Lipoteichoic Acid as a Potential Noninvasive Biomarker of Biofilm in Dialysis Access

Tunneled central venous catheters (TCVCs) are colonized by Gram-positive organisms and form biofilm. Lipoteichoic acid (LTA) is a Gram-positive cell wall component that can be measured in serum. The purpose of this pilot study was to characterize LTA concentrations in hemodialysis (HD) patients with TCVCs compared to other access types and to evaluate biofilm morphology and microbiology in TCVCs removed by clinical decision. The study enrolled patients with TCVCs (18), grafts (19), and fistulas (18). Blood samples were collected before HD, at 30 minutes, 2 hours, and end of HD. Catheters removed by clinical decision were evaluated by scanning electron microscopy (SEM) for biofilm morphology, and portions of the catheter were cultured. LTA was detectable in all samples and concentrations increased significantly in all access types during HD (p < 0.05 for all comparisons). Patients with TCVCs that had a >30% increase in LTA concentration from baseline also had the greatest rate of increase (slope) compared to grafts and fistulas (p = 0.03 and p = 0.04, respectively). Catheters removed by clinical decision (n = 7) and examined by SEM had deposition of fibrin. Cultures revealed polymicrobial colonization. TCVCs had the highest rate of increase of LTA during HD. Further studies to determine the source of LTA in patients with AVG and AVF are warranted.

Approaches to Medication Management in Patients with Kidney Failure Opting for Conservative Management

After consideration of risks and benefits, some patients with kidney failure choose conservative management. Conservative management of kidney failure (CM-KF) does not include dialysis or transplant and utilizes primarily pharmacologic strategies for symptom management, which can be challenging due to the number and complexity of symptoms. Additionally, there are safety concerns regarding altered pharmacokinetics and the adverse effects induced by some of the therapies that may be selected to treat symptoms. This review describes common kidney failure symptoms and provides recommendations for pharmacologic management in CM-KF. Selection of medication should be individualized to the patient and comorbidities, drug interactions, cost, and adverse effects should be carefully considered. Additional studies specifically focused on CM-KF are needed.

Hypoxia-inducible factor prolyl hydroxylase inhibitors: a paradigm shift for treatment of anemia in chronic kidney disease?

INTRODUCTION

The hypoxia-inducible factor prolyl hydroxylase (HIF-PH) pathway is responsible for regulating the biosynthesis of erythropoietin (EPO) and maintaining iron homeostasis. Investigational drugs that target the HIF-PH pathway are promising alternatives for treating anemia in Chronic Kidney Disease (CKD).

AREAS COVERED

This review summarizes recent advances focused on the clinical development of HIF-PH inhibitors (HIF-PHIs) as potentially novel therapies in the treatment of anemia in CKD based on publications available on PubMed and restricted Google searches. We provide a comparison between HIF-PHIs regarding their pharmacokinetics, dosing regimens and safety concerns, structure-activity relationships, and alterations in key laboratory parameters observed in animal models and clinical trials.

EXPERT OPINION

HIF-PHIs may be advantageous in some aspects compared to the conventional erythropoiesis-stimulating agents (ESAs). While ESAs could increase the risk of cardiovascular events due to rapid rises in ESA blood levels, HIF-PHIs have been reported to maintain EPO concentrations at levels that are closer to the normal physiological ranges. Although HIF-PHIs have been demonstrated to be relatively safe and effective in clinical trials, long-term safety data are needed in order to establish whether these therapeutic agents will lead to a major paradigm change in the treatment of anemia of CKD.

Impact of hemodialysis on the concentrations of sodium and potassium during infusion of sodium thiosulfate using an In Vitro hemodialysis model

INTRODUCTION

The purpose of this study was to evaluate the impact of hemodialysis on the concentrations of sodium and potassium in the blood when a 25 g dose of sodium thiosulfate injection is infused over 60 minutes in combination with hemodialysis.

METHODS

Sodium thiosulfate (25 g) was prepared by diluting 100 mL of 250 mg/mL Sodium Thiosulfate Injection with 800 mL of 5% dextrose. This was added to the circulating blood surrogate solution at a rate of 15 mL/minute using an infusion pump of an in vitro model of dialysis machine. Serial samples were collected before the administration of the sodium thiosulfate solution, after 15 minutes, 30 minutes, and 60 minutes of infusion from pre-and post-dialyzer ports in both the dialysate circuit and the extracorporeal circuit.

FINDINGS

The concentration of sodium thiosulfate in pre-dialyzer and post-dialyzer samples of the circulating blood surrogate solution peaked at 30 minutes and 15 minutes, respectively and then remained relatively unchanged during the remainder of the infusion. Mean sodium concentrations (mEq/L) in the circulating blood surrogate solution collected after exposure to a dialyzer were 103.2 ± 12.2, 114.2 ± 18.8, 117.2 ± 7.5, 93.5 ± 5.9 at 0, 15, 30, and 60 minutes, respectively (p = 0.248). Mean potassium concentrations (mEq/L) in the circulating blood surrogate solution collected after exposure to a dialyzer were 1.4 ± 0.3, 1.6 ± 0.3, 1.5 ± 0.1, 1.2 ± 0.1 at 0, 15, 30, and 60 minutes, respectively (p = 0.365). Sodium and potassium concentrations in dialysate increased marginally after exposure to the dialyzer.

DISCUSSION

Our study demonstrates that neither potassium nor sodium accumulated in circulating blood surrogate solution when a dose of sodium thiosulfate was infused in conjunction with hemodialysis.

Assessment of literacy and numeracy skills related to non-steroidal anti-inflammatory drug labels

Background:

Non-steroidal anti-inflammatory drugs are widely used and have a potential for over-the-counter misuse. Limited health literacy is associated with poor health outcomes. Identification of new strategies to assess literacy and numeracy could be useful in targeting effective education initiatives.

