Pharmacokinetics of Roxadustat: A Population Analysis of 2855 Dialysis- and Non-Dialysis-Dependent Patients with Chronic Kidney Disease

A network meta-analysis of therapies for hyperphosphatemia in CKD based on randomized trials

To update the efficacy and safety of different drugs for the treatment of patients with hyperphosphatemia in chronic kidney disease, we conducted a network meta-analysis of 22 therapies for the treatment of uncontrolled hyperphosphatemia in patients with chronic kidney disease (CKD). All randomized controlled trials on hyperphosphatemia published from January 2013 to November 2023 were searched from CNKI, VIP database, Wanfang database, PubMed, Scopus, and Cochrane databases. Meta-analysis was used to evaluate the serum phosphorus, calcium levels, total effective rate and adverse events of patients with chronic kidney disease (CKD). Data collection and quality evaluation were carried out by three evaluators, RevMan (5.5.3) and Stata (1.3.0). A total of 71 RCTs, and 22 treatment strategies were included in this NMA. The results showed that all treatment strategies were effective in improving patients' blood phosphorus levels. Among them, SL + CT, CA + CC, SL and TCM had higher overall efficacy, RT, TCM and SL + CT had lower blood phosphorus levels, SL + CT, SL and NAM had lower blood calcium levels, and OAC, CC, NAM and SL had higher safety. Among them, SL + CT seems to be the most recommended treatment strategy. In addition, multidrug combination strategies usually have a higher efficacy and safety profile.

Optimizing the dosing regimen of roxadustat in kidney transplant recipients with early post-transplant anemia

INTRODUCTION

Roxadustat, an oral inhibitor of hypoxia-inducible factor prolyl hydroxylase domain enzymes, has been approved for the treatment of renal anemia. However, there is a lack of study on its pharmacokinetics in kidney transplant recipients (KTRs) with early posttransplant anemia (PTA). Therefore, the aim of this study is to elucidate the pharmacokinetic characteristics of roxadustat in KTRs with early PTA and optimize the dosing regimen.

METHODS

A population pharmacokinetic (PopPK) analysis was performed based on 72-hour full concentration-time profiles collected from 52 Chinese KTRs. Covariates influencing exposure were assessed using stepwise covariate modelling. Monte Carlo simulations were conducted to recommend the dosing regimen for patients with different levels of covariates.

RESULTS

PopPK analysis showed that the concentration-time data can be fully described by a two-compartment model. Body weight (BW) and direct bilirubin (DBIL) levels significant affected the apparent clearance of roxadustat. Based on the established model and the estimated exposures of roxadustat by Monte Carlo simulations, a recommended dosing regimen for KTRs with early PTA at varying BW and DBIL levels were developed. Roxadustat at 100 mg three times weekly were suitable for the majority of KTRs with a DBIL level around 3 μmol/L and BW between 50 and 75 kg. The required dose may need to be increased with higher BW and lower DBIL levels, while decreased with lower BW and higher DBIL levels.

CONCLUSIONS

It was the first PopPK analysis of roxadustat in KTRs with early PTA, which provide a research basis for optimizing the dosing regimen.

Correlation between blood concentration of roxadustat and clinical efficacy in patients with anemia of chronic kidney disease

Roxadustat has been associated with the efficacy and safety in patients with chronic kidney disease-related anemia. However, the relationship between roxadustat blood concentration and clinical efficacy is lacking. To explore of the correlation between clinical efficacy and blood concentration of roxadustat in patients with renal anemia of chronic kidney diseases, so as to provide reference for rational clinical drug use. A total of 46 patients were selected with a diagnosis of renal anemia who were prescribed roxadustat at the department of nephrology of the First Hospital of Hebei Medical University from December 2019 to March 2020. The roxadustat blood concentration was determined at 12 weeks of treatment, according to the cumulative response rate, patients were divided into the response group and the nonresponse group, and the relationship between roxadustat blood concentration and treatment effect was analyzed. We also explored the correlation between various factors and the blood concentration. The patients in the response group had higher roxadustat blood concentrations than the nonresponse group (P < .05), and there was no correlation between blood concentration and clinical characteristics such as age, gender, and dosage (P > .05). The blood concentration of roxadustat was correlated with clinical efficacy. The higher the blood concentration, the better the clinical efficacy, meaning it might be a predictor of efficacy.

Diffusion tensor imaging of the brain white matter microstructure in patients with chronic kidney disease and its correlation with cognition

Purpose

In individuals with chronic kidney disease (CKD), neurological damage is commonly observed. This neurodegeneration is closely linked to microstructural damage to the brain white matter due to the high incidence of cognitive dysfunction. However, the specific pathogenesis of CKD nephropathy caused by cognitive system developmental disorders remains unclear. This study aimed to examine the correlation between cognitive impairment and diffusion parameters obtained on diffusion tensor imaging (DTI) of abnormal white matter tracts in CKD patients.

