had a 93.3% chance of achieving VR at week 96, whereas the patients who had HBV DNA levels>1000copies/mL at week 48 only had a 30% chance to achieve VR at week 96. Among the 96weeks of treatment, one patient had virological breakthrough in the HVL group and this patient had HBVDNA>1000copies/mL at week48. The rates of biochemical responses (BR) and HBeAg seroconversion (SR) were similar between the HVL group and non-HVL group at weeks 48 and 96.

CONCLUSION

The baseline HVL was a negative predictor of virological response in CHB patients with ETV monotherapy. For those HVL patients treated by ETV with poor VR, which defined as HBVDNA>1000copies/mL at week48, the treatment strategies need to be adjusted.

Entecavir vs lamivudine therapy for naïve patients with spontaneous reactivation of hepatitis B presenting as acute-on-chronic liver failure

AIM: To investigate the short-term and long-term efficacy of entecavir versus lamivudine in patients with spontaneous reactivation of hepatitis B presenting as acute-on-chronic liver failure (ACLF).

METHODS: This was a single center, prospective cohort study. Eligible, consecutive hospitalized patients received either entecavir 0.5 mg/d or lamivudine 100 mg/d. All patients were given standard comprehensive internal medicine. The primary endpoint was survival rate at day 60, and secondary endpoints were reduction in hepatitis B virus (HBV) DNA and alanine aminotransferase (ALT) levels, and improvement in Child-Turcotte-Pugh (CTP) and model for end-stage liver disease (MELD) scores at day 60 and survival rate at week 52.

RESULTS: One hundred and nineteen eligible subjects were recruited from 176 patients with severe acute exacerbation of chronic hepatitis B: 65 were included in the entecavir group and 54 in the lamivudine group (full analysis set). No significant differences were found in patient baseline clinical parameters. At day 60, entecavir did not improve the probability of survival (P = 0.066), despite resulting in faster virological suppression (P < 0.001), higher rates of virological response (P < 0.05) and greater reductions in the CTP and MELD scores (all P < 0.05) than lamivudine. Intriguingly, at week 52, the probability of survival was higher in the entecavir group than in the lamivudine group [42/65 (64.6%) vs 26/54 (48.1%), respectively; P = 0.038]. The pretreatment MELD score (B, 1.357; 95%Cl: 2.138-7.062; P = 0.000) and virological response at day 30 (B, 1.556; 95%Cl: 1.811-12.411; P =0.002), were found to be good predictors for 52-wk survival.

CONCLUSION: Entecavir significantly reduced HBV DNA levels, decreased the CTP and MELD scores, and thereby improved the long-term survival rate in patients with spontaneous reactivation of hepatitis B presenting as ACLF.

Clinical utility of entecavir for chronic hepatitis B in Chinese patients

The People's Republic of China has one of the highest rates of hepatitis B virus (HBV) infection. This review summarizes recent data from studies of entecavir, one of the recommended first-line oral therapies for treating chronic hepatitis B, in Chinese HBV-infected patients. Long-term treatment with entecavir is efficacious and well tolerated, and studies comparing entecavir with other nucleos(t)ide therapies, such as lamivudine, adefovir, and telbivudine, demonstrate superior antiviral effects for entecavir therapy and comparable safety profiles. Entecavir monotherapy and combination treatment with other nucleos(t) ide analogs has been shown to be efficacious in the treatment of lamivudine-resistant and adefovir-resistant patients with HBV infection, as well as in patients with multidrug-resistant disease. Entecavir has also been shown to be effective in patients with HBV-associated clinical morbidity, including cirrhosis and liver failure, as well as in preventing recurrence of HBV following liver transplantation and in preventing reactivation of HBV after immunosuppres-sive therapy. Although the cost of anti-HBV therapy is a particular concern in the People's Republic of China, a number of studies have recently demonstrated that entecavir (particularly long-term therapy) represents a more cost-effective treatment strategy compared with other nucleos(t)ide therapies. Further research is required to assess the effects of entecavir combination therapy on hepatitis B surface antigen clearance, and in drug-resistant patients in the People's Republic of China.