Objective:

To characterize numeracy and literacy skills related to non-steroidal anti-inflammatory drug labels in primary care patients.

Methods:

Patients were recruited and consented over an 8-month period after their regular primary care visit. Demographic information was collected and two instruments were administered to assess literacy and numeracy skills: (1) a medication label literacy instrument focused on non-steroidal anti-inflammatory drugs (MedLit-NSAID) and (2) a general healthy literacy-screening tool, the Newest Vital Sign. Two questions on the MedLit-NSAID instrument evaluated understanding of the Food and Drug Administration medication guide for non-steroidal anti-inflammatory drugs and the Food and Drug Administration approved over-the-counter label.

Results:

A total of 145 patients were enrolled. Mean MedLit-NSAID and Newest Vital Sign scores were 6.8 (scale range 0–8) and 4.2 (scale range 0–6), respectively. Higher education level was associated with higher scores for both tools (p ⩽ 0.05). Total MedLit-NSAID scores on average were higher in females compared with males (6.5 vs 6, p = 0.05). Patients with decreased kidney function (n = 18) had significantly lower MedLit-NSAID scores (p ⩽ 0.05). Test–retest scores were not significantly different for MedLit-NSAID (p = 0.32). The correlation between the tools was 0.54 and internal consistency MedLit-NSAID was 0.61.

Conclusion:

A medication information focused instrument provided specific information to assess health literacy related to non-steroidal anti-inflammatory drug labels. This information could be utilized to develop patient education initiatives for medication label comprehension.

Patient-selected media and knowledge of risk to kidneys of nonsteroidal anti-inflammatory drugs

OBJECTIVES

Nonsteroidal anti-inflammatory drugs (NSAIDs) can cause community-acquired acute kidney injury, especially in high-risk populations. Both the U.S. Food and Drug Administration (FDA) medication guide and over-the-counter labeling vaguely describe kidney risks of NSAIDs and do not provide information for patients to evaluate their risk for kidney problems. The purpose of this study was to use a mobile application to evaluate the impact of patient choice of media delivering NSAID avoidance education on patient knowledge about kidney risks associated with NSAIDs.

DESIGN

Prospective cohort study. The mobile application was used to deliver either a redesigned FDA medication guide or a video focused on NSAID risks (selected by the patient), followed by patient knowledge questions (PKQs) and a kidney risk assessment.

SETTING AND PARTICIPANTS

One hundred fifty adult primary care patients in southeast Michigan.

MAIN OUTCOME MEASURES

The primary outcome was the score on 5 NSAID PKQs between the media selected. Secondary outcomes included characterization of media choice among different demographic and NSAID kidney risk groups. The relationship between kidney risk assessment and self-reported NSAID avoidance behavior also was evaluated.

RESULTS

The majority of participants (72.7%) chose to review print material. Those that chose print had significantly higher PKQ scores (5 total points) compared with participants who selected the video: mean scores 4.2 ± 0.9 with print and 3.8 ± 1.0 with video (P = 0.034). Older patients (>65 years) had significantly lower PKQ scores compared with other age groups. Forty-four percent of individuals (n = 66) reported current NSAID use, and 65% stated that they would avoid NSAIDs after the selected education material.

CONCLUSION

Scores for questions related to NSAID kidney risk knowledge were higher among participants who chose print compared with video education material. Education regarding NSAID kidney risks encouraged patients to limit their use. Targeted education may be beneficial in high-risk (e.g., older) patients and should be further studied.

Iron Oxide Nanoparticle Formulations for Supplementation

Intravenous (IV) iron is widely used to provide supplementation when oral iron is ineffective or not tolerated. All commercially available intravenous iron formulations are comprised of iron oxyhydroxide cores coated with carbohydrates of varying structure and branch characteristics. The diameter of the iron-carbohydrate complexes ranges from 5-100 nm and meets criteria for nanoparticles. Clinical use of IV iron formulations entered clinical practice beginning of the late 1950s, which preceded the nanomedicine exploration frontier. Thus, these agents were approved without full exploration of labile iron release profiles or comprehensive biodistribution studies. The hypothesis for the pathogenesis of acute oxidative stress induced by intravenous iron formulations is the release of iron from the iron-carbohydrate structure, resulting in transient concentrations of labile plasma iron and induction of the Fenton chemistry and the Haber-Weiss reaction promoting formation of highly reactive free radicals such as the hydroxyl radical. Among available IV iron formulations, products with smaller carbohydrate shells are more labile and more likely to release labile iron directly into the plasma (i.e., before metabolism by the reticuloendothelial system). The proposed biologic targets of labile-iron-induced oxidative stress include nearly all systemic cellular components including endothelial cells, myocardium, liver as well as low density lipoprotein and other plasma proteins. Most studies have relied on plasma pharmacokinetic analyses that require many model assumptions to estimate contribution of the iron-carbohydrate complex to elevations in serum iron indices and hemoglobin. Additionally, the commercially available formulations have not been well studied with regard to optimal dosing regimens, long-term safety and comparative efficacy. The IV iron formulations fall into a class defined by the Food and Drug Administration as "Complex Drugs" and thus present considerable challenges for bioequivalence evaluation.

