Effects of lanthanum carbonate on the absorption and oral bioavailability of ciprofloxacin

A critical review of Roxadustat formulations, solid state studies, and analytical methodology

This review aims to collate information about the analytical methodologies, bioanalytical methodologies, pharmaceutical formulations, solid-state studies, and the current and future market scenario for a relatively new class of drugs, Roxadustat. Roxadustat is a hypoxia-inducible factor propyl hydroxylase inhibitor that significantly increases blood hemoglobin via the action of transcriptional activator HIF. As the molecule has a promising role in stimulating erythropoiesis, it is considered an ideal therapeutic agent for patients with anemia. In the current review, an attempt has been made to compile the pharmacological, pharmacokinetic, and pharmacodynamic characteristics of Roxadustat and systematically present product development data. This drug has several polymorphs of cocrystal, co-former, and salt, which have been explained in detail in the current work. The comprehensive review summarizes all the chromatographic methods and is presented in table form. This review has extensively covered Liquid chromatography-tandem mass spectrometry methods used to analyze Roxadustat in the biological matrix. The literature needs more data on forced degradation study, impurity profiling, gas chromatography, analytical methods for assay, dissolution, and different formulation aspects of Roxadustat.

ISPD peritonitis guideline recommendations: 2022 update on prevention and treatment

Peritoneal dialysis (PD)-associated peritonitis is a serious complication of PD and prevention and treatment of such is important in reducing patient morbidity and mortality. The ISPD 2022 updated recommendations have revised and clarified definitions for refractory peritonitis, relapsing peritonitis, peritonitis-associated catheter removal, PD-associated haemodialysis transfer, peritonitis-associated death and peritonitis-associated hospitalisation. New peritonitis categories and outcomes including pre-PD peritonitis, enteric peritonitis, catheter-related peritonitis and medical cure are defined. The new targets recommended for overall peritonitis rate should be no more than 0.40 episodes per year at risk and the percentage of patients free of peritonitis per unit time should be targeted at >80% per year. Revised recommendations regarding management of contamination of PD systems, antibiotic prophylaxis for invasive procedures and PD training and reassessment are included. New recommendations regarding management of modifiable peritonitis risk factors like domestic pets, hypokalaemia and histamine-2 receptor antagonists are highlighted. Updated recommendations regarding empirical antibiotic selection and dosage of antibiotics and also treatment of peritonitis due to specific microorganisms are made with new recommendation regarding adjunctive oral N-acetylcysteine therapy for mitigating aminoglycoside ototoxicity. Areas for future research in prevention and treatment of PD-related peritonitis are suggested.

Design and Rationale of HiLo: A Pragmatic, Randomized Trial of Phosphate Management for Patients Receiving Maintenance Hemodialysis

RATIONALE & OBJECTIVE

Hyperphosphatemia is a risk factor for poor clinical outcomes in patients with kidney failure receiving maintenance dialysis. Opinion-based clinical practice guidelines recommend the use of phosphate binders and dietary phosphate restriction to lower serum phosphate levels toward the normal range in patients receiving maintenance dialysis, but the benefits of these approaches and the optimal serum phosphate target have not been tested in randomized trials. It is also unknown if aggressive treatment that achieves unnecessarily low serum phosphate levels worsens outcomes.

STUDY DESIGN

Multicenter, pragmatic, cluster-randomized clinical trial.

SETTING & PARTICIPANTS

HiLo will randomize 80-120 dialysis facilities operated by DaVita Inc and the University of Utah to enroll 4,400 patients undergoing 3-times-weekly, in-center hemodialysis.

INTERVENTION

Phosphate binder prescriptions and dietary recommendations to achieve the "Hi" serum phosphate target (≥6.5 mg/dL) or the "Lo" serum phosphate target (<5.5 mg/dL).

OUTCOMES

Primary outcome: Hierarchical composite outcome of all-cause mortality and all-cause hospitalization. Main secondary outcomes: Individual components of the primary outcome.

RESULTS

The trial is currently enrolling.

LIMITATIONS

HiLo will not adjudicate causes of hospitalizations or mortality and does not protocolize use of specific phosphate binder classes.

