Drug dosing in chronic kidney disease

International Renal Interest Society best practice consensus guidelines for the diagnosis and management of acute kidney injury in cats and dogs

Acute kidney injury (AKI) is defined as an injury to the renal parenchyma, with or without a decrease in kidney function, as reflected by accumulation of uremic toxins or altered urine production (i.e., increased or decreased). AKI might result from any of several factors, including ischemia, inflammation, nephrotoxins, and infectious diseases. AKI can be community- or hospital-acquired. The latter was not previously considered a common cause for AKI in animals; however, recent evidence suggests that the prevalence of hospital-acquired AKI is increasing in veterinary medicine. This is likely due to a combination of increased recognition and awareness of AKI, as well as increased treatment intensity (e.g., ventilation and prolonged hospitalization) in some veterinary patients and increased management of geriatric veterinary patients with multiple comorbidities. Advancements in the management of AKI, including the increased availability of renal replacement therapies, have been made; however, the overall mortality of animals with AKI remains high. Despite the high prevalence of AKI and the high mortality rate, the body of evidence regarding the diagnosis and the management of AKI in veterinary medicine is very limited. Consequently, the International Renal Interest Society (IRIS) constructed a working group to provide guidelines for animals with AKI. Recommendations are based on the available literature and the clinical experience of the members of the working group and reflect consensus of opinion. Fifty statements were generated and were voted on in all aspects of AKI and explanatory text can be found either before or after each statement.

Development of a list with renally relevant drugs as a tool to increase medicines optimisation in patients with chronic kidney disease

OBJECTIVES

Chronic kidney disease (CKD) is a common disorder all over the world. Therapeutic goals are early detection of declining renal function and implementation of adequate pharmacological treatments regarding underlying and secondary diseases. As therapy becomes more complex with increasing stages of CKD, a decision-making tool for healthcare professionals could help to ensure safe drug treatment in patients with CKD in the outpatient setting. Therefore, a list of renally relevant drugs as a decision-making tool was developed to improve medicines optimisation for CKD patients in the outpatient setting long term.

METHODS

A renally relevant drug list (RRD-list) with renally relevant drugs, based on data from a study on medicines optimisation in patients with CKD from June 2015 to March 2018, was developed at the nephrological outpatient clinic at the Klinikum Fulda, Germany. The whole study is published elsewhere. A clinical pharmacist reviewed the patients' medications, current drug-related problems and all nephrologists' recommendations, and categorised all detected drugs into renally relevant and non-renally relevant groups. The 10 most frequently detected renally relevant drug groups were summarised in the RRD-list and extended by treatment alternatives and advice.

RESULTS

The medication of 160 patients, who were receiving overall 1376 drugs, was analysed; 831 drugs were defined as renally relevant. Drug-related problems were caused by 543 renally relevant drugs. The nephrologists made 292 recommendations regarding 28 drug classes. Considering the 10 most frequent drug groups, in total 16 renally relevant drug groups with 36 drug classes were added to the RRD-list.

CONCLUSIONS

The RRD-list could be an essential tool for all healthcare professionals in their daily work, such as general practitioners and community pharmacists, for the treatment of patients with renal insufficiency.

Assessing the binding interaction of polystyrene sulfonate with amitriptyline in healthy volunteers: a cross-over design - The BIND study

PURPOSE

Polystyrene sulfonate is used for binding potassium in patients with chronic kidney disease (CKD). Because of its binding properties, it can potentially bind other medications and thereby decrease their bioavailability and effectiveness. Amitriptyline, often used by CKD patients for neuropathic pain, shows significant binding to polystyrene sulfonate in vitro. The purpose of this study was to determine the effect of polystyrene sulfonate on the exposure of amitriptyline in vivo when taken concomitantly in healthy volunteers.

METHODS

We performed a prospective cross-over study in nine healthy volunteers. Participants were 18 years of age or older, did not use any medication, and had no known allergy to amitriptyline or polystyrene sulfonate. Participants visited Deventer Teaching Hospital twice. Once they received a single dose of amitriptyline 50 mg and once they received a single dose of both polystyrene sulfonate 15 g and amitriptyline 50 mg taken concomitantly, with a wash out period of at least 1 week. After intake of the medication, six blood samples were collected, at 2, 3, 4, 5, 6, and 8 h. Blood samples were analysed to determine maximum concentration (Cmax) and area under the curve 0-8 h after intake (AUC_0-8 h). Difference in Cmax and AUC_0-8 h was analysed with a paired T-test or Wilcoxon signed rank test, depending on normality of the data. A p-value < 0.05 was considered statistically significant.

RESULTS

Of the nine participants included, eight participants completed both visits to the hospital. Mean maximum concentration (Cmax) of amitriptyline was 35.61 µg l^-1 (95% CI 27.90-43.33 µg l^-1) when taken alone, compared to 9.25 µg l^-1 (95% CI 6.59-11.92 µg l^-1) when taken with polystyrene sulfonate (p < 0.001). Mean AUC_0-8 h of amitriptyline was 168.20 µg × h l^-1 (95% CI 139.95-196.45 µg × h l^-1) when taken alone and 45.78 µg × h l^-1 (95% CI 30.20-61.36 µg × h l^-1) when taken with polystyrene sulfonate (p < 0.0001).

CONCLUSION

These results show a significant decrease in exposure of amitriptyline of approximately 75% when taken concomitantly with polystyrene sulfonate, thereby probably compromising therapy efficacy. Patients using both amitriptyline and polystyrene sulfonate should be informed to separate intake of these medications.

TRIAL REGISTRATION

NL8539 (17 April 2020).

Drug-Dosing Adjustment in Dogs and Cats with Chronic Kidney Disease

Chronic kidney disease is a common kidney disorder in adult and aged dogs and cats; the management of associated complications and comorbidities generally requires a life-long medical treatment to ensure a good quality of life of affected patients. However, indications and the literature on drug dosing in dogs and cats with chronic kidney disease are often lacking. The aim of this review is to revise the current literature on drug dosing in canine and feline patients with renal impairment, with a special focus on the most commonly used medications to manage chronic kidney disease and possible comorbidities.

Pharmacokinetics in children with chronic kidney disease

In children, the main causes of chronic kidney disease (CKD) are congenital diseases and glomerular disorders. CKD is associated with multiple physiological changes and may therefore influence various pharmacokinetic (PK) parameters. A well-known consequence of CKD on pharmacokinetics is a reduction in renal clearance due to a decrease in the glomerular filtration rate. The impact of renal impairment on pharmacokinetics is, however, not limited to a decreased elimination of drugs excreted by the kidney. In fact, renal dysfunction may lead to modifications in absorption, distribution, transport, and metabolism as well. Currently, insufficient evidence is available to guide dosing decisions on many commonly used drugs. Moreover, the impact of maturation on drug disposition and action should be taken into account when selecting and dosing drugs in the pediatric population. Clinicians should take PK changes into consideration when selecting and dosing drugs in pediatric CKD patients in order to avoid toxicity and increase efficiency of drugs in this population. The aim of this review is to summarize known PK changes in relation to CKD and to extrapolate available knowledge to the pediatric CKD population to provide guidance for clinical practice.