Quantification of Lipoteichoic Acid in Hemodialysis Patients With Central Venous Catheters

Hemodialysis patients with central venous catheters (CVCs) have chronic systemic inflammation, the source of which may be related to intraluminal bacterial biofilm. There is currently no non-invasive method to adequately evaluate intraluminal biofilm. Lipoteichoic acid (LTA) is a Gram-positive bacterial cell wall component that is spontaneously shed. The purpose of this study was to determine whether LTA could be quantified in biological samples and to evaluate potential relationships to markers of inflammation. Heparin-locked catheter aspirate was drawn from both the arterial and venous ports of each CVC prior to dialysis initiation. Venous blood from the dialysis circuit was collected 30 min after dialysis initiation. LTA was quantified in aspirate and plasma. Key markers of inflammation (interleukin-6, and hepcidin) and endothelial dysfunction (soluble vascular endothelial cadherin) were also determined in plasma samples. Catheter aspirate and systemic blood samples were obtained from 40 hemodialysis patients. The median (range) duration of catheter use was 130 (20–1635) days. Unexpectedly, median (range) plasma LTA concentrations (ng/mL) were significantly higher than catheter aspirate LTA concentrations [3.93 (0.25–15) vs. 2.38 (0.1–8.1), respectively, p = 0.01] in the majority (70%) of patients. Area under the receiver operator characteristic (ROC) curve showed good potential prognostic value of catheter aspirate LTA predicting systemic LTA concentrations with an area under the curve of 0.815 (95% CI, 0.68–0.95). A significant correlation was found between LTA and serum ferritin (r = 0.32, p = 0.04), however, there were no significant correlations between LTA and the other inflammation biomarkers assessed. LTA is quantifiable in aspirate and plasma of hemodialysis patients with CVCs and warrants further investigation to determine potential clinical application to intraluminal biofilm evaluation.

Fostering Innovation in Symptom Management among Hemodialysis Patients: Paths Forward for Insomnia, Muscle Cramps, and Fatigue

Individuals receiving in-center maintenance hemodialysis bear a high burden of both physical and mood symptoms. More than half of patients on hemodialysis report sleep disturbance, muscle cramps, and fatigue. Patients describe symptoms as having a deleterious effect on their quality of life, suggesting that symptom alleviation may meaningfully improve patient-reported outcomes. Moreover, patients on hemodialysis have identified symptom management as a key area for research and innovation, prioritizing symptom alleviation over other health outcomes such as mortality and biochemical indices. Despite the importance of symptoms to patients, there has been little research explicitly geared toward improving patient symptoms, and therefore minimal innovation in symptom management. In general, the physiologic underpinnings of symptoms are poorly understood, hampering the development of targeted therapies. In fact, there have been few drugs or devices approved by the US Food and Drug Administration for the indication of improving any patient-reported outcomes for patients on hemodialysis. Recognizing this gap in innovation, the Kidney Health Initiative, a public-private partnership between the American Society of Nephrology and US Food and Drug Administration, convened a workgroup to first prioritize symptoms for the development of therapeutic interventions, and then identify near-term actionable research goals for the prioritized physical symptoms of insomnia, muscle cramps, and fatigue. This paper summarizes the pathophysiology of the three prioritized symptoms, identifies key knowledge gaps, acknowledges factors that challenge development of new therapies, and offers the nephrology community actionable research goals for insomnia, muscle cramps, and fatigue.

Need for a Judicious Use of Nonsteroidal Anti-inflammatory Drugs to Avoid Community-Acquired Acute Kidney Injury

Millions of Americans use over-the-counter analgesics on a daily basis, and nearly 100 million nonsteroidal anti-inflammatory drug (NSAID) prescriptions are filled per year. In high-risk patients, these medications can disrupt kidney hemodynamics and precipitate community-acquired acute kidney injury (CA-AKI). The risk of NSAID-associated CA-AKI increases 3- to 5-fold in patients taking renin-angiotensin system inhibitors and diuretics concurrently. CA-AKI increases the risk of developing chronic kidney disease (CKD) or accelerating progression of pre-existing CKD. Importantly, many cases of NSAID-induced CA-AKI may be avoided by identifying high-risk patients and providing patient and provider education on when to avoid these medications and minimize risk.

In vitro and in vivo DFO-chelatable labile iron release profiles among commercially available intravenous iron nanoparticle formulations

Intravenous (IV) iron formulations are complex colloidal suspensions of iron oxide nanoparticles. Small changes in formulation can allow more labile iron to be released after injection causing toxicity. Thus, bioequivalence (BE) evaluation of generic IV iron formulations remains challenging. We evaluated labile iron release in vitro and in vivo using a high performance liquid chromatography chelatable iron assay to develop a relational model to support BE. In vitro labile iron release and in vivo labile iron pharmacokinetics were evaluated for Venofer^®, Ferrlecit^®, generic sodium ferric gluconate complex, InFeD^®, Feraheme^® and a pre-clinical formulation GE121333. Labile iron release profiles were studied in vitro in 150 mM saline and a biorelevant matrix (rat serum) at 0.952 mgFe/mL. In vivo plasma labile iron concentration-time profiles (t0-240 min) were studied in rats after a 40 mgFe/kg IV dose. In vitro labile iron release in saline was significantly higher compared to rat serum, especially with InFeD^®. An in vitro release constant (iKr) was calculated which correlated well with maximal plasma concentrations in the in vivo rat PK model (R² = 0.711). These data suggest an in vitro to in vivo correlation model of labile iron release kinetics could be applied to BE. Other generic IV iron formulations need to be studied to validate this model.

Symptom Prioritization among Adults Receiving In-Center Hemodialysis: A Mixed Methods Study

BACKGROUND AND OBJECTIVES

Individuals receiving in-center hemodialysis experience a high symptom burden that detrimentally affects their quality of life. There are few evidence-based interventions for symptom relief in this population. To stimulate innovation in symptom management, data on patient symptom prioritization and treatment preferences are needed. We undertook this study to (1) identify patient-prioritized symptoms for the development of symptom relief therapies and (2) elicit preferences for treatments among individuals receiving hemodialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a mixed methods study that included focus groups in Carrboro, North Carolina; Tucson, Arizona; and Seattle, Washington and a nationally distributed online survey. Focus group transcripts were analyzed for patterns, and the highest priority symptoms were determined on the basis of frequency and report severity. We used focus group findings to inform survey items. Focus group and survey results were crossvalidated and synthesized for final symptom prioritization.

