Pharmacokinetics and pharmacodynamics profiles of enteric‐coated mycophenolate sodium in female patients with difficult‐to‐treat lupus nephritis

Relapsed or resistant lupus nephritis (LN) is considered a difficult‐to‐treat type of LN, and enteric‐coated mycophenolate sodium (EC‐MPS) has been used in this condition. Therapeutic drug monitoring using the area under the plasma mycophenolic acid concentration from 0 to 12 h postdose (MPA‐AUC_0–12h) ≥45 μg.h/ml is a useful approach to achieve the highest efficiency. This study assessed EC‐MPS’s pharmacokinetic (PK) and pharmacodynamic (PD) profiles and investigated an optimal level of the single time point of plasma MPA concentration. Nineteen biopsy‐proven patients with class III/IV LN received 1440 mg/day of EC‐MPS for 24 weeks. PK (maximum plasma MPA concentration [C _max], time to C _max, and MPA‐AUC_0–12h) and PD (activity of inosine‐5′‐monophosphate dehydrogenase [IMPDH]) parameters were measured at weeks 2, 8, 16, and 24. We found that IMPDH activity decreased from baseline by 31–42% within 2–4 h after dosing, coinciding with the increased plasma MPA concentration. MPA‐AUC_0–12h ≥45 μg.h/ml was best predicted by a single time point MPA concentration at C0.5, C2, C3, C4, and C8 (r ² = 0.516, 0.514, 0.540, 0.611, and 0.719, respectively), independent of dose, albumin, urine protein/creatinine ratio, and urinalysis. The MPA‐C0.5 cutoff of 2.03 g/ml yielded the highest overall sensitivity of 85% and specificity of 88.2% in predicting MPA‐AUC_0–12h ≥45 μg.h/ml. A single timepoint of plasma MPA‐C0.5 ≥2.03 μg/ml may help guide EC‐MPS adjustment to achieve adequate drug exposure. Further study of EC‐MPS used to validate this cutoff is warranted.

Study Highlights WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC? Therapeutic drug monitoring (TDM) is crucial in lupus nephritis (LN) treated with mycophenolic acid (MPA), especially mycophenolate mofetil. The area under the plasma concentration‐time curve of MPA from time 0 to 12 h (MPA‐AUC_0–12h) ≥ 45 μg.h/ml or a single plasma MPA concentration (C0 or C1) are used as tools to enhance the highest treatment efficacy. In addition, enteric‐coated mycophenolate sodium (EC‐MPS) was also used to treat relapsed or resistant LN. However, little is known regarding the TDM of EC‐MPS. WHAT QUESTION DID THIS STUDY ADDRESS? This study assessed EC‐MPS’s pharmacokinetics (PKs) and pharmacodynamics (PDs) in adult patients with relapsed or resistant LN and investigated a surrogate single timepoint of plasma MPA concentration with optimum plasma level cutoff as an alternative for MPA‐AUC. WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE? This study provided EC‐MPS’s PK and PD profiles and suggested a surrogate single timepoint of plasma MPA concentration with optimum plasma level cutoff as potential alternatives for MPA‐AUC_0–12 ≥45 μg.h/ml to be applied in TDM. HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE? This study supports the role of TDM in relapsed or resistant LN treated with EC‐MPS. In addition, a single timepoint of plasma MPA concentration at C0.5 with the proposed cutoff at ≥2.03 μg/ml is a TDM tool that can be easily applied in clinical practice. However, a more significant number of study patients is required.     

Super high‐flux hemodialysis provides comparable effectiveness with high‐volume postdilution online hemodiafiltration in removing protein‐bound and middle‐molecule uremic toxins: A prospective cross‐over randomized controlled trial

Although high‐volume postdilution online hemodiafiltration (ol‐HDF) is superior to high‐flux HD in removing all kinds of uremic toxins and improving survival, this treatment is not available in most HD centers. The present study was conducted to compare the effectiveness in removals of protein‐bound (indoxyl sulfate [IS]), middle‐molecule [beta‐2 microglobulin (B2M) and alpha‐1 microglobulin (A1MG)], and small‐molecule uremic toxins between super high‐flux HD (SHF‐HD), HD with a novel SHF dialyzer and high‐volume postdilution ol‐HDF in a noninferiority fashion. Fifteen prevalent HD patients were randomly allocated into two sequences of 12‐week treatment periods of SHF‐HD treatment and later high‐volume postdilution ol‐HDF period or vice versa. Each treatment period was divided by a wash‐out phase of 4‐week high‐flux HD. Twelve of 15 patients could complete the study. When compared with high‐volume postdilution ol‐HDF (convective volume of 24.4 ± 3.52 L), SHF‐HD provided comparable reduction ratio values of IS, B2M, and A1MG with mean difference of 5.87 (95% confidence interval [CI] ‐1.63, 13.37), 1.98 (95% CI,‐0.21, 4.18), and 22.96 (95% CI, ‐1.91, 47.83), respectively. The spKt/Vurea was not different. The predialysis levels of all uremic toxins at baseline and after 12‐week treatment did not differ between both groups. Although albumin loss in dialysate in SHF‐HD was greater than high‐volume postdilution ol‐HDF, the serum albumin levels after 12‐week SHF‐HD treatment were significantly higher than baseline. In conclusion, SHF‐HD provides noninferior effectiveness to high‐volume postdilution ol‐HDF in removing various uremic toxins with significantly increased serum albumin levels despite higher albumin loss. SHF‐HD might be an effectively alternative treatment when high‐volume postdilution ol‐HDF is not available.     