CONCLUSIONS

HiLo aims to address an important clinical question while more generally advancing methods for pragmatic clinical trials in nephrology by introducing multiple innovative features including stakeholder engagement in the study design, liberal eligibility criteria, use of electronic informed consent, engagement of dietitians to implement the interventions in real-world practice, leveraging electronic health records to eliminate dedicated study visits, remote monitoring of serum phosphate separation between trial arms, and use of a novel hierarchical composite outcome.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study number NCT04095039.

The impact of intraperitoneal antibiotic administration in patients with peritoneal dialysis-related peritonitis: systematic review and meta-analysis

Background

Peritonitis is a common and clinically important complication in patients receiving peritoneal dialysis (PD). Antibiotic administration is essential for PD-related peritonitis, but routes of administration have not been established enough. Here, we performed a systematic review to assess the efficacy and safety of intraperitoneal (IP) antibiotic administration compared to intravenous (IV) antibiotic administration in patients with PD-related peritonitis.

Methods

Cochrane CENTRAL, MEDLINE, and Ichushi-Web were searched in June 2017. Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were followed, and articles were screened by four independent reviewers.

Results

Two randomized controlled trials (113 patients) were identified. IP antibiotic administration was more effective than IV antibiotic administration. The pooled risk difference between IP and IV was 0.13 (95% CI − 0.17 to 0.43). Safety assessment indicated less frequency of side effects in patients receiving IP antibiotic administration. The pooled risk ratios of IV to IP regarding adverse drug reaction-related and administration route-related side effects were 5.13 (0.63 to 41.59) and 3.00 (0.14 to 65.90), respectively.

Conclusion

The systematic review and meta-analysis suggested that IP antibiotic administration is more effective and safer in patients with PD-related peritonitis compared to IV antibiotic administration.

Clinical Evaluation of the Safety, Efficacy and Tolerability of Lanthanum Carbonate in the Management of Hyperphosphatemia in Patients with End-Stage Renal Disease

Patients with progressive chronic kidney disease (CKD) commonly develop mineral and bone abnormalities and extraskeletal calcifications with following increased cardiovascular risk. A key pathophysiological role is played by hyperphosphatemia. Since diet and dialysis are often insufficient to control serum phosphorus levels, many patients require treatment with phosphate binders. Among them is lanthanum carbonate, an aluminum-free non-calcium-based compound. The present review summarizes the most recent literature data concerning the safety, efficacy and tolerability of lanthanum carbonate in patients with end-stage renal disease and hyperphosphatemia. The drug is taken orally as chewable tablets or powder with only minimal gastrointestinal absorption and resulting reduced risk of tissue deposition and systemic drug interactions. The dissociation of the drug in the acid environment of the upper gastrointestinal tract induces the release of lanthanum ions, which bind to dietary phosphate forming insoluble complexes then excreted in the feces. Even though there is no clear evidence that lowering serum phosphorus levels can improve patient-centered outcomes, a mortality benefit with all phosphate binders, especially non-calcium containing ones, is not excluded. Lanthanum carbonate has been suggested to decrease all-cause mortality but not cardiovascular event rate compared to other phosphate binders. It induces a lower suppression of bone turnover than calcium carbonate and calcium acetate and may improve systolic function and cardiac dimension compared to calcium carbonate. Moreover, the use of lanthanum carbonate has been associated with better nutritional status compared to other phosphate binders, lower risk for hypercalcemia than calcium-containing binders, and amelioration of mild metabolic acidosis contrary to sevelamer hydrochloride. Main adverse effects include nausea, alkaline gastric reflux, gastric deposition of lanthanum, gastrointestinal obstruction, subileus, ileus, perforation, fecal impaction, and reduction of gastrointestinal absorption of some drugs including statins, angiotensin-converting enzyme inhibitors and some antibiotics such as fluoroquinolones or tetracyclines.

