Plasma tenofovir trough concentrations are associated with renal dysfunction in Japanese patients with HIV infection: a retrospective cohort study

Population Pharmacokinetic Simulations for Dose Optimization of Tenofovir Disoproxil Fumarate in HIV-Infected Patients with Moderate-to-Severe Renal Impairment

Tenofovir disoproxil fumarate (TDF) requires dosage adjustments from the standard 300 mg once daily to every 48-96 h for moderate-to-severe renal impairment to avoid excessive exposure. However, this extended interval can lead to variable drug exposure and inconvenience. This study aimed to utilize the population pharmacokinetic (PPK) models to optimize TDF dosing regimens for HIV-infected patients with renal impairment. A systematic literature search was conducted across PubMed, Cochrane Library, and Scopus databases to identify relevant PPK studies of TDF in HIV-infected patients. From the included studies, the PPK models and associated parameters were extracted. Monte Carlo simulations (n = 2000) were performed to generate concentration-time profiles and derive PK parameters compared against reference ranges. For moderate renal impairment, the TDF 150 mg once-daily regimen achieved cumulative exposure comparable to the approved 300 mg every-other-day regimen. In severe renal impairment, TDF 75-100 mg administered once daily provided similar cumulative exposure as 300 mg every 72-96 h regimen while maintaining daily exposure comparable to the standard dose in patients with normal renal function. The approved extended dosing intervals of 72-96 h exhibited high drug exposure variability, initially resulting in supratherapeutic levels followed by suboptimal levels preceding the subsequent dose administration. In conclusion, administering smaller once-daily doses of TDF maintains consistent daily drug exposure comparable to the standard dose in patients with normal renal function while reducing variability in drug exposure, potentially mitigating the risk of nephrotoxicity. However, additional clinical studies are required to confirm these findings.

Pharmacokinetics of tenofovir alafenamide, emtricitabine, and dolutegravir in a patient on peritoneal dialysis

INTRODUCTION

Peritoneal dialysis (PD) is an effective renal replacement modality in people with HIV (PWH) with end-stage kidney disease (ESKD), particularly those with residual kidney function. Data on pharmacokinetics (PK) of antiretrovirals in patients on peritoneal dialysis are limited.

METHODS

A single-participant study was performed on a 49-year-old gentleman with ESKD on PD and controlled HIV on once daily dolutegravir (DTG) 50 mg + tenofovir alafenamide (TAF) 25 mg / emtricitabine (FTC) 200 mg. He underwent serial blood plasma, peripheral blood mononuclear cell, and urine PK measurements over 24 h after an observed DTG + FTC/TAF dose.

RESULTS

Plasma trough (Cmin) concentrations of TAF, tenofovir (TFV), FTC, and DTG were 0.05, 164, 1,006, and 718 ng/mL, respectively. Intracellular trough concentrations of TFV-DP and FTC-TP were 1142 and 11,201 fmol/million cells, respectively. Compared to published mean trough concentrations in PWH with normal kidney function, observed TFV and FTC trough concentrations were 15.5- and 20-fold higher, while intracellular trough concentrations of TFV-DP and FTC-TP were 2.2-fold and 5.4-fold higher, respectively. TFV and FTC urine levels were 20 times lower than in people with normal GFR.

CONCLUSIONS

In a single ESKD PWH on PD, daily TAF was associated with plasma TFV and intracellular TFV-DP trough concentrations 15-fold and 2-fold higher than those of people with uncompromised kidney function, potentially contributing to nephrotoxicity. This suggests that TFV accumulates on PD; thus, daily TAF in PD patients may require dose adjustment or regimen change to optimize treatment, minimize toxicity, and preserve residual kidney function.

Severe lactic acidosis during tenofovir disoproxil fumarate and cobicistat combination for HIV patient

Lactic acidosis is a rare but serious side effect in individuals receiving nucleoside reverse transcriptase inhibitors. An underweight woman with HIV was admitted to our hospital because of nausea and diffuse myalgia. Her antiretroviral regimen had been changed to tenofovir disoproxil fumarate (TDF)/emtricitabine and darunavir/cobicistat 3 months prior, after which her renal function had gradually declined. After admission, she was diagnosed with lactic acidosis, and a liver biopsy suggested mitochondrial damage. Her plasma tenofovir levels were elevated at the onset of lactic acidosis. We hypothesise that the patient's low body weight, combined with the addition of cobicistat, induced renal dysfunction and led to elevated plasma tenofovir concentrations, resulting in mitochondrial damage and lactic acidosis. Careful monitoring of renal function and lactic acidosis is required during use of TDF-containing regimens for underweight HIV patients, particularly when combined with cobicistat.

Effect of switching from tenofovir disoproxil fumarate to tenofovir alafenamide on estimated glomerular filtration rate slope in patients with HIV: A retrospective observational study

INTRODUCTION

There is limited data on the effects of switching from tenofovir disoproxil fumarate (TDF) to tenofovir alafenamide (TAF) on estimated glomerular filtration rates (eGFR) slope in patients with human immunodeficiency virus (HIV) infection. This study aimed to compare the eGFR slope when administering TDF and TAF and to investigate the predictors of improvement in eGFR slope after switching from TDF to TAF.