Once- versus twice-weekly carfilzomib in relapsed and refractory multiple myeloma by select patient characteristics: phase 3 A.R.R.O.W. study subgroup analysis

The phase 3 A.R.R.O.W. study demonstrated that treatment with once-weekly carfilzomib (70 mg/m2) and dexamethasone (once-weekly Kd70 mg/m2) improved progression-free survival compared with twice-weekly carfilzomib (27 mg/m2) and dexamethasone (twice-weekly Kd27 mg/m2) in patients with relapsed and refractory multiple myeloma (RRMM; median, 11.2 versus 7.6 months; hazard ratio [HR] = 0.69; 95% confidence interval, 0.54-0.88; P = 0.0029). Once-weekly dosing also improved response rates and depth of response. We performed a subgroup analysis from A.R.R.O.W. according to age (<65, 65-74, or ≥75 years), renal function (creatinine clearance <50, ≥50-<80, or ≥80 mL/min), number of prior therapies (2 or 3), and bortezomib-refractory status (yes or no). Compared with twice-weekly Kd27 mg/m2, once-weekly Kd70 mg/m2 reduced the risk of progression or death (HR = 0.60-0.85) and increased overall response rates in nearly all the examined subgroups, consistent with reports in the overall A.R.R.O.W. population. The safety profiles of once-weekly Kd70 mg/m2 across subgroups were also generally consistent with those in the overall population. Findings from this subgroup analysis generally demonstrate a favorable benefit-risk profile of once-weekly Kd70 mg/m2, further supporting once-weekly carfilzomib dosing as an appropriate treatment option for patients with RRMM, regardless of baseline patient and disease characteristics.

Antidepressant Usage in Haemodialysis Patients: Evidence of Sub-Optimal Practice Patterns

BACKGROUND

Depression is common in patients on haemodialysis and associated with adverse outcomes. Antidepressant use is widespread though evidence of efficacy is limited.

OBJECTIVES

To study antidepressant management practices in patients on haemodialysis with reference to NICE guidelines on management of depression in adults with chronic physical health problems.

DESIGN

Prospective, multicentre, longitudinal cohort study with 6-15 month follow-up.

PARTICIPANTS

Patients on haemodialysis established on antidepressant medication.

MEASUREMENTS

Baseline assessment of mood was undertaken using Beck Depression Inventory (BDI-II). Demographic, clinical and medication data were also collected. Changes in clinical and life circumstances and medication during follow-up were recorded. At follow-up, BDI-II was reassessed and diagnostic psychiatric assessment undertaken.

RESULTS

Forty-one patients were studied. General practitioners were the main prescribers (68%). Ten agents were in use, the commonest being Citalopram (39%). Doses were often suboptimal. At baseline, 30 patients had high BDI-II scores (≥16) and 22 remained high at follow-up. Eleven had BDI-II < 16 at baseline. In five, this increased on follow-up to ≥16. Sixteen patients (39%) had no medication review during follow-up, 14 (34%) had a dose review, and 11 (27%) a medication change. On psychiatric assessment at follow-up, eight patients had current major depressive disorder (MDD), seven recurrent and 20 evidence of past MDD. Six displayed no evidence of ever having MDD.

CONCLUSIONS

Antidepressant management in patients on haemodialysis reflected poor drug selection, overprescription, under-dosing and inadequate follow-up suggesting sub-optimal adherence to NICE guidelines. Most patients had high depression scores at follow-up. Antidepressant use in haemodialysis requires reappraisal.

Pharmacotherapeutic Management of Neuropathic Pain in End-Stage Renal Disease

Background

Chronic noncancer pain is pervasive throughout the general patient population, transcending all chronic disease states. Patients with end-stage renal disease (ESRD) present a complicated population for which medication management requires careful consideration of the pathogenesis of ESRD and intimate knowledge of pharmacology. The origin of pain must also guide treatment options. As such, the presentation of neuropathic pain in ESRD can present a challenging case. The authors aim to provide a review of available classes of medications and considerations for the treatment of neuropathic pain in ESRD.

Summary

In this narrative review, the authors discuss important strategies and considerations for the treatment of neuropathic pain in ESRD, including the pathogenesis of neuropathic pain, physiological changes for consideration in ESRD patients, and disease-specific consideration for medication selection. Pharmacotherapeutic classes discussed include: anticonvulsants, antiarrhythmics, antidepressants, topicals, and opioids.

Key Message

Pain management in ESRD patients requires careful assessment of drug-specific properties, accumulation, metabolism (presence of active/toxic metabolites), extraction by dialysis, and presence of drug - drug interactions. In the absence of pharmacokinetic data in ESRD patients, therapeutic window and potential risks should be factored in the decision making along with continued monitoring throughout therapy.

Carfilzomib vs bortezomib in patients with multiple myeloma and renal failure: a subgroup analysis of ENDEAVOR

In ENDEAVOR, carfilzomib (56 mg/m²) and dexamethasone (Kd56) demonstrated longer progression-free survival (PFS) over bortezomib and dexamethasone (Vd) in patients with relapsed/refractory multiple myeloma (RRMM). Here we evaluated Kd56 vs Vd by baseline renal function in a post hoc exploratory subgroup analysis. The intent-to-treat population included 929 patients (creatinine clearance [CrCL] ≥15 to <50 mL/min, n = 85 and n = 99; CrCL 50 to <80 mL/min, n = 186 and n = 177; and CrCL ≥80 mL/min, n = 193 and n = 189 for Kd56 and Vd arms, respectively). In these respective subgroups, median PFS was 14.9 vs 6.5 months (hazard ratio [HR], 0.49; 95% confidence interval [CI], 0.320-0.757), 18.6 vs 9.4 months (HR, 0.48; 95% CI, 0.351-0.652), and not reached (NR) vs 12.2 months (HR, 0.60; 95% CI, 0.434-0.827) for those receiving Kd56 vs Vd, respectively; median overall survival (OS) was 42.1 vs 23.7 months (HR, 0.66; 95% CI, 0.443-0.989), 42.5 vs 32.8 months (HR, 0.83; 95% CI, 0.626-1.104), and NR vs 42.3 months (HR, 0.75; 95% CI, 0.554-1.009). Complete renal response (ie, CrCL improvement to ≥60 mL/min in any 2 consecutive visits if baseline CrCL <50 mL/min) rates were 15.3% (95% CI, 8.4-24.7) and 14.1% (95% CI, 8.0-22.6) for those receiving Kd56 vs Vd, respectively. In a combined Kd56 and Vd analysis, complete renal responders had longer median PFS (14.1 vs 9.4 months; HR, 0.805; 95% CI, 0.438-1.481) and OS (35.3 vs 29.7 months; HR, 0.91; 95% CI, 0.524-1.577) vs nonresponders. Grade ≥3 adverse event rates in the respective subgroups were 87.1% vs 79.4%, 84.4% vs 71.8%, and 77.1% vs 65.9% for those receiving Kd56 vs Vd, respectively. Thus, Kd56 demonstrated PFS and OS improvements over Vd in RRMM patients regardless of their baseline renal function. The ENDEAVOR trial was registered at www.clinicaltrials.gov as #NCT01568866.

Emergency medicine evaluation and management of the end stage renal disease patient

BACKGROUND

End stage renal disease (ESRD) is increasing in the U.S., and these patients demonstrate greater all-cause mortality, cardiovascular events, and hospitalization rates when compared to those with normal renal function. These patients may experience significant complications associated with loss of renal function and dialysis.