RESULTS

There were 32 participants across three focus groups and 87 survey respondents from 27 states in the United States. The physical symptoms of insomnia, fatigue, muscle cramping, and nausea/vomiting and the mood symptoms of anxiety and depressed mood were reported by participants in all focus groups. Among survey respondents, fatigue (94%), cramping (79%), and body aches (76%) were the most common physical symptoms, and feeling depressed (66%), worried (64%), and frustrated (63%) were the most common mood symptoms. The top-prioritized symptoms were consistent across focus group and survey participants and included the physical symptoms insomnia, fatigue, and cramping and the mood symptoms anxiety, depression, and frustration. Participants indicated that symptom frequency, duration, unpredictability, and social and financial effects factored most heavily into symptom prioritization.

CONCLUSIONS

Patients prioritized the physical symptoms of insomnia, fatigue, and cramping and the mood symptoms of anxiety, depression, and frustration as the top symptoms for which to find new therapies.

Complexity of intravenous iron nanoparticle formulations: implications for bioequivalence evaluation

Intravenous iron formulations are a class of complex drugs that are commonly used to treat a wide variety of disease states associated with iron deficiency and anemia. Venofer® (iron-sucrose) is one of the most frequently used formulations, with more than 90% of dialysis patients in the United States receiving this formulation. Emerging data from global markets outside the United States, where many iron-sucrose similars or copies are available, have shown that these formulations may have safety and efficacy profiles that differ from the reference listed drug. This may be attributable to uncharacterized differences in physicochemical characteristics and/or differences in labile iron release. As bioequivalence evaluation guidance evolves, clinicians should be educated on these potential clinical issues before a switch to the generic formulation is made in the clinical setting.

How to select a nanosimilar

Nanomedicines in the class of nonbiological complex drugs (NBCDs) are becoming increasingly available. Up to 23 nanomedicines have been approved, and approximately 50 are in clinical development. Meanwhile, the first nanosimilars have entered the market through the generic approval pathway, but clinical differences have been observed. Many healthcare professionals may be unaware of this issue and must be informed of these clinically relevant variances. This article provides a tool for rational decision making for the inclusion of nanomedicines into the hospital formulary, including defined criteria for evaluation of substitutability or interchangeability. The tool was generated by conducting a roundtable with an international panel of experts and follows the same thought process that was developed and published earlier for the selection of biologicals/biosimilars. In addition to the existing criteria for biosimilars, a set of seven criteria was identified that specifically apply to nanosimilars. These include (1) particle size and size distribution, (2) particle surface characteristics, (3) fraction of uncaptured bioactive moiety, (4) stability on storage, (5) bioactive moiety uptake and (6) distribution, and (7) stability for ready-to-use preparation. Pharmacists should utilize their pharmaceutical expertise to use the appropriate criteria to evaluate the comparability of the drug to decide on interchangeability or substitutability.

Performance of Redox Active and Chelatable Iron Assays to Determine Labile Iron Release From Intravenous Iron Formulations

Emerging data from global markets outside the United States, where many generic iron sucrose formulations are available, have revealed that non‐US generic intravenous (i.v.) iron formulations may have iron release profiles that differ from the reference listed drug (RLD). The first generic i.v. iron approved in the United States was sodium ferric gluconate complex in 2011. We evaluated chelatable and redox labile iron assay methods to measure the amount of labile iron released from i.v. iron formulations in biorelevant matrices in vitro. The majority of published labile iron assays evaluated were not suitable for use in vitro due to overwhelming interference by the presence of the i.v. iron products. However, an optimized high‐performance liquid chromatography (HPLC)‐based method performed well for use in vitro labile iron detection in a biorelevant matrix. Application of this method may enhance bioequivalence evaluation of generic i.v. iron formulations in the future.

Drug Transporter Function--Implications in CKD

Drug transporters typically move substrates, including drugs, in an intracellular to extracellular direction and thus are efflux transporters. There is a small subset of transporters that move substrates in the opposite direction and are classified as influx transporters. Collectively, drug transporters contribute to the pharmacokinetic profile of a wide variety of drugs and other molecules including xenobiotics, metabolites, and endogenous solutes. Identification of genetic variants in the genes that encode these transporters is an emerging area of pharmacogenomics. Many polymorphisms of the multitude of genes that code for the transporters within the 2 major superfamilies (ATP-binding cassette transporters and solute carrier transporters) have been identified. Studies have shown that many single-nucleotide polymorphisms are associated with changes in protein expression, functionality, and drug exposure; however, there are limited data for most single-nucleotide polymorphisms and impact on clinical end points. Preliminary data suggest that patients with CKD may have reduced transporter function that may have effects on exposure and toxicity profiles. Additional research translating the functional significance of polymorphisms on clinical pharmacokinetics and relevant disease-specific end points will provide further understanding of the role of genetic variations in transporter genes.

Iron-based phosphate binders--a new element in management of hyperphosphatemia

INTRODUCTION

Management of serum phosphorus in patients with chronic kidney disease remains a significant clinical challenge. A pivotal component of the clinical approach to maintaining serum phosphorus concentrations towards the normal range is the use of phosphate binding agents in addition to comprehensive dietary counseling. The available agents work similarly by capitalizing on a cation within the agent to bind negatively charged phosphorus, forming an insoluble complex and reducing ingested phosphorus absorption. Despite several effective options for phosphate binder therapies, patient adherence remains an issue, mainly due to adverse effect profiles and large daily pill burdens.