METHODS

We conducted a single-center, retrospective, observational study in Japanese patients with HIV infection who switched the antiretroviral drug from TDF to TAF. eGFR was calculated using serum cystatin C. The eGFR slope was defined as the regression coefficient between eGFR and time. Differences between eGFR slope during TDF and TAF administration were compared using Wilcoxon signed rank test. A stepwise logistic regression model was used to examine the associations between improvement of eGFR slope after switching from TDF to TAF and various parameters.

RESULTS

Overall, 63 patients (656 eGFR) were included in the analysis. The median analyzed durations of TDF and TAF exposures were 1.6 and 1.5 years, respectively. There were no significant differences between eGFR slope during TDF and TAF periods (median: 0.6 vs. 4.0 mL/min/1.73 m²/year, p = 0.165). The eGFR slopes during the TDF period and while switching from TDF to TAF were independent predictors of improvement in eGFR slope after switching from TDF to TAF.

CONCLUSIONS

The results suggest that patients with poor renal function and those with progressive worsening during TDF administration would benefit from switching to TAF.

Para-aminosalicylic acid significantly reduced tenofovir exposure in human subjects: Mismatched findings from in vitro to in vivo translational research

AIMS

Tenofovir and para-aminosalicylic acid (PAS) may be coprescribed to treat patients with concomitant infections of human immunodeficiency virus and Mycobacterium tuberculosis bacteria. Both drugs are known to have remarkable renal uptake transporter-mediated clearance. Owing to the lack of clinical studies on drug-drug interaction between the 2 drugs, we conducted a translational clinical study to investigate the effect of PAS on tenofovir pharmacokinetics (PK).

METHODS

Initially, we studied in vitro renal uptake transporter-mediated drug-drug interactions using stably transfected cells with human organic anion transporters (OAT1 and OAT3). Later, we estimated clinical drug interactions using static and physiologically based PK modelling. Finally, we investigated the effects of PAS-calcium formulation (PAS-Ca) on tenofovir disoproxil fumarate PK in healthy male Korean subjects.

RESULTS

PAS inhibited OAT1- and OAT3-mediated tenofovir uptake in vitro. The physiologically based PK drug-drug interaction model suggested a 1.26-fold increase in tenofovir peak plasma concentration when coadministered with PAS. By contrast, an open-label, randomized, crossover clinical trial evaluating the effects of PAS-Ca on tenofovir PK showed significantly altered geometric mean ratio (90% confidence intervals) of maximum plasma concentration (C_max ) and area under the curve (AUC_0-inf ) by 0.33 (0.28-0.38) and 0.29 (0.26-0.33), respectively.

CONCLUSION

Our study findings suggest that the PAS-Ca formulation significantly reduced systemic exposure to tenofovir through an unexplained mechanism, which was contrary to the initial prediction. Caution should be exercised while predicting in vivo PK profiles from in vitro data, particularly when there are potential confounders such as pharmaceutical interactions.

Efficacy and Safety of Elvitegravir/Cobicistat/Emtricitabine/Tenofovir Alafenamide as Maintenance Treatment in HIV/HBV-Coinfected Patients

BACKGROUND

The efficacy and safety of switching from tenofovir disoproxil fumarate-based antiretroviral therapy to coformulated elvitegravir, cobicistat, emtricitabine, and tenofovir alafenamide (E/C/F/TAF) has not been widely investigated in HIV/hepatitis B virus (HBV)-coinfected Asian population.

METHODS

Between February and October 2018, HIV/HBV-coinfected patients who had achieved HIV viral suppression with tenofovir disoproxil fumarate-containing regimens were switched to E/C/F/TAF. Assessments of plasma HBV and HIV viral load, HBV serology, renal function, lipid profiles, and bone mineral density (BMD) were performed at weeks 24 and 48 after switch.

RESULTS

A total of 274 HIV/HBV-coinfected participants were enrolled, with 12.8% testing HBeAg-positive and 94.2% having plasma HBV DNA <20 IU/mL at baseline. At weeks 24 and 48, 92.7% and 89.8% achieved plasma HBV DNA <20 IU/mL; 4.7% and 5.1% had HBV DNA ≥20 IU/mL; and 2.6% and 5.1% had no data, respectively. At weeks 24 and 48, 95.6% and 94.2% of participants maintained HIV RNA <50 copies/mL, respectively. Compared with baseline, the median urine β2-microglobulin-to-creatinine ratio at week 48 decreased significantly from 165 to 90 μg/g (P < 0.001). The mean BMD of the spine and hip improved at week 48 (+1.77% and +1.33%, respectively). Significantly higher lipid profiles were observed after switch to E/C/F/TAF. Thirteen (4.7%) patients withdrew from the study before week 48, with 7 (2.6%) patients because of adverse effects.

CONCLUSIONS

Switch to E/C/F/TAF maintained HBV and HIV viral suppression and resulted in the improvement of proteinuria and BMD of the spine and hip but increased lipid levels in HIV/HBV-coinfected patients at week 48.