OBJECTIVE

This review evaluates complications of ESRD including cardiopulmonary, neurologic, infectious disease, vascular, and access site complications, as well as medication use in this population.

DISCUSSION

ESRD incidence is rapidly increasing, and patients commonly require renal replacement therapy including hemodialysis (HDS) or peritoneal dialysis (PD), each type with specific features. These patients possess greater risk of neurologic complications, cardiopulmonary pathology, infection, and access site complications. Focused history and physical examination are essential. Neurologic issues include uremic encephalopathy, cerebrovascular pathology, and several others. Cardiopulmonary complications include pericarditis, pericardial effusion/tamponade, acute coronary syndrome, sudden cardiac death, electrolyte abnormalities, pulmonary edema, and air embolism. Infections are common, with patients more commonly presenting in atypical fashion. Access site infections and metastatic infections must be treated aggressively. Access site complications include bleeding, aneurysm/pseudoaneurysm, thrombosis/stenosis, and arterial steal syndrome. Specific medication considerations are required for analgesics, sedatives, neuromuscular blocking agents, antimicrobials, and anticoagulants.

CONCLUSIONS

Consideration of renal physiology with complications in ESRD can assist emergency providers in the evaluation and management of these patients. ESRD affects many organ systems, and specific pharmacologic considerations are required.

Pharmacokinetics and safety of carfilzomib in patients with relapsed multiple myeloma and end-stage renal disease (ESRD): an open-label, single-arm, phase I study

Purpose

The pharmacokinetics (PK) of carfilzomib have been previously studied in multiple myeloma patients with varying degrees of renal impairment (normal, mild, moderate, severe, and end-stage renal disease [ESRD]) at doses of 15 and 20 mg/m². This study evaluated carfilzomib PK at higher doses of 27 and 56 mg/m² in normal renal function and ESRD patients.

Methods

Patients received carfilzomib on two consecutive days/week for 3 weeks every 28-day cycle: 20 mg/m² (cycle 1 day 1–2), escalated to 27 mg/m² on cycle 1 day 8; if tolerated, 56 mg/m² starting cycle 2 day 1. The primary objective was PK assessment with safety/tolerability and response rate as secondary and exploratory objectives, respectively.

Results

26 patients were enrolled (15 normal, 11 ESRD). There was a trend toward higher area under the concentration time curve (AUC) and maximum concentration in ESRD versus normal renal function patients; however, high interpatient PK variability was discerned. Relative to patients with normal renal function, ESRD patients showed 33% higher AUC. Overall response rate was 43% for the normal renal function and 60% for the ESRD groups. Safety findings were generally similar between the two groups and consistent with the known safety profile of carfilzomib in multiple myeloma patients.

Conclusion

There were no meaningful differences in PK between patients with normal renal function and ESRD in light of carfilzomib exposure–response relationships. These results continue to support dosing recommendation that no starting dose adjustment of carfilzomib appears warranted in patients with baseline renal impairment.

Effects of High Density Lipoprotein Raising Therapies on Cardiovascular Outcomes in Patients with Type 2 Diabetes Mellitus, with or without Renal Impairment: The Action to Control Cardiovascular Risk in Diabetes Study

BACKGROUND

The role of high density lipoprotein-raising interventions in addition to statin therapy in patients with diabetes remains controversial. Chronic kidney disease (CKD) is a strong modifier of cardiovascular (CV) outcomes. We therefore investigated the impact of CKD status at baseline on outcomes in patients with diabetes randomized to standard statin or statin plus fenofibrate treatment in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) lipid trial.

METHODS

Among 5,464 participants in the ACCORD lipid trial, 3,554 (65%) were free of CKD at baseline, while 1,910 (35%) had mild to moderate CKD. Differences in CV outcomes during follow-up between CKD and non-CKD subgroups were examined. In addition, the effect of fenofibrate as compared to placebo on CV outcomes was examined for both subgroups.

RESULTS

All CV outcomes were 1.4-3 times higher among patients with CKD as compared to non-CKD patients. In patients with CKD, the addition of fenofibrate had no effect on any of the primary or secondary outcomes. In patients without CKD, however, the addition of fenofibrate was associated with a significant 36% reduction of CV mortality (hazards ratio [HR] 0.64; 95% CI 0.42-0.97; p value for treatment interaction <0.05) and 44% lower rate of fatal or non-fatal congestive heart failure (CHF; HR 0.56; 95% CI 0.37-0.84; p value treatment interaction <0.03).

CONCLUSIONS

For patients with type 2 diabetes at high CV risk but no CKD, fenofibrate therapy added to statin reduced the CV mortality and the rate of fatal and non-fatal CHF.

Adherence with renal dosing recommendations in outpatients undergoing haemodialysis

WHAT IS KNOWN AND OBJECTIVE

Adjustment of drug dosage in patients with end-stage renal disease prevents serious adverse effects, which occur due to the accumulation of drugs or other toxic metabolites. Nevertheless, dosing errors occur most commonly among patients with end-stage renal disease. The aim of this study was to assess the quality of care for end-stage renal disease outpatients using their renal dosing adjustment status.

METHODS

A cross-sectional study was performed using the data collected from 43 South Korean medical institutions via questionnaires. A total of 2428 patients on haemodialysis, who were at least 18 years of age, were included. Among these patients, the study population was confined to patients who were taking medications and required renal dosing adjustments from three therapeutic classes: antihypertensives, antihyperglycaemics and lipid-modifying agents. The study population (n = 828) was prescribed a total of 1097 drug orders for the target drugs. Determination of appropriate dosage adjustment was based on GFR (glomerular filtration rate) using the Modification of Diet in Renal Disease revised 4-variable equation. The primary outcome was non-adherence to drug dosing requirements for end-stage renal disease patients with consideration to their renal function.

RESULTS AND DISCUSSION

Among the study population (n = 828), 469 haemodialysis patients were identified as having drug orders that were adherent to renal dosing recommendations. There were significant differences between the patient groups who received recommendation-adherent and non-adherent drug orders in the characteristics of the medical institutions they visited, causes of chronic renal failure and prevalence of concurrent diabetes mellitus. The primary factor of non-adherence to renal dosing adjustment recommendations was characteristics of medical institutions. Compared to tertiary hospitals, secondary hospitals and primary care clinics were 1·16 and 1·22 times, respectively, more non-adherent in accordance with the multivariate analysis (OR: 1.16, 95% CI: 1.02-1.20, OR: 1.22, 95% CI: 1·00-1·36, respectively).

WHAT IS NEW AND CONCLUSIONS

Dosing error is one of the most common problems among patients with renal failure. To decrease the dosing errors, an improvement needs to be made in medical institutions. This can be accomplished by implementing the clinical decision support systems that educate physicians on appropriate renal dosing and help them prescribe appropriate drug dosages.