Methods

Sixty-four patients with CKD were divided into the non-dialysis-dependent CKD (NDD-CKD) group (N = 26) and dialysis-dependent CKD (DD-CKD) group (N = 38) according to the estimated glomerular filtration rate, whereas 43 healthy control subjects (normal control [NC]) were included and underwent cranial magnetic resonance imaging during the same period. Differences in the abnormal white matter microstructure and correlations between them and cognitive scores were assessed using several parameters between the groups.

Results

There were more extensive peri-lesions and distant white matter microstructural changes in the DD-CKD and NDD-CKD groups than in the NC group. DTI diffusion parameters in abnormal white matter regions were associated with impaired cognitive function in CKD patients. The DD-CKD group had worse cognitive function and more severe microstructural damage in the cerebral white matter than the NDD-CKD group.

Conclusion

CKD patients showed cognitive impairment and changes in the brain white matter microstructure; CKD can lead to extensive white matter tract damage. Additionally, diffusion parameters can be used as a complement to describe structural brain damage in CKD patients.

Roxadustat: Not just for anemia

Roxadustat is a recently approved hypoxia-inducible factor prolyl hydroxylase inhibitor that has demonstrated favorable safety and efficacy in the treatment of renal anemia. Recent studies found it also has potential for the treatment of other hypoxia-related diseases. Although clinical studies have not yet found significant adverse or off-target effects of roxadustat, clinicians must be vigilant about these possible effects. Hypoxia-inducible factor regulates the expression of many genes and physiological processes in response to a decreased level of oxygen, but its role in the pathogenesis of different diseases is complex and controversial. In addition to increasing the expression of hypoxia-inducible factor, roxadustat also has some effects that may be HIF-independent, indicating some potential off-target effects. This article reviews the pharmacological characteristics of roxadustat, its current status in the treatment of renal anemia, and its possible effects on other pathological mechanisms.

Clinical Pharmacokinetics and Pharmacodynamics of Roxadustat

The pharmacokinetics of roxadustat are well characterized, with an apparent volume of distribution after oral administration of 22–57 L, apparent clearance of 1.2–2.65 L/h, and renal clearance of 0.030–0.026 L/h in healthy volunteers; the elimination half-life is 9.6–16 h. Plasma binding is 99% and the fraction eliminated by hemodialysis is 2.34%. As an interpretation of the pharmacodynamics of roxadustat, we proposed a concept with a hypothetical cascade of two subsequent effects, first on erythropoetin (EPO) and second on hemoglobin (delta Hb). The primary effect on EPO is observed within a few hours after roxadustat administration and can be modeled using the sigmoidal Hill equation. The concentration at half-maximum effect can be inferred at 10–36 µg/mL, the Hill coefficient at 3.3, and the effect bisection time at 10–17 h, corresponding to EPO half-life. The subsequent effect on hemoglobin (delta Hb) is observed after several weeks and can be interpreted as an irreversible, dose proportional, unsaturable effect, continuing in agreement with the lifespan of red blood cells of 63–112 days.

Population pharmacokinetics of roxadustat in Japanese dialysis-dependent chronic kidney disease patients with anaemia

Aims

Our objective was to develop a population pharmacokinetic (PK) model to describe roxadustat plasma concentrations in Japanese dialysis‐dependent chronic kidney disease (DD‐CKD) patients with renal anaemia and to identify the covariate factors that affect exposure of roxadustat.

Methods

In total, 367 patients (male, 256; female, 111) contributing 1285 concentration values from 4 clinical studies were analysed using a nonlinear mixed‐effects modelling approach. Candidate covariates included clinical characteristics hypothesized to affect roxadustat clearance and bioavailability, such as demographics, hepatic parameters and concomitant drugs.

Results

The roxadustat PK data in Japanese DD‐CKD patients with renal anaemia were well described by a 2‐compartment disposition model with first‐order absorption and interindividual variability on clearance, central volume of distribution and absorption rate constant. Age was identified as a significant covariate on clearance. PK profiles of haemodialysis and peritoneal dialysis patients were comparable. Eighty‐two percent of patients were administered at least 1 phosphate binder (PB). The effect of PBs on roxadustat concentration was modelled as a decrease in bioavailability. Staggered administration of PBs reduced the effect on roxadustat bioavailability. The clinical impact of all covariates on roxadustat PK was mild and manageable as the roxadustat dose was titrated based on haemoglobin level and administered starting from a low dose.

Conclusion

Roxadustat PK in Japanese DD‐CKD patients were successfully described by a population PK model. The identified key covariates included coadministration of PBs on the roxadustat bioavailability and age on clearance of roxadustat.