Benefits and Limits of Antiretroviral Drug Monitoring in Routine Practice

BACKGROUND

HIV infection is a chronic disease for which therapeutic adherence and tolerance require particular attention.

OBJECTIVE

This study aimed to assess whether and when therapeutic drug monitoring (TDM) could be associated with a benefit in routine practice.

METHODS

All HIV-infected patients who underwent at least one TDM at the University Hospital of Dijon (France) between 1st January 2009 and 31st December 2012 were retrospectively included. Compliance with the recommendations, the results (antiretroviral concentrations), any subsequent therapeutic modifications, and the virological results at 4-8 months were analysed each time TDM was performed. TDM was defined as "practically relevant" when low or high antiretroviral concentrations led to a change in therapy.

RESULTS

Of the 571 patients who followed-up, 43.4% underwent TDM. TDM complying with recommendations (120 patients) was associated with a higher proportion of antiretroviral concentrations outside the therapeutic range (p=0.03). Antiretroviral treatment was modified after TDM in 22.6% of patients. Protease inhibitors, non-nucleoside reverse transcriptase inhibitors and raltegravir were more significantly modified when the measured concentration was outside the therapeutic range (p=0.008, p=0.05 and p=0.02, respectively). Overall, 11.7% of TDM was considered "practically relevant", though there was no significant correlation between subsequent changes in antiretroviral treatment and undetectable final HIV viral load.

CONCLUSION

TDM may be a useful tool in the management of HIV infection in specific situations, but the overall benefit seems moderate in routine practice. TDM cannot be systematic and/or a decision tool per se, but should be included in a comprehensive approach in certain clinical situations.

Determination of nucleosidic/tidic reverse transcriptase inhibitors in plasma and cerebrospinal fluid by ultra-high-pressure liquid chromatography coupled with tandem mass spectrometry

Nucleoside reverse transcriptase inhibitors (NRTIs) have been the first class of antiretroviral drugs used against HIV infection. Despite NRTI-free regimens have been eagerly sought over the years in an effort for treatment simplification, NRTIs remain in most antiretroviral combination treatment. There has been generally a limited interest for their therapeutic drug monitoring, arguably because NRTIs levels measured in plasma poorly predict the concentration of pharmacologically active metabolites in cells. Plasma concentrations do impact cellular levels, while large differences between NRTIs have been found with regard to their ability to distribute into the cerebrospinal fluid (CSF) compartment. The renewed interest for the measurements of NRTIs concentrations in plasma and CSF was raised by ongoing efforts to understand some instances of toxicity or for determining their actual implication in the development of HIV-associated neurological disorders. In this context, a 5-min multiplex ultra-high-pressure chromatography tandem mass spectrometry (UHPLC-MS/MS) analysis in human plasma and CSF was developed for NRTIs used in clinical practice: abacavir, emtricitabine, lamivudine, tenofovir and zidovudine along with zidovudine glucuronide (Gln-ZDV). The 200-fold dilution of blank human plasma was shown to be a reliable surrogate matrix for quantification of NRTIs and Gln-ZDV in CSF. Both methodologies were fully validated over the clinically relevant concentrations, and satisfactorily fulfilled all parameters for bioanalytical methods validation. This sensitive, rapid, and robust UHPLC-MS/MS assay offers a methodology for increasing our understanding of the ability of NRTIs to cross the blood-brain barrier and their potential implication in neuropsychological disorders observed in HIV-infected patients.

Effect of Cobicistat on Tenofovir Disoproxil Fumarate (TDF): What Is True for TAF May Also Be True for TDF

BACKGROUND

The dose of tenofovir alafenamide is reduced from 25 to 10 mg daily when given with boosting agents. However, such dose reduction has never been adopted for tenofovir disoproxil fumarate (TDF). In this study, we aim to quantify the effect of cobicistat (COBI) both on tenofovir concentrations and TDF durability in real life setting.

METHODS

HIV-positive patients receiving TDF-containing antiretroviral therapies with at least 1 assessment of tenofovir plasma trough concentrations were included in the study. Univariate and multivariate regression analyses were performed considering tenofovir concentration as the dependent variable and clinical characteristics as independent covariates. Subsequently, survival and Cox analyses were performed considering as the primary outcome TDF discontinuation for any reasons.

RESULTS

Patients were given TDF with protease inhibitors/ritonavir (n = 212), non-nucleoside reverse transcriptase inhibitors (n = 176), integrase inhibitors (dolutegravir or raltegravir, n = 46), or with elvitegravir/COBI (ELV/COBI) (n = 76). By multivariate analysis, concomitant antiretroviral therapies resulted significantly associated with tenofovir levels, with the highest drug concentrations measured in patients given ELV/COBI. By survival analysis, we found that patients given TDF with ELV/COBI had the lowest rate of drug durability. Overall, these patients had a 2.3-fold increased risk to experience TDF discontinuation.

CONCLUSIONS

Coadministration with COBI resulted in significantly higher tenofovir concentrations and higher TDF discontinuation compared with other antiretroviral regimens. Accordingly, the possibility that the lack of proper dose adjustment for TDF when given with COBI might have biased the safety comparisons with tenofovir alafenamide during registrative trials cannot be ruled out.