Effect of Kidney Function on Drug Kinetics and Dosing in Neonates, Infants, and Children

Neonates, infants, and children differ from adults in many aspects, not just in age, weight, and body composition. Growth, maturation and environmental factors affect drug kinetics, response and dosing in pediatric patients. Almost 80% of drugs have not been studied in children, and dosing of these drugs is derived from adult doses by adjusting for body weight/size. As developmental and maturational changes are complex processes, such simplified methods may result in subtherapeutic effects or adverse events. Kidney function is impaired during the first 2 years of life as a result of normal growth and development. Reduced kidney function during childhood has an impact not only on renal clearance but also on absorption, distribution, metabolism and nonrenal clearance of drugs. 'Omics'-based technologies, such as proteomics and metabolomics, can be leveraged to uncover novel markers for kidney function during normal development, acute kidney injury, and chronic diseases. Pharmacometric modeling and simulation can be applied to simplify the design of pediatric investigations, characterize the effects of kidney function on drug exposure and response, and fine-tune dosing in pediatric patients, especially in those with impaired kidney function. One case study of amikacin dosing in neonates with reduced kidney function is presented. Collaborative efforts between clinicians and scientists in academia, industry, and regulatory agencies are required to evaluate new renal biomarkers, collect and share prospective pharmacokinetic, genetic and clinical data, build integrated pharmacometric models for key drugs, optimize and standardize dosing strategies, develop bedside decision tools, and enhance labels of drugs utilized in neonates, infants, and children.

Use of renal risk drugs in patients with renal impairment

BACKGROUND

Renal impairment often goes unrecognised until the most advanced stages. Patients with renal impairment use a variety of drugs and the pharmacokinetics and drug effects are prone to change.

OBJECTIVE

Describe drug related problems in a population of patients with renal impairment, investigate possible risk factors, and investigate whether the clinical pharmacist can propose relevant measures to solve the problems.

SETTING

The internal medicine department at Innlandet Hospital Trust Gjøvik, Norway.

METHOD

A prospective study enrolling patients (≥18 years) with moderate and severe renal impairment, i.e. with glomerular filtration rate of 30-59 and 15-29 ml/min/1.73 m(2), respectively, and using at least one drug. The clinical pharmacist reviewed the patients' drug regimen with focus on drug related problems, related to renal function. Problems identified were discussed with the multidisciplinary team, or directly with the physician.

MAIN OUTCOME MEASURE

The number of drug related problems.

RESULTS

The results are based on data from 79 patients, 21 with severe and 58 with moderate renal impairment. Most patients, 92.4 %, used 5 or more drugs; in average 10.2 (range 2-27). In total, 88 drug related problems were identified in 49 patients, i.e. in 62 %. The most frequently occurring problems were incorrect dose (45.5 %) and inappropriate drug (41.0 %). There was a significant correlation between both the degree of renal impairment and the number of drugs, and the number of drug related problems. The acceptance rate of the clinical pharmacist's interventions was 95.7 %. The drugs most frequently associated with drug related problems were metformin, benzylpenicillin and furosemide.

CONCLUSION

Drug related problems often occur in patients with renal impairment. Incorrect drug dose and inappropriate drug choice according to the patients' renal function were the most common problems. Patients with the most complex drug treatment, i.e. with increasing degree of renal impairment and increasing number of drugs, are at greater risk of drug related problems. The high acceptance rate for the pharmacist's interventions supports the inclusion of a clinical pharmacist in the multidisciplinary treatment team to increase awareness and optimisation of the drug treatment in this patient group.

A Synopsis of Clinical Pharmacokinetic Alterations in Advanced CKD

Unrecognized alterations in pharmacokinetics, which quantitatively describes the time course of drug disposition in the body, may lead to clinically significant changes in systemic exposure and corresponding response to drugs in patients with chronic kidney disease (CKD). Clinicians must take pharmacokinetic changes into consideration when selecting and dosing medications in CKD patients to optimize the risk:benefit ratio. Pharmacokinetic changes in absorption, distribution, and renal clearance are well characterized and generally predictable for most drugs. Conversely, changes in nonrenal clearance are less well understood and corresponding clinical implications are still being elucidated. This review provides a synopsis of alterations in each of these pharmacokinetic parameters observed in patients with advanced CKD.

Chronic kidney disease and intensive glycemic control increase cardiovascular risk in patients with type 2 diabetes

Results of the main Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial indicate that intensive glucose lowering increases cardiovascular and all-cause mortality. As the contribution of mild-to-moderate chronic kidney disease (CKD) to these risks is not known, we assessed the impact on cardiovascular outcomes in this population. Renal function data were available on 10,136 patients of the original ACCORD cohort. Of those, 6,506 were free of CKD at baseline and 3,636 met the criteria for CKD. Participants were randomly assigned to a treatment strategy of either intensive or standard glycemic goal. The primary outcome, all-cause and cardiovascular mortality, and prespecified secondary outcomes were evaluated. Risk for the primary outcome was 87% higher in patients with than in those without CKD (hazard ratio of 1.866; 95% CI: 1.651-2.110). All prespecified secondary outcomes were 1.5 to 3 times more frequent in patients with than in those without CKD. In patients with CKD, compared with standard therapy, intensive glucose lowering was significantly associated with both 31% higher all-cause mortality (1.306: 1.065-1.600) and 41% higher cardiovascular mortality (1.412: 1.052-1.892). No significant effects were found in patients without CKD. Thus, in high-risk patients with type II diabetes, mild and moderate CKD is associated with increased cardiovascular risk. Intensive glycemic control significantly increases the risk of cardiovascular and all-cause mortality in this population.

Medication pitfalls in the CKD clinic: case presentations

The kidney plays a major role in pharmacokinetics and pharmacodynamics of drugs; therefore, medication errors can result from failure to properly adjust medications in patients with CKD. It is the responsibility of all health-care providers to work collectively when reviewing medications, initiating new medications, and adjusting doses of current medications. Awareness of appropriate dosing recommendations can significantly decrease medication error-associated morbidity, mortality, and cost.

Pharmacokinetic considerations in chronic kidney disease and patients requiring dialysis

INTRODUCTION

Chronic kidney disease (CKD) is the progressive decline in renal function over time. Patients with end-stage renal disease require renal replacement therapy such as hemodialysis to support life. Hemodialysis patients require several medications to treat a variety of comorbid conditions. Polypharmacy accompanied by alterations in the pharmacokinetics of medications places hemodialysis patients at increased risk of drug accumulation and adverse events.

AREAS COVERED

We review alterations in the pharmacokinetics of drugs in hemodialysis patients. The major areas of pharmacokinetics, absorption, distribution, metabolism and excretion, are covered and, where appropriate, differences between dialysis patients and non-dialysis CKD patients are compared. In addition, we review the importance of drug dialyzability and its potential impact on drug efficacy. Finally, we describe important clinical examples demonstrating nonrenal drug clearance is significantly altered in CKD.

EXPERT OPINION

Decreases in renal drug excretion experienced by hemodialysis patients have been known for years. Recent animal and human clinical pharmacokinetic studies have highlighted that nonrenal clearance of drugs is also substantially decreased in CKD. Clinical pharmacokinetic studies are required to determine the optimal dosage of drugs in CKD and hemodialysis patients in order to decrease the incidence of adverse medication events in these patient populations.

Treating epilepsy in the setting of medical comorbidities

OPINION STATEMENT

Treatment of epilepsy in patients with medical comorbidities can be challenging. Comorbidities can affect medical management and quality of life. In this review, we discuss treatment options in patients with epilepsy and medical comorbidities. In our opinion, the best way to manage patients with medical comorbidities and epilepsy is to accurately recognize and diagnose medical comorbidities, and to have adequate knowledge and familiarity with antiepileptic drug (AED) metabolism, dosing, side effects, and drug interactions. We believe the trend should move toward using the newer generation of AEDs given their generally reduced rate of adverse effects and interactions. The primary goal of therapy is seizure freedom without side effects.