LC-MS/MS method for the characterization of the forced degradation products of Entecavir

A rapid, specific, and reliable isocratic LC-MS/MS method has been developed and validated for the identification and characterization of the stressed degradation products of Entecavir (ETV). ETV, an antiviral drug, was subjected to hydrolysis (acidic, alkaline, and neutral), oxidation, photolysis and thermal stress, as per the international conference on harmonization specified conditions. The drug showed extensive degradation under oxidative and acid hydrolysis stress conditions. However, it was stable to thermal, acidic, neutral, and photolysis stress conditions. A total of five degradation products were observed and the chromatographic separation of the drug and its degradation products were achieved on a Waters Symmetry C18 (250 mm × 4.6 mm, id, 5 μm) column using 20 mM ammonium acetate (pH 3)/acetonitrile (50:50, v/v) as a mobile phase. The degradation products were characterized by LC-MS/MS and its fragmentation pathways were proposed. The LC-MS method was validated with respect to specificity, linearity, accuracy, and precision. No previous reports were found in the literature regarding the degradation behavior of ETV.

Cost effectiveness of first-line oral antiviral therapies for chronic hepatitis B : a systematic review

BACKGROUND

Chronic hepatitis B is a common, progressive disease, particularly when viral replication is detected. Oral antivirals can suppress viral replication and prevent or delay the development of cirrhosis and liver-related complications.

OBJECTIVE

The aim of this study was to systematically review the quality of cost-effectiveness evidence on first-line treatment with entecavir (ETV) or tenofovir difumarate (TDF) for patients with chronic hepatitis B.

METHODS

We searched electronic databases and retrieved articles published up to October 2011, in which the cost effectiveness of ETV or TDF was compared with that of other oral antivirals. The quality of the studies identified was assessed with a standard checklist for critical appraisal.

RESULTS

We selected 16 original papers, all published in the last 5 years. There was a conflict of interest in 12 of the 16 studies due to sponsorship by the corresponding pharmaceutical companies. According to the validity assessment, ten studies were classified as high quality. Five studies performed a cost-effectiveness analysis comparing ETV with TDF; they concluded that TDF dominates ETV. The other 11 studies compared ETV or TDF with other strategies; all concluded that ETV and TDF are both cost-effective interventions.

CONCLUSIONS

This systematic review shows that there is valid evidence suggesting that ETV and TDF are cost-effective interventions for the treatment of patients with chronic hepatitis B in many health systems. In countries where both alternatives are available, it appears that TDF dominates ETV. These results could help decision makers and clinicians to understand economic issues regarding the available drugs for first-line treatment of hepatitis B.

Entecavir and lamivudine therapy for severe acute chronic hepatitis B

Severe acute exacerbation in patients with chronic hepatitis B is a unique clinical presentation that results in high mortality. To compare the efficacy of 4 weeks of entecavir or lamivudine therapy in patients with severe acute exacerbation caused by chronic hepatitis B, 65 patients were retrospectively analyzed. The groups received 0.5 mg entecavir (group A) or 100 mg lamivudine (group B) daily. After 4 weeks of treatment, virological and biochemical responses and the deterioration rates were determined. The average age and alanine aminotransferase (ALT), bilirubin, albumin, creatinine (Cr), and HBV DNA levels were similar in groups A and B prior to treatment, but the prothrombin time (PT) was shorter in group A. Following treatment, ALT and bilirubin levels were improved while there were no significant changes in PT, albumin or Cr levels at week 4 in group B. Only ALT was markedly upregulated following treatment in group A. There were no significant differences between the virological and biochemical responses or the deterioration rates of the two groups. These results suggested that short-term treatment with lamivudine markedly alleviated the increased bilirubin (TB) levels in patients with severe acute exacerbation of chronic hepatitis B and that there was no significant difference in the deterioration rate between patients treated by the two types of medication.

What MELD score mandates use of entecavir for ACLF-HBV HBeAg-negative patients?

AIM: To investigate optimal timing for therapeutic efficacy of entecavir for acute-on-chronic hepatitis B liver failure (ACLF-HBV) in hepatitis B e antigen (HBeAg)-negative patients.

METHODS: A total of 109 inpatients with ACLF-HBV were recruited from the Department of Infectious Diseases of the Third Affiliated Hospital, Sun Yat-sen University from October 2007 to October 2010. Entecavir 0.5 mg/d was added to each patient’s comprehensive therapeutic regimen. Patients were divided into three groups according to model for end-stage liver disease (MELD) score: high (≥ 30, 20 males and 4 females, mean age 47.8 ± 13.5 years); intermediate (22-30, 49 males and 5 females, 45.9 ± 12.4 years); and low (≤ 22, 28 males and 3 females, 43.4 ± 9.4 years). Statistical analysis were performed using SPSS 11.0 software. Data with normal distribution were expressed as mean ± SD and comparisons were made with Student’s t tests. A value of P < 0.05 was considered statistically significant. Viral loads were related exponentially and logarithmic data were used for analysis.

