Pharmacokinetics and Tolerability of Tenofovir Disoproxil Fumarate 300 mg Once Daily: An Open-Label, Single- and Multiple-Dose Study in Healthy Chinese Subjects

Do Chinese HIV-infected adult patients with altered renal function need to adjust tenofovir disoproxil fumarate dosage? A population pharmacokinetics analysis

Tenofovir disoproxil fumarate (TDF), a prodrug of tenofovir (TFV), is an effective drug in treating patients infected with human immunodeficiency virus (HIV). Previous population pharmacokinetics (PPK) studies have showed the large variabilities in PK of TFV. Furthermore, limited information was known in Chinese populations. Therefore, the aim of this study was to characterize PPK of TDF in Chinese and identify factors that may affect its PK. TFV concentrations (n = 552) from 30 healthy subjects and 162 HIV-infected Chinese adult patients were pooled for PPK analysis by a nonlinear mixed-effects method. The PK of TFV was adequately described as a two-compartment model with first order absorption and elimination. The typical apparent clearance (CL/F) of TFV in 70-kg adults was 137 L/h, higher than that reported in Caucasians and Blacks (45.8-93 L/h). Estimated glomerular filtration rate was identified to be a significant factor influencing CL/F. Monte Carlo simulation showed that the exposure of standard dosing regimen of TDF 300 mg every 24 h in Chinese people with mild renal impairment (60 to 90 ml/min/1.73 m2) was close to that in individuals with normal renal function (90 mL/min). Dose adjustment is not required for patients with mild renal impairment. Our study might offer new clues for optimal dosing strategies in Chinese patients with HIV-infected.

A multicompartment population PK model to predict tenofovir and emtricitabine mucosal tissue concentrations for HIV prevention

A priori use of mathematical modeling and simulation to predict outcomes from incomplete adherence or reduced frequency dosing strategies may mitigate the risk of clinical trial failure with HIV pre-exposure prophylaxis regimens. We developed a semi-physiologic population pharmacokinetic model for two antiretrovirals and their active intracellular metabolites in three mucosal tissues using pharmacokinetic data from a phase I, dose-ranging study. Healthy female volunteers were given a single oral dose of tenofovir disoproxil fumarate (150, 300, or 600 mg) or emtricitabine (100, 200, or 400 mg). Simultaneous co-modeling of all data was performed on a Linux cluster. A 16 compartment, bolus input, linear kinetic model best described the data, containing 986 observations in 23 individuals across three matrices and four analytes. Combined with a defined efficacious concentration target in mucosal tissues, this model can be used to optimize the dose and dosing frequency through Monte-Carlo simulations.

Distribution Evaluation of Tenofovir in the Breast Milk of Mothers With HBeAg-Positive Chronic HBV Infection After Treatment With Tenofovir Alafenamide and Tenofovir Disoproxil Fumarate by a Sensitive UPLC-MS/MS Method

Tenofovir alafenamide (TAF) is a novel prodrug of tenofovir (TFV) that has been approved for the treatment of chronic hepatitis B virus (HBV) infection. It has greater plasma stability and more favorable renal safety than tenofovir disoproxil fumarate (TDF), the first approved oral prodrug of TFV. However, the distribution of TFV in the breast milk of mothers treated with TAF is still unclear. In this study, sixteen participants with chronic HBV infection were enrolled and received antiretroviral therapy with 25 mg of TAF or 300 mg of TDF daily from 24 to 28 weeks of gestation until the 4th week postpartum. For the first time, the distribution of TFV in the breast milk of mothers with chronic HBV infection treated with TAF and its difference from TDF were evaluated by using a sensitive UPLC-MS/MS method. Chromatographic separation was achieved on a Waters ACQUITY UPLC BEH C18 column (1.7 µm 2.1 × 100 mm). Mass spectrometry analysis was performed in positive electrospray ionization mode and multiple reaction monitoring (MRM) conditions of transitions m/z 288.1→176.2 for TFV. This method was linear from 0.5 to 500 ng/ml. Surprisingly, on the third postpartum day, the median Cmax of TFV in the breast milk was much higher in the mothers treated with TAF (101.2 ng/ml) than TDF (21.6 ng/ml) at a similar Tmax of 4 h. Accordingly, the median AUC0-8 value was 755.6 ng h/mL in the mothers taking TAF, which was at a 5-fold higher level than TDF. The concentration of TFV in the breast milk of mothers in both groups decreased with increasing lactation time. These data indicated that there was a relatively higher exposure of TFV in the breast milk of mothers taking TAF, despite the lower dosage compared to TDF. This study provides support for further evaluating the safety of breastfeeding after the administration of TAF and TDF.