Medication dosing in patients with chronic kidney disease

Appropriate dosage adjustments for patients with chronic kidney disease (CKD) are critical for patient safety. This article reviews adjustments for common antidiabetic, antibiotic, analgesic, and antithrombotic medications, as well as important patient teaching information for over-the-counter (OTC) medications.

Medication-prescribing patterns of primary care physicians in chronic kidney disease

BACKGROUND

We investigated the medication-prescribing patterns of primary care physicians in chronic kidney disease (CKD).

SUBJECTS AND METHODS

This cross-sectional study included 3,310 medical doctors who graduated from Jichi Medical University. The study instrument was a self-administered questionnaire to investigate their age group, specialty, workplace, existence of a dialysis center at workplace, and their prescription frequencies (high, moderate, low, very low) of the following agents--calcium (Ca) inhibitors, angiotensin-converting enzyme inhibitors (ACEIs), angiotensin II receptor antagonist (ARBs), statins, anti-platelet agents, erythropoietin (Epo), AST-120, vitamin D, and sodium hydrogen carbonate (NaHCO(3)).

RESULTS

From a total of 933 responses, 547 (61.0 %) medical doctors prescribed medication for CKD. The prescription frequencies of Ca inhibitors, ACEIs, and ARBs were high (>90 %, high + moderate), those of statins, anti-platelet agents, Epo, and AST-120 were moderate (90-50 %, high + moderate), and those of vitamin D and NaHCO(3) were low (<50 %, high + moderate). The primary care physician's specialty was significantly associated with their prescription frequency of Ca inhibitors (p < 0.01). Their workplace was significantly associated with their prescription frequency of ACEIs (p < 0.01), ARBs (p < 0.01), Epo (p < 0.01) and vitamin D (p < 0.01). The existence of a dialysis center at their workplace was significantly associated with their prescription frequency of Epo (p < 0.01), vitamin D (p < 0.01) and NaHCO(3) (p < 0.01). Their age was not associated with their prescription frequency of any agents.

CONCLUSION

Antihypertensives were highly prescribed, and vitamin D and NaHCO(3) were less prescribed by primary care physicians for CKD. There were certain associations between the prescribing patterns of primary care physicians for CKD and their specialty, workplace and the existence of a dialysis center at their workplace.

Impact of vendor computerized physician order entry on patients with renal impairment in community hospitals

BACKGROUND

Adverse drug events (ADEs) are common among hospitalized patients with renal impairment.

OBJECTIVE

To determine whether computerized physician order entry (CPOE) systems with clinical decision support capabilities reduce the frequency of renally related ADEs in hospitals.

DESIGN, SETTING, AND PATIENTS

Quasi-experimental study of 1590 adult patients with renal impairment who were admitted to 5 community hospitals in Massachusetts from January 2005 to September 2010, preimplementation and postimplementation of CPOE.

INTERVENTION

Varying levels of clinical decision support, ranging from basic CPOE only (sites 4 and 5), rudimentary clinical decision support (sites 1 and 2), and advanced clinical decision support (site 3).

MEASUREMENTS

Primary outcome was the rate of preventable ADEs from nephrotoxic and/or renally cleared medications. Similarly, secondary outcomes were the rates of overall ADEs and potential ADEs.

KEY RESULTS

There was a 45% decrease in the rate of preventable ADEs following implementation (8.0/100 vs 4.4/100 admissions; P < 0.01), and the impact was related to the level of decision support. Basic CPOE was not associated with any significant benefit (4.6/100 vs 4.3/100 admissions; P = 0.87). There was a nonsignificant decrease in preventable ADEs with rudimentary clinical decision support (9.1/100 vs 6.4/100 admissions; P = 0.22). However, substantial reduction was seen with advanced clinical decision support (12.4/100 vs 0/100 admissions; P = 0.01). Despite these benefits, a significant increase in potential ADEs was found for all systems (55.5/100 vs 136.8/100 admissions; P < 0.01).

CONCLUSION

Vendor-developed CPOE with advanced clinical decision support can reduce the occurrence of preventable ADEs but may be associated with an increase in potential ADEs.

Estimating renal function to reduce the risk of adverse drug reactions

The aging process is characterized by relevant changes in pharmacokinetics. Renal function is known to decline with aging. However, as a result of reduced muscle mass, older individuals frequently have a depressed glomerular filtration rate (GFR) despite normal serum creatinine, and such a concealed renal insufficiency may impact significantly on the clearance of hydrosoluble drugs, as well as the risk of adverse drug reactions (ADRs) from hydrosoluble drugs. The assessment of renal function should thus be a mandatory item in the global examination of patient characteristics. Equations for estimating GFR have become very popular in recent years. However, different equations may yield significantly different estimated glomerular filtration rate (eGFR) values, which have important implications in dosing drugs cleared by the kidney. Current knowledge suggests that eGFR based on the Chronic Kidney Disease-Epidemiological Collaboration (CKD-EPI) study equation outperformed eGFR based on the Modification of Diet in Renal Disease (MDRD) study equation and creatinine clearance estimate based on the Cockcroft-Gault formula as a predictor of ADRs from kidney cleared drugs. More recently, the combined creatinine-cystatin C equation was shown to perform better than equations based on either of these markers alone in diagnosing CKD, even in older patients. However, its accuracy in predicting ADRs and usefulness in drug dosing is still to be investigated.

Pharmacokinetics of aliskiren in patients with end-stage renal disease undergoing haemodialysis

BACKGROUND AND OBJECTIVES

Aliskiren represents a novel class of orally active renin inhibitors. This study analyses the pharmacokinetics, tolerability and safety of single-dose aliskiren inpatients with end-stage renal disease (ESRD) undergoing haemodialysis.

METHODS

Six ESRD patients and six matched healthy volunteers were enrolled in an open-label, parallel-group, single-sequence study. The ESRD patients underwent two treatment periods where 300 mg of aliskiren was administered 48 or 1 h before a standardized haemodialysis session (4 h, 1.4 m(2) high-flux filter, blood flow 300 mL/min, dialysate flow 500 mL/min). Washout was >10 days between both periods. Blood and dialysis samples were taken for up to 96 h postdose to determine aliskiren concentrations.

RESULTS

Compared with the healthy subjects (1681 ± 1034 ng·h/mL), the area under the plasma concentration-time curve (AUC) from time zero to infinity was 61% (haemodialysis at 48 h) and 41% (haemodialysis at 1 h) higher in ESRD patients receiving single-dose aliskiren 300 mg. The maximum (peak) plasma drug concentration (481 ± 497 ng/mL in healthy subjects) was 17% higher (haemodialysis at 48 h) and 16% lower (haemodialysis at 1 h). In both treatment periods, dialysis clearance was below 2% of oral clearance and the mean fraction eliminated from circulation was 10 and 12% in period 1 and 2, respectively. Drug AUCs were similar in ESRD patients receiving aliskiren 1 or 48 h before dialysis. No severe adverse events occurred.

CONCLUSION

The exposure of aliskiren is moderately higher in ESRD patients. Only a minor portion is removed by a typical haemodialysis session. Aliskiren exposure is not significantly affected by intermittent haemodialysis, suggesting that no dose adjustment is necessary in this population.

