Drug Disposition Issues in CKD: Implications for Drug Discovery and Regulatory Approval

Comparative pharmacokinetics of six bioactive components of Shen-Wu-Yi-Shen tablets in normal and chronic renal failure rats based on UPLC-TSQ-MS/MS

ETHNOPHARMACOLOGICAL RELEVANCE

Shen-Wu-Yi-Shen tablets (SWYST), a Chinese patent medicine consisting of 12 herbal medicines, was formulated by a famous TCM nephrologist, Zou Yunxiang. It is clinically used to improve the symptoms of nausea, vomiting, poor appetite, dry mouth and throat, and dry stool in patients with chronic renal failure (CRF) accompanied by qi and yin deficiency, dampness, and turbidity. SWYST can reduce urea nitrogen, blood creatinine, and urinary protein loss, and increase the endogenous creatinine clearance rate. However, little is known about its pharmacokinetics.

AIM OF STUDY

To compare the pharmacokinetics of six bioactive components after oral administration of SWYST in normal and adenine-induced CRF rats.

MATERIALS AND METHODS

A method based on ultra-performance liquid chromatography coupled with a triple-stage quadrupole mass spectrometer (UPLC-TSQ-MS/MS) was developed and validated to determine the six bioactive compounds (albiflorin, paeoniflorin, plantagoguanidinic acid, rhein, aloe-emodin, and emodin) in rat plasma. Rat plasma samples were prepared using protein precipitation. Chromatography was performed on an Agilent Eclipse Plus C18 column (3.0 × 50 mm, 1.8 μm) using gradient elution with a mobile phase composed of acetonitrile and water containing 0.1% (v/v) formic acid, while detection was achieved by electrospray ionization MS under the multiple selective reaction monitoring modes. After SWYST administration, rat plasma was collected at different time points, and the pharmacokinetic parameters of six analytes were calculated and analyzed based on the measured plasma concentrations.

RESULTS

The UPLC-TSQ-MS/MS method was fully validated for its satisfactory linearity (r ≥ 0.9913), good precisions (RSD <11.5%), and accuracy (RE: -13.4∼13.1%), as well as acceptable limits in the extraction recoveries, matrix effects, and stability (RSD <15%). In normal rats, the six analytes were rapidly absorbed (Tmax ≤ 2 h), and approximately 80% of their total exposure was eliminated within 10 h. Moreover, in normal rats, the AUC0-t and Cmax of albiflorin, plantagoguanidinic acid, and rhein exhibited linear pharmacokinetics within the dose ranges, while that of paeoniflorin is non-linear. However, in CRF rats, the six analytes exhibited reduced elimination and significantly different AUC or Cmax values. These changes may reflect a decreased renal clearance rate or inhibition of drug-metabolizing enzymes and transporters in the liver and gastrointestinal tract caused by CRF.

CONCLUSIONS

A sensitive UPLC-TSQ-MS/MS method was validated and used to investigate the pharmacokinetics of SWYST in normal and CRF rats. This is the first study to investigate the pharmacokinetics of SWYST, and our findings elucidate the causes of their different pharmacokinetic behaviors in CRF rats. Furthermore, the results provide useful information to guide further research on the pharmacokinetic-pharmacodynamic correlation and clinical application of SWYST.

Quantification of CYP3A and Drug Transporters Activity in Healthy Young, Healthy Elderly and Chronic Kidney Disease Elderly Patients by a Microdose Cocktail Approach