AREAS COVERED

Two new iron-based phosphate binder therapies have recently become available in the United States, sucroferric oxyhydroxide and ferric citrate. These agents have both been shown to effectively reduce serum phosphorus comparably to widely used calcium-based binders and sevelamer salts.

EXPERT OPINION

The two new iron-based binders differ substantially with regard to phosphate binding chemistry and iron absorption profiles. Their place in therapy is still evolving and the impact of pill burden, gastrointestinal adverse effect profiles, potential cost reduction of anemia therapies and physiologic effects of long-term iron exposure need to be further evaluated.

Considerations and challenges in defining optimal iron utilization in hemodialysis

Trials raising concerns about erythropoiesis-stimulating agents, revisions to their labeling, and changes to practice guidelines and dialysis payment systems have provided strong stimuli to decrease erythropoiesis-stimulating agent use and increase intravenous iron administration in recent years. These factors have been associated with a rise in iron utilization, particularly among hemodialysis patients, and an unprecedented increase in serum ferritin concentrations. The mean serum ferritin concentration among United States dialysis patients in 2013 exceeded 800 ng/ml, with 18% of patients exceeding 1200 ng/ml. Although these changes are broad based, the wisdom of these practices is uncertain. Herein, we examine influences on and trends in intravenous iron utilization and assess the clinical trial, epidemiologic, and experimental evidence relevant to its safety and efficacy in the setting of maintenance dialysis. These data suggest a potential for harm from increasing use of parenteral iron in dialysis-dependent patients. In the absence of well powered, randomized clinical trials, available evidence will remain inadequate for making reliable conclusions about the effect of a ubiquitous therapy on mortality or other outcomes of importance to dialysis patients. Nephrology stakeholders have an urgent obligation to initiate well designed investigations of intravenous iron in order to ensure the safety of the dialysis population.

NSAID-avoidance education in community pharmacies for patients at high risk for acute kidney injury, upstate New York, 2011

INTRODUCTION

Nonsteroidal anti-inflammatory drugs (NSAIDs) are frequently associated with community-acquired acute kidney injury (AKI), a strong risk factor for development and progression of chronic kidney disease. Using access to prescription medication profiles, pharmacists can identify patients at high risk for NSAID-induced AKI. The primary objective of this analysis was to evaluate the effectiveness of a community pharmacy-based patient education program on patient knowledge of NSAID-associated renal safety concerns.

METHODS

Patients receiving prescription medications for hypertension or diabetes mellitus were invited to participate in an educational program on the risks of NSAID use. A patient knowledge questionnaire (PKQ) consisting of 5 questions scored from 1 to 5 was completed before and after the intervention. Information was collected on age, race, sex, and frequency of NSAID use.

RESULTS

A total of 152 participants (60% women) completed both the pre- and post-intervention questionnaire; average age was 54.6 (standard deviation [SD], 17.5). Mean pre-intervention PKQ score was 3.3 (SD, 1.4), and post-intervention score was 4.6 (SD, 0.9) (P = .002). Participants rated program usefulness (1 = not useful to 5 = extremely useful) as 4.2 (SD, 1.0). In addition, 48% reported current NSAID use and 67% reported that the program encouraged them to limit their use.

CONCLUSION

NSAID use was common among patients at high risk for AKI. A brief educational intervention in a community pharmacy improved patient knowledge on NSAID-associated risks. Pharmacists practicing in the community can partner with primary care providers in the medical home model to educate patients at risk for AKI.

Medication reconciliation and therapy management in dialysis-dependent patients: need for a systematic approach

Patients with ESRD undergoing dialysis have highly complex medication regimens and disproportionately higher total cost of care compared with the general Medicare population. As shown by several studies, dialysis-dependent patients are at especially high risk for medication-related problems. Providing medication reconciliation and therapy management services is critically important to avoid costs associated with medication-related problems, such as adverse drug events and hospitalizations in the ESRD population. The Medicare Modernization Act of 2003 included an unfunded mandate stipulating that medication therapy management be offered to high-risk patients enrolled in Medicare Part D. Medication management services are distinct from the dispensing of medications and involve a complete medication review for all disease states. The dialysis facility is a logical coordination center for medication management services, like medication therapy management, and it is likely the first health care facility that a patient will present to after a care transition. A dedicated and adequately trained clinician, such as a pharmacist, is needed to provide consistent, high-quality medication management services. Medication reconciliation and medication management services that could consistently and systematically identify and resolve medication-related problems would be likely to improve ESRD patient outcomes and reduce total cost of care. Herein, this work provides a review of available evidence and recommendations for optimal delivery of medication management services to ESRD patients in a dialysis facility-centered model.

Ferumoxytol: a silver lining in the treatment of anemia of chronic kidney disease or another dark cloud?

Intravenous iron therapy is pivotal in the treatment of anemia of chronic kidney disease to optimize the response of hemoglobin to erythropoiesis-stimulating agents. Intravenous iron use in patients with chronic kidney disease is on the rise. Recent clinical trial data prompting safety concerns regarding the use of erythropoiesis-stimulating agents has stimulated new US Food and Drug Administration label changes and restrictions for these agents, and has encouraged more aggressive use of intravenous iron. The currently available intravenous iron products differ with regard to the stability of the iron-carbohydrate complex and potential to induce hypersensitivity reactions. Ferumoxytol is a newer large molecular weight intravenous iron formulation that is a colloidal iron oxide nanoparticle suspension coated with polyglucose sorbitol carboxymethyl ether. Ferumoxytol has robust iron-carbohydrate complex stability with minimal dissociation or appearance of free iron in the serum, allowing the drug to be given in relatively large doses with a rapid rate of administration. Clinical trials have demonstrated the superior efficacy of ferumoxytol versus oral iron with minimal adverse effects. However, recent postmarketing data have demonstrated a risk of hypersensitivity that has prompted new changes to the product information mandated by the Food and Drug Administration. Additionally, the long-term safety of this agent has not been evaluated, and its place in the treatment of anemia of chronic kidney disease has not been fully elucidated.