RESULTS: For 24 patients with MELD score ≥ 30, treatment lasted 17.2 ± 16.5 d. Scores before and after treatment were significantly different (35.97 ± 4.87 and 40.48 ± 8.17, respectively, t = -2.762, P = 0.011); HBV DNA load was reduced (4.882 ± 1.847 copies log₁₀/mL to 3.685 ± 1.436 copies log₁₀/mL); and mortality rate was 95.83% (23/24). Of 54 patients with scores of 22-30, treatment lasted for 54.0 ± 43.2 d; scores before and after treatment were 25.87 ± 2.33 and 25.82 ± 13.92, respectively (t = -0.030, P = 0.976); HBV DNA load decreased from 6.308 ± 1.607 to 3.473 ± 2.097 copies log₁₀/mL; and mortality was 51.85% (28/54). Of 31 patients with scores ≤ 22, treatment lasted for 66.1 ± 41.9 d; scores before and after treatment were 18.88 ± 2.44 and 12.39 ± 7.80, respectively, (t = 4.860, P = 0.000); HBV DNA load decreased from 5.841 ± 1.734 to 2.657 ± 1.154 copies log₁₀/mL; and mortality was 3.23% (1/31).

CONCLUSION: For HBeAg-negative patients with ACLF-HBV, when entecavir was added to comprehensive therapy, a MELD score ≥ 30 predicted very poor prognosis due to fatal liver failure.

Economic analysis between entecavir and lamivudine for the treatment of chronic hepatitis B in Hong Kong

BACKGROUND AND AIM

Tremendous healthcare resources have been spent on the management of chronic hepatitis B (CHB) and its related complications. Therefore, a proper evaluation of the cost-effectiveness of pharmacotherapy is vital in aid of decision-making. The aim of the present study was to examine the long-term economic and clinical influence if lamivudine was replaced by entecavir in a group of CHB patients.

METHODS

A recently published decision analytic model was adapted to study the cost-effectiveness of 2 years of treatment of entecavir in a hypothetical cohort of 1000 hepatitis B e antigen (HBeAg)-negative CHB patients from a public hospital perspective. Compensated cirrhosis (CC) and de-compensated cirrhosis (DC) and hepatocellular carcinoma (HCC) events were projected to 10 years. Hong Kong-specific health care costs were used. Quality Adjusted Life Years (QALYs) were calculated using the utility values obtained from a local study.

RESULTS

In the base case analysis, compared with lamivudine, the use of entecavir was expected to reduce the incidences of CC, DC and HCC by 41.8%, 57.1% and 49.3%, respectively, and lead to a saving of $US 1.17 million in medical cost. The overall disease management cost for entecavir, which was 67.7% higher than lamivudine for 2 years treatment was reduced to 17.2% after projecting 2-year treatment duration to 10 years. The incremental cost per QALY gained for entecavir compared with lamivudine was $US 13 759.

CONCLUSIONS

Based on the recommended cost-effectiveness threshold of the World Health Organization, entecavir is considered cost-effective compared with lamivudine in treating CHB in Hong Kong when long term medical consequences were considered.