Background: Ageing and chronic kidney disease (CKD) affect pharmacokinetic (PK) parameters. Since mechanisms are related and remain unclear, cytochrome P450 (CYP) 3A and drug transporter activities were investigated in the elderly with or without CKD and compared to healthy adults using a microdose cocktail. Methods: Healthy young participants (n = 20), healthy elderly participants (n = 16) and elderly patients with CKD (n = 17) received, in study period 1, a single dose of microdose cocktail probe containing 30 µg midazolam, 750 µg dabigatran etexilate, 100 µg atorvastatin, 10 µg pitavastatin, and 50 µg rosuvastatin. After a 14-day wash-out period, healthy young participants continued to study period 2 with the microdose cocktail plus rifampicin. PK parameters including area under the plasma concentration-time curve (AUC), maximum plasma drug concentration (C_max), and half-life were estimated before making pairwise comparisons of geometric mean ratios (GMR) between groups. Results: AUC and C_max GMR (95% confidence interval; CI) of midazolam, a CYP3A probe substrate, were increased 2.30 (1.70-3.09) and 2.90 (2.16-3.88) fold in healthy elderly and elderly patients with CKD, respectively, together with a prolonged half-life. AUC and C_max GMR (95%CI) of atorvastatin, another CYP3A substrate, was increased 2.14 (1.52-3.02) fold in healthy elderly and 4.15 (2.98-5.79) fold in elderly patients with CKD, indicating decreased CYP3A activity related to ageing. Associated AUC changes in the probe drug whose activity could be modified by intestinal P-glycoprotein (P-gp) activity, dabigatran etexilate, were observed in patients with CKD. However, whether the activity of pitavastatin and rosuvastatin is modified by organic anion transporting polypeptide 1B (OATP1B) and of breast cancer resistance protein (BCRP), respectively, in elderly participants with or without CKD was inconclusive. Conclusions: CYP3A activity is reduced in ageing. Intestinal P-gp function might be affected by CKD, but further confirmation appears warranted. Clinical Trial Registration:http://www.thaiclinicaltrials.org/ (TCTR 20180312002 registered on March 07, 2018).

Incorporating pharmacokinetic data into personalised prescribing for older people: challenges and opportunities

PURPOSE

We discuss the known age-associated changes in drug metabolism and elimination, the potential use of this information when selecting specific therapeutic strategies in older patients, and the steps required to fill the knowledge gap in this field.

METHODS

We conducted a narrative review that encapsulates the current knowledge regarding the main age-associated changes in drug metabolism and elimination and discusses their possible inclusion in current and future personalised prescribing tools for the older patient population.

RESULTS

Despite some progress in this field, the lack of specific information regarding the impact of frailty, pharmacogenomics, and drug-drug, drug-disease, and organ-organ interactions, particularly in subjects > 80 years, currently prevents the routine incorporation of pharmacokinetic data, barring measures of renal function, into personalised prescribing tools.

CONCLUSIONS

The incorporation of pharmacokinetic data into personalised prescribing, an approach based on the consideration of a number of patient's characteristics when selecting the right drug(s) and dose regimen(s) to maximize effectiveness and limit toxicity, remains a hypothetical construct in geriatric care. Pending the inclusion of frail and complex older patients in pre- and post-marketing studies, a better understanding of the key pharmacokinetic alterations of common medications in "real-life" patients, together with the implementation of effective strategies tackling inappropriate prescribing, is likely to improve clinical outcomes and reduce healthcare utilization in the older population.

Estrogen and estrogen receptors in kidney diseases

Acute kidney injury (AKI) and chronic kidney disease (CKD) are posing great threats to global health within this century. Studies have suggested that estrogen and estrogen receptors (ERs) play important roles in many physiological processes in the kidney. For instance, they are crucial in maintaining mitochondrial homeostasis and modulating endothelin-1 (ET-1) system in the kidney. Estrogen takes part in the kidney repair and regeneration via its receptors. Estrogen also participates in the regulation of phosphorus homeostasis via its receptors in the proximal tubule. The ERα polymorphisms have been associated with the susceptibilities and outcomes of several renal diseases. As a consequence, the altered or dysregulated estrogen/ERs signaling pathways may contribute to a variety of kidney diseases, including various causes-induced AKI, diabetic kidney disease (DKD), lupus nephritis (LN), IgA nephropathy (IgAN), CKD complications, etc. Experimental and clinical studies have shown that targeting estrogen/ERs signaling pathways might have protective effects against certain renal disorders. However, many unsolved problems still exist in knowledge regarding the roles of estrogen and ERs in distinct kidney diseases. Further research is needed to shed light on this area and to enable the discovery of pathway-specific therapies for kidney diseases.

Mitochondrial Damage and Activation of the STING Pathway Lead to Renal Inflammation and Fibrosis

Fibrosis is the final common pathway leading to end-stage renal failure. By analyzing the kidneys of patients and animal models with fibrosis, we observed a significant mitochondrial defect, including the loss of the mitochondrial transcription factor A (TFAM) in kidney tubule cells. Here, we generated mice with tubule-specific deletion of TFAM (Ksp-Cre/Tfamflox/flox). While these mice developed severe mitochondrial loss and energetic deficit by 6 weeks of age, kidney fibrosis, immune cell infiltration, and progressive azotemia causing death were only observed around 12 weeks of age. In renal cells of TFAM KO (knockout) mice, aberrant packaging of the mitochondrial DNA (mtDNA) resulted in its cytosolic translocation, activation of the cytosolic cGAS-stimulator of interferon genes (STING) DNA sensing pathway, and thus cytokine expression and immune cell recruitment. Ablation of STING ameliorated kidney fibrosis in mouse models of chronic kidney disease, demonstrating how TFAM sequesters mtDNA to limit the inflammation leading to fibrosis.