Medication-related problems in CKD

Patients with CKD are often prescribed heterogeneous medications to treat disease-associated comorbidities, to slow down progression of the disease, and to minimize morbidity and mortality rates. However, the medication regimens of this population are very complex, leading to an increased potential for medication-related problems (MRPs). As kidney function declines, the type and amount of medications a patient consumes increases, thereby putting them at a higher risk for MRPs. MRPs have been known to be associated with morbidity, mortality, and a lower quality of life. This review will summarize data on the prevalence and effect of MRPs, and strategies that can be used by clinicians to reduce and resolve MRPs.

Plasma pharmacokinetics of two consecutive doses of ferumoxytol in healthy subjects

Intravenous (IV) iron is used to treat iron-deficiency anemia in patients with chronic kidney disease (CKD). Ferumoxytol is a novel iron formulation administered rapidly as two IV boluses of 510 mg each. In this placebo-controlled, double-blind, parallel-group study, 58 healthy volunteers received ferumoxytol in two 510 mg doses administered 24 h apart. Population pharmacokinetics (PK) analysis was conducted, and a two-compartment open model with zero-order input and Michaelis-Menten elimination was found to best describe the data. The population mean estimates for volume of distribution of the central compartment (V(1)), maximal elimination rate (V(max)), and ferumoxytol concentration at which rate of metabolism would be one-half of V(max) (K(m)) were 2.71 l, 14.3 mg/h, and 77.5 mg/l, respectively. When the effect of body weight on V(1) was added in the analysis, interindividual variability was found to be reduced. A noncompartmental analysis of two simulated 510-mg ferumoxytol doses was also performed to provide clinically interpretable data on half life and exposure. Ferumoxytol given as two consecutive 510-mg doses was well tolerated.

Reduced drug use and hospitalization rates in patients undergoing hemodialysis who received pharmaceutical care: a 2-year, randomized, controlled study

STUDY OBJECTIVE

To investigate the impact of a pharmaceutical care program managed by clinical pharmacists on drug use, drug costs, hospitalization rates, and drug-related problems (DRPs) in ambulatory patients undergoing hemodialysis.

DESIGN

Prospective, randomized, controlled, longitudinal, 2-year pilot study.

SETTING

Nonprofit university-affiliated dialysis clinic.

PATIENTS

One hundred four patients older than 18 years with end-stage renal disease (ESRD) who were undergoing a stable hemodialysis regimen for at least 3 months.

INTERVENTION

Patients were randomly assigned to receive either pharmaceutical care, consisting of one-on-one care, with in-depth drug therapy reviews conducted by a clinical pharmacist (57 patients), or standard of care, consisting of brief drug therapy reviews conducted by a nurse (47 patients).

MEASUREMENTS AND MAIN RESULTS

Baseline data on demographic and clinical characteristics were collected. Mean numbers of concomitant drugs, drug costs, hospitalization rates, and lengths of stay were compared between the groups. In the pharmaceutical care group, DRPs were identified and recorded. Baseline age, length of time receiving hemodialysis, and etiology of ESRD were not significantly different between the groups. Mean number of concomitant drugs at baseline was similar between the groups. At the end of the 2-year follow-up, pharmaceutical care was associated with a significant decrease of 14% fewer drugs compared with standard of care, as documented during each drug therapy review (p<0.05). There were significantly fewer all-cause hospitalizations among patients assigned to pharmaceutical care compared with those receiving standard of care (mean +/- SD 1.8 +/- 2.4 vs 3.1 +/- 3 hospitalizations, p=0.02), and the cumulative time hospitalized was shorter in the pharmaceutical care group compared with the standard of care group (9.7 +/- 14.7 vs 15.5 +/- 16.3 days, p=0.06). During the study period, 530 DRPs were identified and resolved.

CONCLUSION

Identification and resolution of DRPs through pharmaceutical care resulted in decreased drug use and costs for patients undergoing hemodialysis. Hospitalization rates were significantly lower in the pharmaceutical care group, with a trend toward shorter duration. Provision of pharmaceutical care is associated with tangible benefits on outcomes in ambulatory patients undergoing hemodialysis and should be considered in health care policy decisions.

Estimation of creatinine clearance in morbidly obese patients

PURPOSE

Estimates of creatinine clearance (CL(cr)) based on equations and various body-size descriptors were compared with 24-hour measured CL(cr) values in morbidly obese patients.

METHODS

Patients age 18-75 years with a body mass index (BMI) of >/=40 kg/m(2) with stable serum creatinine values were enrolled. Covariates known to contribute to alteration in CL(cr) were used to exclude patients. Twenty-four-hour urine collection was performed to measure CL(cr). Bioelectric impedance analysis was used to estimate fat-free weight (FFW). Glomerular filtration rate was estimated using the four-variable Modification of Diet in Renal Disease (MDRD4) equation. CL(cr) was estimated using the Cockcroft-Gault and Salazar-Corcoran methods using total body weight (TBW). Body-size descriptors, such as ideal body weight (IBW), adjusted body weight (ABW), and lean body weight (LBW), and FFW were substituted in the Cockcroft-Gault equation to generate additional estimates of CL(cr).