Evaluation of potential interactions between mycophenolic acid derivatives and proton pump inhibitors

OBJECTIVE

To evaluate the incidence of gastrointestinal (GI) complications in solid organ transplant (SOT) recipients, impact of the complications on transplant outcomes, and the potential interactions between mycophenolic acid (MPA) derivatives and proton pump inhibitors (PPIs).

DATA SOURCES

An unrestricted literature search (1980-January 2012) was performed with MEDLINE and EMBASE using the following key words: drug-drug interaction, enteric-coated mycophenolic acid, GI complications, mycophenolate mofetil, solid organ transplant, and proton pump inhibitor, including individual agents within the class. Abstracts from scientific meetings were also evaluated. Additionally, reference citations from identified publications were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Relevant English-language, original research articles and review articles were evaluated if they focused on any of the topics identified in the search or included substantial content addressing GI complications in SOT recipients or drug interactions.

DATA SYNTHESIS

GI complications are frequent among SOT recipients, with some studies showing prevalence rates as high as 70%. Transplant outcomes among renal transplant recipients are significantly impacted by GI complications, especially in patients requiring immunosuppressant dosage reductions or premature discontinuation. To this end, PPI use among patients receiving transplants is common. Recent data demonstrate that PPIs significantly reduce the overall exposure to MPA after oral administration of mycophenolate mofetil. Similar studies show this interaction does not exist between PPIs and enteric-coated mycophenolic acid (EC-MPA). Unfortunately, most of the available data evaluating this interaction are pharmacokinetic analyses that do not investigate the clinical impact of this interaction.

CONCLUSIONS

A significant interaction exists between PPIs and mycophenolate mofetil secondary to reduced dissolution of mycophenolate mofetil in higher pH environments. EC-MPA is not absorbed in the stomach; therefore, low intragastric acidity does not impact EC-MPA and bioavailability is maintained with this formulation during PPI coadministration. The clinical impact of this interaction is unknown, yet one can theorize that reduced exposure to MPA in SOT recipients can increase the risk of allograft rejection and/or failure.

Current understanding of drug disposition in kidney disease

Patients with chronic kidney disease (CKD) represent 13% of the American population. CKD has been shown to significantly alter drug disposition of nonrenally eliminated drugs. Indeed, modifications in the expression and function of intestinal and hepatic drug metabolism enzymes and uptake and efflux transporters have been reported. Uremic toxins, inflammatory cytokines, and parathyroid hormone have been implicated as causes. These changes can have an important clinical impact on drug disposition and lead to unintended toxicity if they are administered without dose adjustment in patients with impaired kidney function. This review summarizes recent preclinical and clinical studies and presents the current understanding of the effect of CKD on drug absorption, distribution, metabolism, and excretion.

Population pharmacokinetics of telapristone (CDB-4124) and its active monodemethylated metabolite CDB-4453, with a mixture model for total clearance

Telapristone is a selective progesterone antagonist that is being developed for the long-term treatment of symptoms associated with endometriosis and uterine fibroids. The population pharmacokinetics of telapristone (CDB-4124) and CDB-4453 was investigated using nonlinear mixed-effects modeling. Data from two clinical studies (n = 32) were included in the analysis. A two-compartment (parent) one compartment (metabolite) mixture model (with two populations for apparent clearance) with first-order absorption and elimination adequately described the pharmacokinetics of telapristone and CDB-4453. Telapristone was rapidly absorbed with an absorption rate constant (Ka) of 1.26 h⁻¹. Moderate renal impairment resulted in a 74% decrease in Ka. The population estimates for oral clearance (CL/F) for the two populations were 11.6 and 3.34 L/h, respectively, with 25% of the subjects being allocated to the high-clearance group. Apparent volume of distribution for the central compartment (V2/F) was 37.4 L, apparent inter-compartmental clearance (Q/F) was 21.9 L/h, and apparent peripheral volume of distribution for the parent (V4/F) was 120 L. The ratio of the fraction of telapristone converted to CDB-4453 to the distribution volume of CDB-4453 (Fmet_est) was 0.20/L. Apparent volume of distribution of the metabolite compartment (V3/F) was fixed to 1 L and apparent clearance of the metabolite (CLM/F) was 2.43 L/h. A two-compartment parent-metabolite model adequately described the pharmacokinetics of telapristone and CDB-4453. The clearance of telapristone was separated into two populations and could be the result of metabolism via polymorphic CYP3A5.

Drug dosing consideration in patients with acute and chronic kidney disease-a clinical update from Kidney Disease: Improving Global Outcomes (KDIGO)

Drug dosage adjustment for patients with acute or chronic kidney disease is an accepted standard of practice. The challenge is how to accurately estimate a patient's kidney function in both acute and chronic kidney disease and determine the influence of renal replacement therapies on drug disposition. Kidney Disease: Improving Global Outcomes (KDIGO) held a conference to investigate these issues and propose recommendations for practitioners, researchers, and those involved in the drug development and regulatory arenas. The conference attendees discussed the major challenges facing drug dosage adjustment for patients with kidney disease. In particular, although glomerular filtration rate is the metric used to guide dose adjustment, kidney disease does affect nonrenal clearances, and this is not adequately considered in most pharmacokinetic studies. There are also inadequate studies in patients receiving all forms of renal replacement therapy and in the pediatric population. The conference generated 37 recommendations for clinical practice, 32 recommendations for future research directions, and 24 recommendations for regulatory agencies (US Food and Drug Administration and European Medicines Agency) to enhance the quality of pharmacokinetic and pharmacodynamic information available to clinicians. The KDIGO Conference highlighted the gaps and focused on crafting paths to the future that will stimulate research and improve the global outcomes of patients with acute and chronic kidney disease.

Recommendations for the proper use of nonprescription cough suppressants and expectorants in solid-organ transplant recipients

OBJECTIVE

To describe the pharmacology and safety of oral over-the-counter cough suppressants and expectorants and to present recommendations for the use of these agents in solid-organ transplant recipients based on the potential for adverse drug reactions or drug-disease interactions.

DATA SOURCES AND EXTRACTION

Data from journal articles and other sources describing the pharmacology and safety of over-the-counter cough suppressants and expectorants, drug-drug interactions with immunosuppressive agents, and drug-disease state interactions are reviewed.

DATA SYNTHESIS

Potential and documented drug-drug interactions between immunosuppressive agents and over-the-counter cough medications guaifenesin, dextromethorphan, diphenhydramine, and codeine were evaluated on the basis of pharmacokinetic and pharmacodynamic principles. Interactions between these cough medications and the physiological changes in the body following transplantation also were examined.

CONCLUSION

Diphenhydramine requires additional monitoring when used to treat cough in transplant recipients owing to its anticholinergic properties and the potential for interactions with cyclosporine. Dextromethorphan can be used in most transplant recipients, although greater caution should be exercised if the patient has undergone liver transplant or has liver impairment. Guaifenesin can be used in transplant recipients but should be used with caution in patients receiving kidney or lung transplants and in patients with renal impairment. Codeine combined with guaifenesin is another option for cough and can be used in most transplant patients although those with reduced renal function should be monitored carefully for adverse events.