Improving antibacterial prescribing safety in the management of COPD exacerbations: systematic review of observational and clinical studies on potential drug interactions associated with frequently prescribed antibacterials among COPD patients

Background

Guidelines advise the use of antibacterials (ABs) in the management of COPD exacerbations. COPD patients often have multiple comorbidities, such as diabetes mellitus and cardiac diseases, leading to polypharmacy. Consequently, drug–drug interactions (DDIs) may frequently occur, and may cause serious adverse events and treatment failure.

Objectives

(i) To review DDIs related to frequently prescribed ABs among COPD patients from observational and clinical studies. (ii) To improve AB prescribing safety in clinical practice by structuring DDIs according to comorbidities of COPD.

Methods

We conducted a systematic review by searching PubMed and Embase up to 8 February 2018 for clinical trials, cohort and case–control studies reporting DDIs of ABs used for COPD. Study design, subjects, sample size, pharmacological mechanism of DDI and effect of interaction were extracted. We evaluated levels of DDIs and quality of evidence according to established criteria and structured the data by possible comorbidities.

Results

In all, 318 articles were eligible for review, describing a wide range of drugs used for comorbidities and their potential DDIs with ABs. DDIs between ABs and co-administered drugs could be subdivided into: (i) co-administered drugs altering the pharmacokinetics of ABs; and (ii) ABs interfering with the pharmacokinetics of co-administered drugs. The DDIs could lead to therapeutic failures or toxicities.

Conclusions

DDIs related to ABs with clinical significance may involve a wide range of indicated drugs to treat comorbidities in COPD. The evidence presented can support (computer-supported) decision-making by health practitioners when prescribing ABs during COPD exacerbations in the case of co-medication.

Concurrent administration with multivalent metal cation preparations or polycationic polymer preparations inhibits the absorption of raltegravir via its chelation

OBJECTIVES

Raltegravir (RAL) that can form chelates with multivalent metal cations shows lateral interactions with multivalent metal cation and polycationic polymer. We investigated the interactions of RAL with multivalent metal cation preparations, Al(OH)₃ and LaCO₃ , and polycationic polymer preparations, bixalomer (Bxl) and sevelamer (Svl).

METHODS

Immediately before the oral administration of 40 mg/kg RAL, the rats were administered orally with the vehicle, Al(OH)₃ , LaCO₃ , Bxl, or Svl, and the time course of RAL serum concentration was followed. The in vitro binding affinity of RAL with multivalent metal cation and polycationic polymer was also evaluated using isothermal titration calorimetry (ITC).

RESULTS

When Al(OH)₃ , LaCO₃ , Bxl, or Svl was concomitantly administered with RAL, the maximum concentration and area under the curve were significantly lower than those when RAL was administered alone. ITC showed the interaction of RAL with Al(OH)₃ as an enthalpy-driven reaction and its interactions with LaCO₃ and Bxl as entropy-enthalpy mixed reactions.

CONCLUSIONS

The interaction of RAL with Al(OH)₃ , LaCO_3, Bxl, or Svl can inhibit RAL absorption into the gastrointestinal tract, and thus, the multivalent metal cation and polycationic polymer are the modifying factors that can affect RAL pharmacokinetics.

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.

Compatibility of ciprofloxacin with commercial peritoneal dialysis solutions

Intraperitoneal administration of antibiotics together with peritoneal dialysis fluids (PDFs) remains the preferable route for treatment of peritoneal dialysis-related peritonitis. For home based therapy, antibiotic-containing PDFs are stored for up to two weeks and warmed up to body-temperature before administration. The present study investigated the compatibility of ciprofloxacin with five commercial PDFs at refrigeration-temperature, room-temperature and body-temperature. Ciprofloxacin concentrations were determined using high-performance liquid chromatography. Drug-diluent stability was evaluated by measurement of pH-values and visual inspection at each sampling point. The antimicrobial activity of ciprofloxacin was assessed by an E. coli disk diffusion method. Ciprofloxacin was stable at refrigeration-temperature and body-temperature in all PDFs evaluated over the whole study period of 14 days and 24 hours, respectively. At room-temperature, in contrast, ciprofloxacin demonstrated only limited stability in particular when tested in mixed Physioneal. Except for Physioneal 1.36%, no relevant drug adsorption was observed and the antimicrobial activity of ciprofloxacin was found to be preserved in each PDF at each storage condition investigated. Intraperitoneal ciprofloxacin might be used for inpatient and home based therapy of peritoneal dialysis-related peritonitis and no compensatory dose adjustment is needed when stored for up to two weeks at refrigeration-temperature before use.