RESULTS

Fifty-four patients (mean +/- S.D. age, 48.4 +/- 12.9 years; TBW, 142.3 +/- 41.7 kg; BMI, 50.5 +/- 12.6 kg/m(2)) completed the study. All three equations were biased in their estimation of CL(cr). Use of MDRD4 and IBW in the Cockcroft-Gault equation underestimated CL(cr), while the Salazar-Corcoran equation and use of TBW or ABW in the Cockcroft-Gault equation overestimated this value. Substitution of fat-free weight or LBW in the Cockcroft-Gault equation provided unbiased estimates of CL(cr).

CONCLUSION

An LBW estimate, based on TBW and BMI, incorporated into the Cockcroft-Gault equation provided an unbiased, relatively precise, accurate, and clinically practical estimate of 24-hour measured CL(cr) in morbidly obese patients.

Oxidative Stress and Inflammation in Chronic Kidney Disease: Role of Intravenous Iron and Vitamin D

Cardiovascular disease (CVD) is the leading cause of death among chronic kidney disease patients (CKD). The etiology of CVD in CKD is multifactorial and increasing evidence points to the important contribution of “nontraditional” risk factors including oxidative stress and inflammation. CKD is associated with a chronic imbalance of prooxidant and antioxidant factors that results in a state of chronic inflammation. Intravenous iron supplementation has been shown to induce oxidative stress and has been associated with lipid peroxidation and DNA damage. Conversely, treatment with vitamin D analogs has been associated with improved mortality in hemodialysis patients in 2 recent large cohort studies. These data suggest that vitamin D analogs may exert effects beyond their pharmacologic role in parathyroid hormone suppression. This article addresses the current data regarding the relative contributions of intravenous iron supplementation and vitamin D analog therapy on oxidative stress and inflammation in CKD patients.

Comparison of Oxidative Stress Markers After Intravenous Administration of Iron Dextran, Sodium Ferric Gluconate, and Iron Sucrose in Patients Undergoing Hemodialysis

STUDY OBJECTIVE

To compare non-transferrin-bound iron and markers of oxidative stress after single intravenous doses of iron dextran, sodium ferric gluconate, and iron sucrose.

DESIGN

Prospective, open-label, crossover study.

SETTING

University-affiliated general clinical research center.

PATIENTS

Twelve ambulatory patients undergoing hemodialysis.

INTERVENTION

Patients received 100 mg of intravenous iron dextran, sodium ferric gluconate, and iron sucrose in random sequence, with a 2-week washout period between treatments.

MEASUREMENTS AND MAIN RESULTS

Serum samples for transferrin saturation, non-transferrin-bound iron, and malondialdehyde (MDA; marker of lipid peroxidation) were obtained before (baseline) and 30, 60, 120, and 360 minutes and 2 weeks after each iron infusion. A serum sample for hemeoxygenase-1 (HO-1) RNA was obtained at baseline and 360 minutes after infusion. Non-transferrin-bound iron values were significantly higher 30 minutes after administration of sodium ferric gluconate and iron sucrose compared with iron dextran (mean +/- SEM 10.1 +/- 2.2, 3.8 +/- 0.8, and 0.23 +/-0.1 microM, respectively, p<0.001 for sodium ferric gluconate vs iron dextran, p = 0.002 for iron sucrose vs iron dextran). A significant positive correlation was noted between transferrin saturation and the presence of non-transferrin-bound iron for sodium ferric gluconate and iron sucrose (r2 = 0.37 and 0.45, respectively, p<0.001) but not for iron dextran (r2 = 0.09). After sodium ferric gluconate, significantly more samples showed increases in MDA levels from baseline compared with iron sucrose and iron dextran (p = 0.006); these increased levels were associated with the presence of non-transferrin-bound iron, baseline transferrin saturation above 30%, baseline transferrin levels below 180 mg/dl, and ferritin levels above 500 ng/ml (p<0.05). However, only a transferrin level below 180 mg/dl was independently associated (odds ratio 4.8, 95% confidence interval 1.2-15.3).

CONCLUSION

Iron sucrose and sodium ferric gluconate were associated with greater non-transferrin-bound iron appearance compared with iron dextran. However, only sodium ferric gluconate showed significant increases in lipid peroxidation. The relationship between non-transferrin-bound iron from intravenous iron and oxidative stress warrants further exploration.

Non-transferrin-bound iron is associated with enhanced Staphylococcus aureus growth in hemodialysis patients receiving intravenous iron sucrose

BACKGROUND

Hemodialysis vascular access infections are most frequently caused by Staphylococcus spp. The purpose of this study was to determine if S. aureus growth is enhanced after administration of IV iron sucrose and to establish a relationship between the appearance of non-transferrin-bound iron (NTBI) and S. aureus growth.

METHODS

Serum samples were obtained from 12 hemodialysis patients receiving maintenance doses of 100 mg of iron sucrose at baseline and 5, 30, 90, 220 min and 48 h after iron administration. Assays for NTBI and transferrin saturation were performed. S. aureus isolates were used to inoculate patient serum samples. Bacterial growth was determined by optical density.

RESULTS

Six of 12 patients had NTBI present within 30 min of the iron dose. NTBI was present more frequently in patients with baseline transferrin saturation values >30% (p < 0.05). Bacterial growth was significantly greater in patients who had NTBI present at 5, 90 and 220 min after iron administration compared to those who did not have NTBI present.

CONCLUSIONS

Doses of 100 mg of iron sucrose are associated with the presence of NTBI and enhanced S. aureus growth.