Clinical effects of NTCP-inhibitor myrcludex B

With extensive research on the pathogenesis and treatment of hepatitis B virus (HBV) and hepatitis D virus (HDV) infections, the current treatment of interferon and nucleoside or nucleotide analogues provides reasonable control of viral replication in chronic hepatitis B (CHB). However, drug resistance may occur as a result of long-term treatment, and continuous covalently closed circular DNA (cccDNA) can cause disease relapse after drug withdrawal. Therefore, there is an urgent need for safe and effective antiviral drugs or methods to treat HBV and HDV infections. Myrcludex B is the first entry inhibitor that can inactivate HBV and HDV receptors, compete with HBV for the sodium-taurocholate co-transporting polypeptide, which has been identified as the bona fide receptor for HBV and HDV, block HBV infection in hepatocytes, and participate in HBV transcriptional suppression. Myrcludex B plays an important role in the inhibition of HBV replication and is a potential drug for phase III clinical trials. In this article, we review the progress on the efficacy and clinical application of myrcludex B in recent years.

Effects of Tenofovir on the Single-Dose Pharmacokinetics of Intravenous Morinidazole in Healthy Chinese Subjects

The effects of multiple-dose administration of tenofovir disoproxil fumarate (TDF) on the pharmacokinetics of morinidazole (MOR) were compared in healthy subjects. MOR exposure was similar, with an area under the curve from 0 h to infinity (AUC_0-∞) treatment ratio for MOR+TDF/MOR of 1.01 (90% confidence interval, 0.97 to 1.06). No relevant differences were observed regarding plasma exposure of metabolites. Renal clearances of MOR and its metabolites were not affected by TDF. No unexpected safety or tolerability issues were observed.

A Review of Clinical Pharmacokinetic and Pharmacodynamic Profiles of Select Antiretrovirals: Focus on Differences among Chinese Patients

OBJECTIVE

To identify the pharmacokinetic differences of antiretroviral drugs between HIV-infected Chinese patients and patients of other race/ethnicities.

STUDY DESIGN

Results from prospective, open-label pharmacokinetic studies among Chinese and historical data from other race/ethnicities.

PATIENTS

Pharmacokinetics of six commonly used antiretroviral drugs, including zidovudine, lamivudine, tenofovir disoproxil fumarate, nevirapine, efavirenz and lopinavir/ritonavir, was evaluated in HIV-infected Chinese patients and compared with historical data from other race/ethnicities.

ANALYSIS

Pharmacokinetic analyses were performed at the steady state among HIV-infected Chinese patients. Safety data were collected during the follow-up. The pharmacokinetic parameters including maximal concentrations (Cmax), area-under-curve (AUC) and clearance (Cl/F) from the Chinese patients were compared to the historic data from other race/ethnicities.

RESULTS

Current evidence, though limited, suggested that these antiretroviral agents were generally safe and effective among HIV-infected Chinese patients. However, compared with other racial groups, Chinese patients exhibited higher C_max , AUC and lower Cl/F for most of the agents, and the incidences of adverse reactions, for example, liver toxicity, rash, and bone health, were more frequent.

CONCLUSIONS

These pharmacokinetic differences suggest that lower dosages for commonly prescribed antiretroviral drugs in China might be appropriate to reduce drug-related adverse reactions, while maintain the antiviral efficacy.