Recommendations for the Proper Use of Nonprescription Cough Suppressants and Expectorants in Solid-Organ Transplant Recipients

Objective

To describe the pharmacology and safety of oral over-the-counter cough suppressants and expectorants and to present recommendations for the use of these agents in solid-organ transplant recipients based on the potential for adverse drug reactions or drug-disease interactions.

Data Sources and Extraction

Data from journal articles and other sources describing the pharmacology and safety of over-the-counter cough suppressants and expectorants, drug-drug interactions with immunosuppressive agents, and drug-disease state interactions are reviewed.

Data Synthesis

Potential and documented drug-drug interactions between immunosuppressive agents and over-the-counter cough medications guaifenesin, dextromethorphan, diphenhydramine, and codeine were evaluated on the basis of pharmacokinetic and pharmacodynamic principles. Interactions between these cough medications and the physiological changes in the body following transplantation also were examined.

Conclusion

Diphenhydramine requires additional monitoring when used to treat cough in transplant recipients owing to its anticholinergic properties and the potential for interactions with cyclosporine. Dextromethorphan can be used in most transplant recipients, although greater caution should be exercised if the patient has undergone liver transplant or has liver impairment. Guaifenesin can be used in transplant recipients but should be used with caution in patients receiving kidney or lung transplants and in patients with renal impairment. Codeine combined with guaifenesin is another option for cough and can be used in most transplant patients although those with reduced renal function should be monitored carefully for adverse events.

Antibiotic pharmacokinetic and pharmacodynamic considerations in patients with kidney disease

Although pharmacokinetic changes occurring in kidney disease are well described, pharmacodynamics in kidney disease is rarely considered. Knowledge of pharmacodynamic principles can allow a clinician to maximize an antibiotic's effectiveness while minimizing adverse effects and antibacterial resistance. An antibiotic's pharmacokinetic and pharmacodynamic profiles should drive dose adjustment decisions in patients with kidney disease. For example, although the half-lives of beta-lactams and aminoglycosides are both prolonged in these patients, beta-lactams exhibit time-dependent antibacterial activity; consequently, maintenance doses should be smaller but given at the same interval. In contrast, aminoglycosides are concentration-dependent antibiotics; hence prolongation of the dosing interval while using larger doses may be advantageous. The timing of drug administration in relation to hemodialysis may be used to achieve specific pharmacodynamic goals. Aminoglycosides given before hemodialysis generate high peaks, whereas subsequent dialytic drug removal minimizes the area under the serum concentration-time curve, potentially decreasing the risk of developing toxicity. Furthermore, new dialysis prescribing patterns (eg, automated peritoneal dialysis, nocturnal dialysis) affect pharmacokinetic and pharmacodynamic parameters in ways not appreciated by clinicians. Studies quantifying the often considerable drug removal with these therapies, as well as efforts to identify pharmacodynamic targets in patients with kidney disease are essential. This paper reviews pharmacodynamic as well as pharmacokinetic issues that should be considered when prescribing antibiotics to treat infections in this population.

Psychiatric issues in solid organ transplantation

The identification and treatment of psychiatric comorbidity in patients undergoing solid organ transplantation present a unique opportunity for psychiatric involvement in the care of medically complex patients. The burden of psychiatric illness in patients awaiting transplant and following transplant is significant and associated with potential morbidity and mortality. Possibilities for psychiatric liaison with our colleagues in transplant medicine and surgery start with the comprehensive psychiatric evaluation that is often performed with potential organ recipients and donors. The vital role of the psychiatrist continues following transplantation, as adjustment is often a stressful experience with associated psychiatric comorbidity. The treatment of psychiatric illness in patients following transplantation requires an understanding of the immunosuppressant medications that patients may be taking, coupled with an awareness of the associated risks of adverse effects and drug-drug interactions.

Drug Use and Dosing in Chronic Kidney Disease

One of the most important drug-related problems in patients with chronic kidney disease (CKD) is medication dosing errors. Many medications and their metabolites are eliminated through the kidney. Thus, adequate renal function is important to avoid toxicity. Patients with renal impairment often have alterations in their pharmacokinetic and pharmacodynamic pa-rameters. The clearance of drugs eliminated primarily by renal filtration is decreased by renal disease. Therefore, special consideration should be taken when these drugs are prescribed to patients with impaired renal function. Despite the importance of dosage adjustment in patients with CKD, such adjustments are sometimes ignored. Physicians and pharmacists can work together to accomplish safe drug prescribing. This task can be complex and require a stepwise approach to ensure effectiveness, minimise further damage and prevent drug nephrotoxicity. Key words: Dosage adjustment, Renal impairment, Stepwise approach

Impact of a Renal Drug Dosing Service on Dose Adjustment in Hospitalized Patients with Chronic Kidney Disease

Background:

Appropriate drug selection and dosing for patients with chronic kidney disease (CKD) is important to avoid unwanted drug effects and ensure optimal patient outcomes.

Objective:

To assess the rate of inappropriate dosing in patients with CKD in a nephrology unit and to evaluate the impact on dose adjustment, adverse drug events (ADEs), and drug cost of having a pharmacist accompany a team of physicians on their rounds.

Methods:

This was a comparative study with a preintervention and postintervention design. The preintervention phase served as the control; it was prospective and observational only and was conducted from the beginning of February to the end of May 2007. The second phase (intervention phase) was conducted from the beginning of March to the end of June 2008. Two random samples of 300 patients with an estimated creatinine clearance less than or equal to 50 mL/min were included. During the intervention phase, a clinical pharmacist made rounds with the nephrology unit team and gave dosing adjustment recommendations when needed. A collection of reliable and up-to-date drug information references that are commonly used globally were used during the intervention.

Results:

In the preintervention group, drug dosage adjustment or avoidance, based on renal function, was necessary in 607 of 2814 (21.6%) prescriptions. Of these, 322 (53.0%) did not comply with guidelines. In the intervention group, adjustment was necessary for 640 of 2981 (21.5%) prescriptions. The pharmacist made 388 recommendations related to dosing adjustment, 212 (54.6%) of which were accepted by physicians. Clinicians' noncompliance with dosing guidelines decreased to 176 (27.5%) (p < 0.001). In the preintervention group, 64 (21.3%) patients had a suspected ADE, with a total of 73 events. In the intervention group, this number was significantly lower with 49 events in 48 (16.0%) patients (p < 0.05). The intervention resulted in drug cost savings of $2250 US.

Conclusions:

A renal drug dosing service for patients hospitalized with CKD can increase the proportion of drug dosing that is adjusted to take into account renal function. This can save drug costs and may prevent ADEs.

Strategies for reducing polypharmacy and other medication-related problems in chronic kidney disease

Medication-related problems are very common in patients with chronic kidney disease (CKD). These problems are often avoidable and can result in detrimental patient consequences and high financial costs. Despite these risks, it is often medically necessary to prescribe multiple medications to treat the comorbid conditions that accompany CKD. In addition, patients' use of nonprescription medications and changes in pharmacokinetic and pharmacodynamic parameters may further contribute to medication-related problems in CKD, including drug interactions and the need for dosage adjustments. A structured medication assessment process is one approach to reducing the risks associated with medication-related problems. This multifaceted process involves a comprehensive medication history interview, structured therapy assessment, and open communication between members of the medical team. A detailed description of this process is provided to aid healthcare providers in addressing this important issue.