Sampling for international normalized ratios in patients on hemodialysis with central venous catheters

The primary objectives of this study were to evaluate the effect of varying heparin concentrations on International Normalized Ratio values and to assess the accuracy of these values deter mined through the arterial line of the dialysis circuit Twenty-two patients on hemodialysis with central venous catheters were studied After a peripheral venipuncture, timed samples from the arterial line of the hemodialysis circuit were obtained after dialysis was initiated and prior to initiating heparin. Assays for coagulation parameters were performed. There was no signifcant difference in any coagulation parameter measured from the arterial line samples compared to the venipuncture samples. Serial heparin dilutions in vitro demonstrated that residual amounts of heparin in the central venous catheter may falsely elevate International Normalized Ratio values. This study demonstrates that accurate International Normalized Ratio values in patients on hemodialysis with heparinized central venous catheters can be obtained ericiently and cost-effectively from the arterial line within 1 minute of dialysis initiation.

Optimizing antimicrobial therapy for gram-positive bloodstream infections in patients on hemodialysis

Infections with gram-positive organisms are highly prevalent in hemodialysis patients and are a major cause of morbidity and mortality in this population. Antimicrobial therapy is widely used to treat these infections, and prolonged therapy with these agents is often necessary. Extensive use of antimicrobials in hemodialysis patients has resulted in a growing threat of resistance, especially among gram-positive bacteria such as Enterococcus spp and Staphylococcus aureus. Vancomycin-resistant enterococci and S. aureus isolates with reduced susceptibility to vancomycin are increasingly being reported in hemodialysis patients. Additionally, resistance of these organisms to newer agents, such as linezolid and daptomycin, has been documented. Appropriate utilization of antimicrobial therapy to treat these organisms requires an understanding of the pharmacokinetic and pharmacodynamic principles to optimize therapy and avoid adverse drug events. The pharmacokinetic and pharmacodynamic profile of antimicrobial agents can be significantly altered in patients with chronic kidney disease. This review will describe mechanisms of antimicrobial resistance among common gram-positive organisms. The pharmacokinetic and pharmacodynamic principles of cephalosporins, vancomycin, aminoglycosides, linezolid, and daptomycin and applications for use of these agents in the treatment of patients with bloodstream infections on hemodialysis are discussed.

Vancomycin dosing in high flux hemodialysis: a limited-sampling algorithm

PURPOSE

The feasibility of using a limited-sampling algorithm for administration of vancomycin for treatment of vascular-access-related bacteremia in outpatient high flux hemodialysis was investigated.

METHODS

The original vancomycin-dosing algorithm used at our hemodialysis unit required stat orders for serum vancomycin concentrations before each hemodialysis session to determine the dose of vancomycin to be administered posthemodialysis. Vancomycin concentration data obtained using this original algorithm from January through September 2001 were retrospectively analyzed to determine how many vancomycin concentrations measured 5-20 microg/mL and identify potential clinical predictors of vancomycin removal.

RESULTS

A total of 409 serum vancomycin concentrations were drawn during the study period. Ninety-seven percent of concentrations drawn were within 5-20 microg/mL. Twenty-eight patients had data evaluable to determine pharmacokinetic parameters. Mean +/- S.D. vancomycin removal was 39% +/- 13%. Body weight and duration of dialysis alone, blood flow rate, and dialysate flow rate were not predictive of vancomycin removal. Based on these data, a revised algorithm with limited vancomycin sampling data was initiated in December 2002. Retrospective analysis of concentrations obtained and achieved by this algorithm demonstrated a 70% reduction in the number of vancomycin concentration determinations, with 93% of these concentrations within 5-20 microg/mL. The estimated annual cost saving to the hemodialysis unit with the revised algorithm was 7552 dollars.

CONCLUSION

A vancomycin-dosing algorithm using limited concentration monitoring for hemodialysis patients achieved comparable vancomycin concentrations to those found with more frequent monitoring and resulted in significant cost savings.

The role of sevelamer in achieving the kidney disease outcomes quality initiative (K/DOQI) guidelines for hyperphosphatemia

BACKGROUND

End-stage renal disease (ESRD) is a chronic health care problem associated with multiple co-morbidities and escalating costs. Disregulation of mineral metabolism (principally hyperphosphatemia and hypercalcemia) contributes to substantial morbidity and mortality. Accordingly, new and more-aggressive Kidney Disease Outcomes Quality Initiative (K/DOQI) Guidelines from the National Kidney Foundation promote lower serum phosphorus (3.5-5.5 mg/dL), lower calcium (8.4-9.5 mg/dL), and lower calcium-phosphorus product (< 55 mg(2)/dL(2)) targets.

REVIEW FINDINGS

Traditional calcium-based and metal-based phosphate binders are effective but are associated with side effects and toxicity that limit their use. Achieving rigorous K/DOQI goals demands higher therapeutic doses of phosphate binders and may require more-aggressive use of calcium-free and metal-free phosphate binders. Sevelamer hydrochloride is a calcium- and metal-free polymer that binds phosphate effectively without contributing to calcium load or metal accumulation. In the Treat-to-Goal trial, sevelamer-treated dialysis patients had less progression of coronary and aortic calcification than patients treated with calcium-based binders. This offers the potential promise of reducing cardiovascular morbidity and mortality. The 800-mg tablet (Renagel) increases the daily sevelamer dose while reducing the number of tablets required per meal. Nine of the 800-mg tablets per day (3 x 800-mg tablets tid with meals) of sevelamer monotherapy have been shown to achieve K/DOQI serum phosphorus and calcium-phosphorus product targets.

CONCLUSION

In summary, this review of the current evidence-base concludes that the new, more-aggressive, K/DOQI goals limit the use of metal-based and calcium-based phosphate binders. Sevelamer offers the advantages of lowering serum phosphorus without the risks of calcium or metal accumulation - and offers the promise of slowing the progression of vascular calcification and potentially reducing the morbidity and mortality of hemodialysis patients.