Efficacy and safety of Tripterygium wilfordii Hook F for CKD in Mainland China: A systematic review and meta-analysis

Tripterygium wilfordii Hook F (TwHF) is a promising Chinese traditional medicine used to significantly reduce proteinuria and improve renal function. However, its efficacy and safety in treatment of chronic kidney disease need to be further explored in order to promote its application in clinics. This review compared the efficacy and safety of TwHF with the placebo, conventional Western medicine and other immunosuppressive medicine in a range of kidney disorders. One hundred three randomized controlled trials were included. TwHF therapy decreased 24-hr proteinuria by 0.59 g/day (95% confidence interval [CI; -0.68, -0.50]), serum creatinine level by 1.93 μmol/L (95% CI [-3.69, -0.17]), and blood urea nitrogen level by 0.24 mmol/L (95% CI [-0.41, -0.07]); increased the total effective rate by 27% (95% CI [1.24, 1.30]); and decreased the incidence of adverse reactions by 19% (95% CI [0.68, 0.96]) overall. Meta regression results showed that the duration of therapy and mean age of participants were the major sources of high heterogeneity. Sensitivity analysis demonstrated that our statistic results were relatively stable and credible. The present findings suggested that TwHF possibly has nephroprotective effects by decreasing proteinuria, serum creatinine level, and blood urea nitrogen level and no more adverse reactions compared with control group in most kidney disorders. However, these findings still need to be further confirmed by high-quality trials.

Disposition and clinical implications of protein-bound uremic toxins

In patients with chronic kidney disease (CKD), adequate renal clearance is compromised, resulting in the accumulation of a plethora of uremic solutes. These uremic retention solutes, also named uremic toxins, are a heterogeneous group of organic compounds with intrinsic biological activities, many of which are too large to be filtered and/or are protein bound. The renal excretion of protein-bound toxins depends largely on active tubular secretion, which shifts the binding and allows for active secretion of the free fraction. To facilitate this process, renal proximal tubule cells are equipped with a range of transporters that co-operate in basolateral uptake and luminal excretion. Many of these transporters have been characterized as mediators of drug disposition, but have recently been recognized for their importance in the proximal renal tubular transport of uremic toxins as well. This also indicates that during uremia, drug disposition may be severely affected as a result of drug–uremic toxin interaction. In addition, CKD patients receive various drugs to treat their complications potentially resulting in drug–drug interactions (DDIs), also for drugs that are non-renally excreted. This review discusses the current knowledge on formation, disposition and removal of protein-bound uremic toxins. Furthermore, implications associated with drug treatment in kidney failure, as well as innovative renal replacement therapies targetting the protein-bound uremic toxins are being discussed. It will become clear that the complex problems associated with uremia warrant a transdisciplinary approach that unites research experts in the area of fundamental biomedical research with their colleagues in clinical nephrology.

Wearable sensors: can they benefit patients with chronic kidney disease?

INTRODUCTION

This article ponders upon wearable medical measurement devices in relation to Chronic Kidney Disease (CKD) and its' associated comorbidities - and whether these might benefit CKD-patients. We aimed to map the intersection(s) of nephrology and wearable sensor technology to help technologists understand medical aspects, and clinicians to understand technological possibilities that are available (or soon will become so). Areas covered: A structured literature search on main comorbidities and complications CKD patients suffer from, was used to steer mini-reviews on wearable sensor technologies clustered around 3 themes being: Cardiovascular-related, diabetes-related and physical fitness/frailty. This review excludes wearable dialysis - although also strongly enabled by miniaturization - because that highly important theme deserves separate in-depth reviewing. Expert commentary: Continuous progress in integrated electronics miniaturization enormously lowered price, size, weight and energy consumption of electronic sensors, processing power, memory and wireless connectivity. These combined factors boost opportunities for wearable medical sensors. Such devices can be regarded as enablers for: Remote monitoring, influencing human behaviour (exercise, dietary), enhanced home care, remote consults, patient education and peer networks. However, to make wearable medical devices succeed, the challenge to fit them into health care structures will be dominant over the challenge to realize the bare technologies themselves.