A randomized, double-blind, double-dummy, controlled, multicenter study of Qingzhong (tenofovir disoproxil fumarate) versus Viread for the treatment of chronic hepatitis B: First-stage results at week 48

BACKGROUND

Tenofovir disoproxil fumarate (TDF) has been widely recommended as a first-line antiviral agent to treat chronic hepatitis B (CHB). Qingzhong and Viread, formulations of TDF commercialized by Jiangsu Chia-tai Tianqing Pharmaceutical Co Ltd and GlaxoSmithKline, respectively, have both been approved by the State Food and Drug Administration, China. This study analyzed the efficacy and safety of these 2 TDF agents in Chinese patients with CHB.

METHODS

In this multicenter, randomized, double-blind, double-dummy, noninferiority phase 3 clinical trial (ClinicalTrials.gov identifier: NCT02287857), 330 Chinese patients with CHB [hepatitis B envelope antigen-positive (HBeAg) (+): 232] were randomly assigned to receive Qingzhong (group A: 161 patients) or Viread (group B: 169 patients) 300 mg once daily for 48 weeks. Subsequently, all patients were administered Qingzhong 300 mg once daily from week 49 to week 240. The primary end point was the degree of decline of plasma hepatitis B virus (HBV) DNA levels at week 48 and the secondary endpoints were viral suppression, normalization of alanine aminotransferase (ALT) levels, hepatitis B surface antigen (HBsAg)/HBeAg loss or seroconversion, and virological breakthrough.

RESULTS

Among patients with CHB who were HBeAg (+), the mean HBV DNA titer decreased similarly between the groups at week 48. The percentages of patients who achieved undetectable HBV DNA were similar between the groups (85.11% and 82.35% in groups A and B, respectively) and similar losses of HBeAg and HBeAg seroconversion rates were achieved. Moreover, for patients with CHB who were HBeAg (-), reductions in HBV DNA were similar. Among all patients with CHB, the rates of normalization of ALT and the loss of HBsAg were similar. The overall incidence of adverse events was comparable between the groups.

CONCLUSION

In conclusion, the 48-week administration of Qingzhong showed noninferior efficacy and safety profiles compared to Viread in Chinese patients with CHB.

Steady-state pharmacokinetics of tenofovir disoproxil fumarate in human immunodeficiency virus-infected Chinese patients

BACKGROUND

The pharmacokinetic (PK) profile of tenofovir disoproxil fumarate in Chinese adults infected with HIV is unknown.

METHODS

A pilot, prospective, open-label study was performed to investigate the steady-state PK profile of tenofovir disoproxil fumarate in 15 Chinese HIV-infected patients among whom eight patients were treated with 300 mg tenofovir disoproxil fumarate, 300 mg lamivudine and 400/100 mg lopinavir/ritonavir, and seven with 300 mg tenofovir disoproxil fumarate, 300 mg lamivudine and 400 mg nevirapine. The plasma concentrations of tenofovir over the 24-h dosing interval were determined by HPLC. The PK parameters were calculated using the non-compartmental model in WinNonlin software.

RESULTS

The PK parameters of tenofovir in the 15 patients were determined as follows (mean ± SD): AUC_{(0-24 h)}, 4074.7 ± 1551.9 ng•h/mL; C_max,ss, 447.1 ± 217.4 ng/mL; C_trough,ss, 98.7 ± 36.7 ng/mL; t_max,ss, 1.3 ± 0.4 h; plasma t_1/2, 21.8 ± 7.6 h; and CL_ss/F, 45.8 ± 13.0 L/h.

CONCLUSION

Tenofovir demonstrated slower elimination rate and increased plasma concentration in Chinese patients compared to previously published data from Caucasian or African subjects, which may be associated with the higher incidences of renal and bone resorption dysfunction observed in our patient population. Clinicians should be cautious of the differing PK characteristics of tenofovir among people of different races.