Protein-Bound Uremic Toxins Lowering Effect of Sevelamer in Pre-Dialysis Chronic Kidney Disease Patients with Hyperphosphatemia: A Randomized Controlled Trial

P-cresyl sulfate and indoxyl sulfate are strongly associated with cardiovascular events and all-cause mortality in chronic kidney disease (CKD). This randomized controlled trial was conducted to compare the effects between sevelamer and calcium carbonate on protein-bound uremic toxins in pre-dialysis CKD patients with hyperphosphatemia. Forty pre-dialysis CKD patients with persistent hyperphosphatemia were randomly assigned to receive either 2400 mg of sevelamer daily or 1500 mg of calcium carbonate daily for 24 weeks. A significant decrease of total serum p-cresyl sulfate was observed in sevelamer therapy compared to calcium carbonate therapy (mean difference between two groups −5.61 mg/L; 95% CI −11.01 to −0.27 mg/L; p = 0.04). There was no significant difference in serum indoxyl sulfate levels (p = 0.36). Sevelamer had effects in terms of lowering fibroblast growth factor 23 (p = 0.01) and low-density lipoprotein cholesterol levels (p = 0.04). Sevelamer showed benefits in terms of retarding CKD progression. Changes in vascular stiffness were not found in this study.     

Renal dysfunction does not affect the peripheral-to-central arterial pressure transfer function

Arterial generalized transfer functions (GTFs) are increasingly used to estimate central pressure from peripheral measurements. Analysis of derived central waveforms may be valuable in the assessment of patients with chronic kidney disease. The aim of this study was to assess whether the GTF is affected by renal disease. Ninety-four subjects with varying degrees of renal function (Kidney Disease Outcomes Quality Initiative stages 1 to 5; 14 controls) had simultaneous measurements of carotid and radial waveforms made by applanation tonometry. GTFs were calculated by Fourier analysis for each subject group. Derived carotid waveforms were obtained by applying an independently generated GTF to the radial waveform. Glomerular filtration rate inversely correlated with central systolic (R = -0.42; P < 0.001), mean (R = -0.34; P < 0.01) and diastolic (R = --0.27, P < 0.01) blood pressures, as well as central augmentation index (R = -0.30; P< 0.01) and carotid-femoral pulse wave velocity (R = -0.33; P < 0.001). Derived waveforms were not significantly different from measured waveforms in terms of systolic blood pressure, augmentation index, maximum slope, or the delay between the incident and reflected waves, although the derived waveforms slightly underestimated the systolic ejection period (-4.4 ± 0.9 ms; P < 0.001). Overall root-mean-square error was 2.4 ± 0.1 mm Hg. No significant relationship existed between the degree of bias of any derived waveform measure and glomerular filtration rate or chronic kidney disease stage (P > 0.16). No significant differences between chronic kidney disease stages were observed in transfer function gain or phase (P > 0.05). We conclude that the peripheral-to-central GTF is not affected by degree of renal dysfunction and can be used with equivalence in patients with varying degrees of chronic kidney disease.     

Risk factors for metabolic syndrome independently predict arterial stiffness and endothelial dysfunction in patients with chronic kidney disease and minimal comorbidity

OBJECTIVE

Metabolic syndrome (MS) is common in patients with chronic kidney disease (CKD), but its contribution to arterial stiffness and endothelial dysfunction in CKD is not well defined. We hypothesized that risk factors for MS would independently predict arterial stiffness and endothelial dysfunction in CKD patients.

RESEARCH DESIGN AND METHODS

Risk factors for MS, carotid-femoral pulse wave velocity (CF-PWV) and flow-mediated dilation (FMD) as measures of arterial stiffness and endothelial dysfunction, respectively, were assessed in 113 minimally comorbid CKD patients and in 23 matched control subjects.