The management of chronic hepatitis B in Asian Americans

Hepatitis B virus (HBV) infection is common with major clinical consequences worldwide. In Asian Americans, the HBsAg carrier rate ranges from 7 to 16%; HBV is the most important cause of chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). Patients are first diagnosed at different stages of clinical disease, which is categorized by biochemical and virologic tests. Patients at risk for liver complications should be identified and offered antiviral therapy. The two antiviral agents recommended for first-line treatment of chronic hepatitis B (CHB) are entecavir and tenofovir. The primary goal of therapy is sustained suppression of viral replication to achieve clinical remission, reverse fibrosis, and prevent and reduce progression to end-stage liver disease and HCC. Asian patients with chronic hepatitis, either HBeAg-positive or -negative, with HBV DNA levels >10(4) copies/mL (>2,000 IU/mL) and alanine aminotransferase (ALT) values above normal are candidates for antiviral therapy. HBeAg-negative patients with HBV DNA >10(4) copies/mL (>2,000 IU/mL) and normal ALT levels but who have either serum albumin ≤3.5 g/dL or platelet count ≤130,000 mm(3), basal core promoter mutations, or who have first-degree relatives with HCC should be offered treatment. Patients with cirrhosis and detectable HBV DNA must receive antiviral therapy. Considerations for treatment include pregnant women with high viremia, coinfected patients, and those requiring immunosuppressive therapy. In HBsAg-positive patients with risk factors, lifelong surveillance for HCC with alpha-fetoprotein testing and abdominal ultrasound examination at 6-month intervals is required. These recommendations are based on a review of relevant literature and the opinion of a panel of Asian American physicians with expertise in hepatitis B treatment.

HBV DNA loss within 24 weeks predicts late viral breakthrough in chronic hepatitis B

BACKGROUND/AIMS

Sustained HBV DNA reduction is necessary for biochemical remission, histological improvement, and prevention of complications. We analyzed the time taken from HBV DNA loss to viral breakthrough after antiviral treatment in patients with chronic hepatitis B (CHB). The early fall of the HBV DNA level to undetectable levels assessed really whether it is related to late breakthrough.

METHODS

A total of 91 patients whose HBV DNA levels dropped below undetectable levels were chosen from lamivudine-treated 306 patients and were analyzed retrospectively. The patients were divided into 4 groups (A≤12, 12<B≤24, 24<C≤48, D>48 wk) according to the time taken for the HBV DNA to decrease below undetectable levels. HBV DNA level was determined every 3 months.

RESULTS

The mean time taken for loss of HBV DNA was 34±28 wk. The baseline ALT differed significantly among groups (A: 382±274, B: 340±30, C: 166±92, D: 54±100 IU/L) (p=0.007). Fifty nine of the 91 patients (64.8%) experienced viral breakthrough. The mean interval between HBV DNA loss and viral breakthrough was 65±40 wk and differed significantly between group A, B (82±43 wk) and group C, D (56±28 wk) (p=0.015). In multivariate analysis, only HBV DNA loss within 24 wk, was found to be independently associated with late viral breakthrough (p=0.035). Undetectable HBV DNA after 24 wk was associated with high odd ratio of 3.24 (95% CI, 1.09-9.67).

CONCLUSIONS

HBV DNA loss within 24 wk after antiviral treatment could predict the late breakthrough.

LC-ESI-MS/MS method for the quantification of entecavir in human plasma and its application to bioequivalence study

Liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) was used for a quantitative estimation of entecavir (EV) in human plasma using lamivudine (LM) as internal standard (IS). The method herein described is simple, sensitive, and specific. Chromatographic separation was performed on XBridge-C18, 4.6 mm × 50 mm, 5-μm column with an isocratic mobile phase composed of 10 mM ammonium hydrogen carbonate (pH 10.5):methanol (85:15 v/v), pumped at 0.3 ml/min. EV and LM were detected using proton adducts at m/z 278.1→152.1 and 230.2→112.0 in multiple reaction monitoring (MRM) positive mode. Solid phase extraction method was employed in the extraction of EV and LM from the biological matrix. This method was validated over a linear concentration range of 50.0-20000.0 pg/ml with a correlation coefficient (r) ≥0.9983. Intra and inter-day precision of EV was found within the range of 1.2-4.2 for EV and 4.4-4.5 for LM. EV was stable throughout three freeze/thaw cycles, bench top and postoperative studies. This method was successfully used in the analysis of plasma samples following oral administration of EV (0.5 mg) in 26 healthy human volunteers.

Antiviral treatment of chronic hepatitis B virus (HBV) infections

While 25 compounds have been formally licensed for the treatment of HIV infection (AIDS), only seven licensed products are currently available for the treatment of chronic hepatitis B virus (HBV) infection: interferon-α, pegylated interferon-α, lamivudine, adefovir (dipivoxil), entecavir, telbivudine and tenofovir (disoproxil fumarate). In contrast to the treatment of HIV infections where the individual drugs are routinely used in combination, for the treatment of chronic HBV infection the individual drugs are generally used in monotherapy. In principle, combination drug therapy should allow reducing the likelihood of drug-resistant development.