Population Pharmacokinetics of Tenofovir in HIV-1-Uninfected Members of Serodiscordant Couples and Effect of Dose Reporting Methods

Antiretroviral preexposure prophylaxis (PrEP) with once-daily dosing of tenofovir and tenofovir-emtricitabine was shown to be effective for preventing HIV-1 infection in individuals who had HIV-1-seropositive partners (the Partners PrEP Study). We developed a population pharmacokinetic model for tenofovir and investigated the impacts of different dose reporting methods. Dosing information was collected as patient-reported dosing information (PRDI) from 404 subjects (corresponding to 1,280 drug concentration records) from the main trial and electronic monitoring-based adherence data collected from 211 subjects (corresponding to 327 drug concentration records) in an ancillary adherence study. Model development was conducted with NONMEM (7.2), using PRDI with a steady-state assumption or using PRDI replaced with electronic monitoring records where available. A two-compartment model with first-order absorption was the best model in both modeling approaches, with the need for an absorption lag time when electronic monitoring-based dosing records were included in the analysis. Age, body weight, and creatinine clearance were significant covariates on clearance, but only creatinine clearance was retained in the final models per stepwise selection. Sex was not a significant covariate on clearance. Tenofovir population pharmacokinetic parameter estimates and the precisions of the parameters from the two final models were comparable with the point estimates of the parameters, differing from 0% to 35%, and bootstrap confidence intervals widely overlapped. These findings indicate that PRDI was sufficient for population pharmacokinetic model development in this study, with a high level of adherence per multiple measures.

Increased bone resorption during tenofovir plus lopinavir/ritonavir therapy in Chinese individuals with HIV

We sought to evaluate the effects of antiretroviral therapy on skeletal metabolism in Chinese individuals with human immunodeficiency virus. Patients switched to tenofovir/lamivudine + lopinavir/ritonavir after treatment failure had an increase in bone resorption marker levels by nearly 60%, which is greater than the magnitude previously described in non-Chinese populations.

INTRODUCTION

Few studies have evaluated the effects of antiretroviral therapy on skeletal metabolism in Asian populations infected with human immunodeficiency virus (HIV).

METHODS

We performed a secondary analysis of bone turnover markers (BTM) at baseline and 2 years in stored plasma samples collected from 2/2009 to 1/2013 as part of a multi-center trial. Two groups were compared: (1) treatment-naïve patients initiated on zidovudine (AZT)/lamivudine (3TC) plus nevirapine (NVP) and (2) patients who failed first-line therapy and were switched to tenofovir (TDF)/3TC plus lopinavir/ritonavir (LPVr). Tests included the bone resorption marker, C-terminal cross-linking telopeptide of type-1 collagen (CTX), and the bone formation marker procollagen type 1 N-terminal propeptide (P1NP).

RESULTS

In the TDF/3TC + LPVr group, samples were available from 59 patients at baseline and 56 patients at 2 years. Of these, 36 patients had samples available from both time points. In the AZT/3TC + NVP group, plasma samples were analyzed from 82 participants at baseline and of those, 61 had samples at 2 years. Median change over 2 years was greater in the TDF/3TC + LPVr group for both CTX (+0.24 ng/mL, interquartile ranges (IQR) 0.10-0.43 vs. +0.09 ng/mL, IQR -0.03 to 0.18, p = 0.001) and P1NP (+25.5 ng/mL, IQR 2.4-51.3 vs. +7.11 ng/mL, IQR -4.3 to 21.6, p = 0.012). Differences remained after adjusting for potential confounders in the multivariable analysis.

CONCLUSIONS

Switching to TDF/3TC + LPVr after treatment failure resulted in greater increases in BTMs than initiation with AZT/3TC + NVP in Chinese patients with HIV. Following this change, bone resorption marker levels increased by nearly 60 %, which is greater than the 25-35% increase from baseline described previously in non-Chinese populations. Further studies are warranted to elucidate these findings.