Treating seizures in renal and hepatic failure

INTRODUCTION: Renal and hepatic diseases cause seizures and patients with epilepsy may suffer from such diseases which change antiepileptic drugs (AEDs) metabolism. OBJECTIVES: To revise how seizures may be caused by metabolic disturbances due to renal or hepatic diseases, by their treatment or by comorbidities and how AEDs choice might be influenced by these conditions. RESULTS: Seizures arise in renal failure due to toxins accumulation and to complications like sepsis, hemorrhage, malignant hypertension, pH and hydroelectrolytic disturbances. Hemodialysis leads to acute dysequilibrium syndrome and to dementia. Peritoneal dialysis may cause hyperosmolar non-ketotic coma. Post-renal transplant immunosupression is neurotoxic and cause posterior leukoencephalopathy, cerebral lymphoma and infections. Some antibiotics decrease convulsive thresholds, risking status epilepticus. Most commonly used AEDs in uremia are benzodiazepines, ethosuximide, phenytoin and phenobarbital. When treating epilepsy in renal failure, the choice of AED remains linked to seizure type, but doses should be adjusted especially in the case of hydrosoluble, low-molecular-weight, low-protein-bound, low apparent distribution volume AEDs. Hepatic failure leads to encephalopathy and seizures treated by ammonium levels and intestinal bacterial activity reductions, reversal of cerebral edema and intracranial hypertension. Phenytoin and benzodiazepines are usually ineffective. Seizures caused by post-hepatic immunosupression can be treated by phenytoin or levetiracetam. Seizures in Wilson's disease may result from D-penicillamine dependent piridoxine deficiency. Porphyria seizures may be treated with gabapentin, oxcarbazepine and levetiracetam. Hepatic disease changes AEDs pharmacokinetics and needs doses readjustments. Little liver-metabolized AEDs as gabapentin, oxcarbazepine and levetiracetam are theoretically more adequate. CONCLUSIONS: Efficient seizures treatment in renal and hepatic diseases requires adequate diagnosis of these disturbances and their comorbidities besides good knowledge on AEDs metabolism, their pharmacokinetic changes in such diseases, careful use of concomitant medications and AEDs serum levels monitoring.

Medications in the kidney

Patients with chronic kidney disease (CKD) constitute a population at high risk for adverse drug reactions and/or drug-drug interactions. Renal dysfunction-induced pathophysiological changes may alter both medication pharmacodynamics and handling. Most pharmacokinetic parameters are adversely affected by impaired kidney function, among which reduced glomerular filtration and altered tubular secretion and reabsorption lead to the most specific alterations. Dosages of drugs cleared by the kidney should usually be adjusted according to creatinine clearance. Recommended methods for maintenance dosing adjustments are dose reductions, lengthening the dosing interval, or both. Appropriate drug selection and dosing in patients with CKD is imperative to avoid drug adverse events and to ensure optimal patient outcomes.

Pharmacokinetics of the oral direct renin inhibitor aliskiren alone and in combination with irbesartan in renal impairment

BACKGROUND

Aliskiren is an orally active direct renin inhibitor approved for the treatment of hypertension. This study assessed the effects of renal impairment on the pharmacokinetics and safety of aliskiren alone and in combination with the angiotensin receptor antagonist irbesartan.

METHODS

This open-label study enrolled 17 males with mild, moderate or severe renal impairment (creatinine clearance [CL(CR)] 50-80, 30-49 and <30 mL/minute, respectively) and 17 healthy males matched for age and bodyweight. Subjects received oral aliskiren 300 mg once daily on days 1-7 and aliskiren coadministered with irbesartan 300 mg on days 8-14. Plasma aliskiren concentrations were determined by high-performance liquid chromatography/tandem mass spectrometry at frequent intervals up to 24 hours after dosing on days 1, 7 and 14.

RESULTS

Renal clearance of aliskiren averaged 1280 +/- 500 mL/hour (mean +/- SD) in healthy subjects and 559 +/- 220, 312 +/- 75 and 243 +/- 186 mL/hour in patients with mild, moderate and severe renal impairment, respectively. At steady state (day 7), the geometric mean ratios (renal impairment : matched healthy volunteers) ranged from 1.21 to 2.05 for the area under the plasma concentration-time curve (AUC) over the dosage interval tau (24h) [AUC(tau)]) and from 0.83 to 2.25 for the maximum observed plasma concentration of aliskiren at steady state. Changes in exposure did not correlate with CL(CR), consistent with an effect of renal impairment on non-renal drug disposition. The observed large intersubject variability in aliskiren pharmacokinetic parameters was unrelated to the degree of renal impairment. Accumulation of aliskiren at steady state (indicated by the AUC from 0 and 24 hours [AUC(24)] on day 7 vs day 1) was similar in healthy subjects (1.79 [95% CI 1.24, 2.60]) and those with renal impairment (range 1.39-1.99). Coadministration with irbesartan did not alter the pharmacokinetics of aliskiren. Aliskiren was well tolerated when administered alone or with irbesartan.

CONCLUSIONS

Exposure to aliskiren is increased by renal impairment but does not correlate with the severity of renal impairment (CL(CR)). This is consistent with previous data indicating that renal clearance of aliskiren represents only a small fraction of total clearance. Initial dose adjustment of aliskiren is unlikely to be required in patients with renal impairment.

Use of newer anticoagulants in patients with chronic kidney disease

PURPOSE

The current indications, dosing, and practical considerations for use of newer anticoagulants in patients with various degrees of renal impairment who do not require dialysis are reviewed.

SUMMARY

Kidney function should generally be evaluated in all patients commencing anticoagulant therapy. As in the general population, hospitalized patients with impaired renal function most often have impairment that is mild to moderate in severity. Drug dosing in patients with chronic kidney disease may require that adjustment be made to the usual loading or maintenance dose of a drug. Newer anticoagulants with labeling approved by the Food and Drug Administration for venous thromboembolism (VTE) prophylaxis, treatment, or both include the low-molecular-weight heparins (LMWHs) and the factor Xa inhibitor fondaparinux. Some LMWHs are also indicated for the management of patients with acute coronary syndrome (ACS). All of the newer anticoagulants currently available for the management of VTE and ACS have approved labeling for use in patients with mild-to-moderate renal impairment. Currently available LMWHs, factor Xa inhibitors, and direct thrombin inhibitors (excluding argatroban) are eliminated primarily by the kidneys, so dosing in patients with severe renal impairment may require cautious dosage reduction or increased monitoring for bleeding and thromboembolic complications or both. Unfractionated heparin is the preferred anticoagulant for use in most of these patients.

CONCLUSION

Newer anticoagulants should be used with caution in patients with mild-to-moderate renal impairment. Unfractionated heparin remains the preferred anticoagulant in most patients with severe renal impairment even though its use is associated with increased bleeding in this population. Dosing of newer anticoagulants, except argatroban, requires cautious dosage reduction and increased monitoring for complications.

Selected pharmacokinetic issues in patients with chronic kidney disease

Pharmacotherapy plays an important role in the care of a chronic kidney disease (CKD) patient but delivering this therapy can be challenging. Besides alterations in the pharmacokinetic parameters of absorption, distribution, metabolism and elimination, the average CKD patient must take multiple medications each day. The likelihood of an adverse drug reaction increases with each medication added to these patients' daily regimen. In this article we discuss selected pharmacokinetic issues unique to CKD patients.