Entecavir: a review of its use in chronic hepatitis B

Entecavir (Baraclude), a nucleoside analogue, is rapidly phosphorylated to the active intracellular 5'-triphosphate form that inhibits replication of hepatitis B virus (HBV). Oral entecavir is approved in the US, EU and several countries worldwide for the treatment of chronic HBV infection in adults (> or =16 years of age) with evidence of active viral replication and persistently elevated serum ALT and/or AST levels, and/or histological evidence of active disease. In several randomized, double-blind, multicentre trials, oral entecavir was an effective and generally well tolerated treatment in nucleoside-naive and lamivudine-refractory adult patients with chronic HBV infection, irrespective of whether patients were hepatitis B e antigen (HBeAg)-positive or -negative. Furthermore, it was more efficacious, associated with a lower risk of resistance, and more cost effective than lamivudine in these patient populations, with both drugs having a similar tolerability profile. In the EARLY trial, entecavir was significantly more effective than and as well tolerated as adefovir dipivoxil therapy in nucleoside-naive patients. In addition, in a double-blind, multicentre trial, entecavir plus lamivudine-based highly active antiretroviral therapy (HAART) was more effective than placebo plus lamivudine-based HAART in patients co-infected with HBV and HIV. Although the exact position of entecavir relative to other agents, such as tenofovir disoproxil fumarate and adefovir dipivoxil, for the treatment of chronic HBV infection remains to be fully determined, an important aspect in this positioning is the emergence of drug resistance. Hence, entecavir therapy provides a valuable first-line option in nucleoside-naive patients with chronic HBV infection and is a useful alternative in lamivudine-refractory patients.

Spontaneous HBeAg seroconversion and loss of hepatitis B virus DNA after acute flare due to development of drug resistant mutants during entecavir monotherapy

AIMS

Patients with chronic hepatitis B virus (HBV) infection under entecavir (ETV) treatment develop resistant mutants with viral rebound. Here, we report an interesting case of spontaneous loss of HBV-DNA and seroconversion following an acute flare after the development of ETV-resistant mutants. This patient received ETV after lamivudine breakthrough.

METHODS

Cloning and sequence analysis of the HBV reverse transcriptase (RT) region were performed with seven samples during ETV therapy. In addition, two full-length HBV genomes derived from samples before and after the emergence of ETV resistance were sequenced.

RESULTS

ETV resistant mutants appeared at week 228, with virological and biochemical rebound at the same time. Unexpectedly, HBeAg seroconversion occurred 8 weeks later. The viral load decreased and became undetectable from week 252. Analysis of HBV isolates in the patient at week 124 revealed that wild-type HBV was predominant at that time and ETV resistant mutants were not found among 20 clones. Interestingly, a new mutant type with rtL180M+rtT184L was found alongside rtL180M+rtT184L+rtM204V/I at week 228 and appeared to develop independently, according to the sequence analysis. In contrast to the previously identified ETV resistant mutants, it did not carry the rtM204V/I mutations.

CONCLUSION

The data presented here indicates that the flare following the emergence of ETV resistant mutants may reflect immune-mediated control of HBV infection, leading to a spontaneous loss of HBV-DNA and seroconversion.

[Entecavir]

Chronic hepatitis B continues to be a serious problem worldwide. Because a high viral load is associated with greater progression to cirrhosis and hepatocarcinoma in these patients, new drugs that achieve rapid, potent and lasting suppression of viral replication must be sought. Entecavir is a new, highly potent antiviral agent; phase II and III studies have demonstrated this drug to be superior to placebo and lamivudine in patients with chronic hepatitis B virus in terms of histological improvement, efficacy in achieving suppression of viral replication and normalizing transaminase counts. The drug is well tolerated, since its adverse effects are usually mild or moderate and their incidence is similar to that found with placebo or lamivudine. Moreover, in treatment-naïve patients, no resistance has been observed after 3 years of therapy. However, in patients with prior resistance to lamivudine, the incidence of resistance is approximately 15% at 3 years. Further studies are required that compare this drug with other currently available therapeutic options, as well as longer term trials to evaluate its safety. It seems that entecavir will occupy a major place in the treatment of patients with chronic hepatitis B virus infection.