RESULTS

CF-PWV correlated with systolic blood pressure (SBP), waist circumference, and plasma glucose (r² = 0.25, 0.09, and 0.09; P < 0.01 for all). FMD correlated with SBP (r² = 0.09; P < 0.01) and waist circumference (r² = 0.03; P < 0.05). CF-PWV increased progressively (r² = 0.07; P < 0.01) with increasing number of risk factors for MS. In multiple linear regression, SBP and waist circumference were independent determinants of CF-PWV, whereas only SBP predicted FMD.

CONCLUSIONS

The number of MS risk factors is an important determinant of arterial stiffness in CKD patients irrespective of the degree of renal impairment. Although BP remains the major determinant of arterial stiffness and endothelial dysfunction, waist circumference independently predicts arterial stiffness. MS risk factors, particularly abdominal girth, are potential targets for future interventional studies in patients with CKD.Chronic kidney disease (CKD) is common and associated with an increased risk of cardiovascular disease (CVD) (1). Conventional (Framingham) CVD risk factors, including high blood pressure (BP), hypercholesterolemia, and diabetes, all of which are common in CKD patients, only partly explain the high cardiovascular risk (2). CKD is now regarded as an independent risk factor for CVD (1,3), and we have recently shown that renal dysfunction also contributes to arterial stiffness and endothelial dysfunction in a group of minimally comorbid CKD patients (4).Increased arterial stiffness, as measured by pulse wave velocity (PWV), is a commonly recognized feature of CKD (4), a marker of cardiovascular risk (5,6), and an independent predictor of mortality and survival in dialysis patients (6). The vascular endothelium is an important regulator of arterial stiffness (7), and endothelial dysfunction is also a common feature of CKD (8) and a predictor of CVD (9).Metabolic syndrome (MS) is a clustering of metabolic abnormalities and risk factors for CVD and includes abdominal obesity, hyperglycemia, hypertension, hypertriglyceridemia, and reduced HDL cholesterol (10). As MS is associated with increased risks of diabetes and CVD (11,12), its treatment and prevention have become one of the major public health challenges worldwide. The risk factors for MS, either together or individually, are also associated with arterial stiffness and endothelial dysfunction both in health (13,14) and disease (15,16).MS is widely prevalent in CKD (17) and is itself a risk factor for CKD (18). Although a recent study has suggested that MS and its risk factors contribute to arterial stiffness and endothelial dysfunction in dialysis patients (19), there are no data relating to predialysis CKD. This is clearly important because targeting MS risk factors in early CKD may retard CKD progression, delaying the onset of dialysis and its associated morbidity, as well as reducing the overall risk of CVD.In this current study, we investigated the relationships of MS and its individual components to arterial stiffness and endothelial dysfunction in CKD patients across a wide range of renal function from early CKD to predialysis. Importantly, we planned to recruit patients without diabetes or cardiovascular comorbidity. We hypothesized that the presence of MS, or its components, would be associated with increased arterial stiffness and endothelial dysfunction and that these relationships would be independent of renal function and other well-established risk factors for CVD.     

Are rare diseases still orphans or happily adopted? The challenges of developing and using orphan medicinal products

Orphan medicinal products (OMPs) are targeted at the diagnosis, prevention or treatment of rare diseases and have a special status in European law. This status brings incentives for pharmaceutical companies to invest in OMP development. The goal of the legislation is to encourage the development of more treatments for life-threatening rare disorders, but increased availability of OMPs raises important issues surrounding the public funding of very expensive treatments by national health services. In this article we review OMPs and the incentives for their development and discuss the challenges presented by funding these treatments.     

Antioxidant capacity, total phenolics and sugar content of selected Thai health beverages

This study was to determine antioxidant capacity, total phenolics and sugar content of 12 pasteurized and sterilized Thai health beverages, products of The Royal Chitralada Projects. The antioxidant capacities were analyzed using 2,2-diphenyl-l-picrylhydrazyl radical scavenging and the photochemiluminescence (PCL) assay. Folin-Ciocalteu assay and Nelson's reducing sugar test were used to determine total phenolic compounds and sugar contents, respectively. Sacred lotus root drink showed the significantly highest antioxidant capacity in both equivalents to trolox and equivalents to ascorbic acid but not in the PCL test. In contrast, chrysanthemum drink and roselle drink showed the significantly highest values of both the total antioxidant capacity of water and lipid-soluble substances in the PCL assay. Bael fruit drink had the significantly highest total phenolic compounds. There were significant correlations between the total phenolic compounds and the antioxidant capacity values of both assays (r = 0.4-0.5).