Care of HIV patients with chronic hepatitis B: updated recommendations from the HIV-Hepatitis B Virus International Panel

Nearly 10% of the estimated 36 million people having HIV worldwide suffer from chronic hepatitis B virus (HBV) infection. The advent of new antiviral agents against HBV and the recent availability of improved molecular diagnostic tools have revolutioned the management of HIV/HBV coinfected patients. The present study represents an update of the current knowledge about HBV/HIV coinfection and an intent to provide practical advise about how to give the best care to HIV-infected persons with chronic hepatitis B.

Recent data on treatment of chronic hepatitis B with nucleos(t)ide analogues

Forty years ago in 1967, Professor Blumberg discovered the Australian Antigen, later known as the hepatitis B surface antigen, and was awarded the Nobel Prize. This discovery enables the diagnosis of hepatitis B virus (HBV) infection and defines its epidemiology. Viral hepatitis B infection affects global health situation, and chronic hepatitis B (CHB) is particularly serious in the Asia-Pacific region. HBV vaccines created the first breakthrough in HBV prevention. Through universal HBV vaccination program for the newborns, promoted since the mid-1980s, the main route that perpetuates chronic infection from mother to child is curbed. Most children and young adults now have immunity against HBV infection. The next breakthrough comes with therapy for CHB. This prevents progression to cirrhosis and hepatocellular carcinoma. Standard interferon therapy with modest efficacy has been largely replaced by therapy with nuclos(t)ide analogues or pegylated interferons alfa-2a and -2b. Lamivudine was approved by the FDA USA in 1998, followed by adefovir dipivoxil in 2002, entecavir in 2005, and telbivudine in 2006. Clevudine, tenofovir, and many promising candidates are in different stages of development and clinical trial. This paper critically reviews recent data published or presented since the APASL Consensus and Guideline Update of 2005. Clinical efficacy mostly in patients with raised serum alanine aminotransferase will be analyzed.

Current approaches for treating chronic hepatitis B: when to start, what to start with, and when to stop

The natural course of hepatitis B virus (HBV) infection is variable, and chronic hepatitis B (CHB) disease exhibits itself through a spectrum of clinical manifestations. These factors contribute to the challenges faced when managing patients who live with HBV infection. Furthermore, conventional treatment options (e.g., interferon alfa-2a, lamivudine, and adefovir) are moderately effective and can be associated with problems, such as poor tolerability (interferon alfa-2a) and the development of drug resistance (lamivudine). Over the last 5 years, several antiviral agents including entecavir, peginterferon alfa-2a, and telbivudine which are more efficacious and have improved tolerability over previous drugs have become available. The availability of novel antiviral agents and advances in understanding resistance patterns of antiviral agents has resulted in refinement of CHB treatment recommendations and guidelines. More recently, evidence from clinical trials suggests the central importance of virologic suppression as an indicator of treatment outcome and the predictive value of on-treatment HBV DNA levels in response to antiviral therapy. This review highlights the goals of therapy and clinical experience with therapies that are newly licensed or in the late stages of clinical development. Current approaches for treating CHB and new strategies for optimizing response to therapy are also discussed.

Economic implications of entecavir treatment in suppressing viral replication in chronic hepatitis B (CHB) patients in China from a perspective of the Chinese Social Security program

OBJECTIVES

Of estimated 112 million persons infected with chronic hepatitis B (CHB) in China, 15% to 40% will eventually develop liver complications. Most patients do not actively seek antiviral agents for treatment due in part to lack of good understanding of the disease. Entecavir is a new therapeutic option for CHB patients and the purpose of this study was to evaluate the cost-effectiveness of entecavir treatment in China, based on projected clinical benefits from its superior viral suppression efficacy.

METHODS

The analysis was based on the perspective of the Chinese Social Security program. Adjusted relative risks on the association between viral load (VL) and clinical end points (liver cirrhosis/hepatocellular carcinoma) were derived from a publication of a Taiwan CHB prospective cohort with 42,115 person-years of follow-up, and applied to patients enrolled in a randomized phase III trial in China. In this trial, hepatitis B virus (HBV) DNA (by polymerase chain reaction assay) was the key efficacy end point after 48 weeks of treatment with either entecavir or lamivudine monotherapy. Entecavir and lamivudine daily prices were assumed to be Renminbi Yuan (RMB) 40 and 16.71, respectively. Life expectancy tables were based on China vital statistics. Direct medical cost and utility scores for different phases of CHB were estimated from published China specific data, and costs were adjusted to 2006 values using the Chinese Consumer Price Index. Probabilistic sensitivity analyses were conducted to evaluate parameter uncertainty on event distribution and treatment failure rates beyond the trial period.

RESULTS

A total of 519 subjects were enrolled in the study, comprising of 82% males, 87% HBeAg+, and a mean age of 30 years. Based on the efficacy measurement of the percentage of patients achieving HBV DNA <300 copies/ml at week 48, entecavir was superior to lamivudine (78.7% vs. 46.7%, respectively [P < 0.05]). In the base case, compared with lamivudine, 1 year of entecavir therapy gained 0.305 quality-adjusted life year (QALY) at an incremental cost of 5368 RMB, with a 3% annual discount. Compared with lamivudine, using entecavir cost an incremental 17,590 RMB per QALY gained (95% CI 6333-56,407).

CONCLUSIONS

Based on the results of this study, entecavir is likely to be cost-effective in treating hepatitis B patients in China based on the World Health Organization's recommended maximum willingness to pay threshold.

The implications of antiviral drugs with activity against hepatitis B virus and HIV

PURPOSE OF REVIEW

Around 10% of individuals infected with HIV suffer from chronic hepatitis B virus infection. This represents at least 4 million people worldwide. HIV infection modifies the course of hepatitis B virus associated liver disease with faster progression to cirrhosis. The number of anti-hepatitis B virus drugs has increased within the last few years, and some of them also exert activity against HIV-1. The aim of this article is to update the current knowledge on antiviral therapy for chronic hepatitis B in HIV-infected patients.

RECENT FINDINGS

In the absence of successful anti-hepatitis B virus therapy, morbidity and mortality associated with liver disease are increased in hepatitis B virus/HIV coinfected individuals. Data derived from studies using new more potent anti-hepatitis B virus drugs are very promising, and strategies to use these antivirals sequentially and/or in combination are being developed. Hopefully, this success will help bring a halt to liver-related complications and death in the hepatitis B virus/HIV coinfected population.

SUMMARY

Appropriate diagnosis and monitoring of chronic hepatitis B, including the use of noninvasive tools for assessing liver fibrosis, measurement of serum hepatitis B virus-DNA, and drug resistance testing, along with wise use of antivirals may convert hepatitis B virus/HIV coinfection into a manageable disease.

Telbivudine versus lamivudine in Chinese patients with chronic hepatitis B: Results at 1 year of a randomized, double-blind trial

Chronic hepatitis B and its life-threatening sequelae are highly prevalent in China. There is a need for effective new therapies to suppress hepatitis B virus (HBV) replication and ameliorate liver disease. In this study, we compared the efficacy of telbivudine, a nucleoside analogue, with lamivudine in Chinese patients. In this phase III, double-blind, multicenter trial conducted in China, 332 patients with compensated hepatitis B e antigen (HBeAg)-positive or HBeAg-negative chronic hepatitis B were randomly assigned to treatment with 600 mg of telbivudine or 100 mg of lamivudine daily for 104 weeks. The primary efficacy endpoint was reduction in serum HBV DNA levels at week 52 of treatment. Secondary endpoints included clearance of HBV DNA to undetectable levels, HBeAg loss and seroconversion, therapeutic response, and alanine aminotransferase (ALT) normalization. Viral resistance and safety were assessed. At week 52, among 290 HBeAg-positive patients, mean reductions of serum HBV DNA were significantly greater in telbivudine recipients than lamivudine recipients (6.3 log(10) versus 5.5 log(10), P < 0.001), and HBV DNA was polymerase chain reaction-negative in significantly more telbivudine recipients than lamivudine recipients (67% versus 38%, P < 0.001). ALT normalization (87% versus 75%, P = 0.007), therapeutic response (85% versus 62%, P = 0.001), and HBeAg loss (31% versus 20%, P = 0.047) were also significantly more common in the telbivudine group. Treatment effects showed similar patterns in the smaller HBeAg-negative group (n = 42). Viral resistance in telbivudine recipients was approximately half that observed with lamivudine; however, this difference was not statistically significant. Clinical adverse events were similar in the two treatment groups.

CONCLUSION

In Chinese patients with chronic hepatitis B, telbivudine treatment for 52 weeks provided greater antiviral and clinical efficacy than lamivudine, with less resistance.