Concentration-Dependent Dual Effects of Ciprofloxacin on SB-590885-Resistant BRAFV600E A375 Melanoma Cells

BRAF inhibitors (BRAFi) have been applied to treat melanoma harboring V600E mutations. Several studies showed that BRAFi-resistant melanomas are dependent on mitochondrial biogenesis. Therefore, the present study aimed to investigate the influence of ciprofloxacin (CIP), a mitochondria-targeting antibiotic, on SB-590885-resistant BRAF^V600E A375 melanoma (A375/SB) cells. The cytotoxicity activity of CIP and SB-590885, a potent and specific BRAFi, on A375 and A375/SB cells was evaluated by MTT, colony formation, migration, and spheroid formation assays. Moreover, SB-590885-induced cell death in A375 cells was analyzed. SB-590885 showed time- and concentration-dependent cytotoxic effects on A375 cells. Twenty-five μg/mL CIP decreased the cell viability of A375 and A375/SB cells in a time-dependent manner. This concentration of CIP markedly decreased clonogenicity in both cells and caused a reduction in the growth of A375/SB spheroids. The cytotoxicity of 5 μg/mL CIP on A375/SB cells was less than that of A375 cells. The colony formation and migration ability of A375/SB cells was increased in the presence of 5 μg/mL CIP. Ten μM SB-590885 induced a massive vacuolization in A375 cells. Cell death assays suggested a simultaneous activation of autophagy, paraptosis, apoptosis, and necrosis. For the first time, this study reveals that CIP at the maximum concentration in serum (5 μg/mL) can enhance the colony formation and migration abilities in BRAFi-resistant melanoma cells, while it has cytotoxic activity against these cells at a higher concentration than serum level. This study suggests that CIP may promote aggressive growth properties in BRAFi-resistant melanomas, at a concentration present in serum.

Ciprofloxacin mediates cancer stem cell phenotypes in lung cancer cells through caveolin-1-dependent mechanism

Cancer stem cells (CSCs), a subpopulation of cancer cells with high aggressive behaviors, have been identified in many types of cancer including lung cancer as one of the key mediators driving cancer progression and metastasis. Here, we have reported for the first time that ciprofloxacin (CIP), a widely used anti-microbial drug, has a potentiating effect on CSC-like features in human non-small cell lung cancer (NSCLC) cells. CIP treatment promoted CSC-like phenotypes, including enhanced anchorage-independent growth and spheroid formation. The known lung CSC markers: CD133, CD44, ABCG2 and ALDH1A1 were found to be significantly increased, while the factors involving in epithelial to mesenchymal transition (EMT): Slug and Snail, were depleted. Also, self-renewal transcription factors Oct-4 and Nanog were found to be up-regulated in CIP-treated cells. The treatment of CIP on CSC-rich populations obtained from secondary spheroids resulted in the further increase of CSC markers. In addition, we have proven that the mechanistic insight of the CIP induced stemness is through Caveolin-1 (Cav-1)-dependent mechanism. The specific suppression of Cav-1 by stably transfected Cav-1 shRNA plasmid dramatically reduced the effect of CIP on CSC markers as well as the CIP-induced spheroid formation ability. Cav-1 was shown to activate protein kinase B (Akt) and extracellular signal-regulated kinase (ERK) pathways in CSC-rich population; however, such an effect was rarely found in the main lung cancer cells population. These findings reveal a novel effect of CIP in positively regulating CSCs in lung cancer cells via the activation of Cav-1, Akt and ERK, and may provoke the awareness of appropriate therapeutic strategy in cancer patients.

Phosphate binders for the treatment of hyperphosphatemia in chronic kidney disease patients on dialysis: a comparison of safety profiles

INTRODUCTION

Hyperphosphatemia is common in the late stages of chronic kidney disease (CKD) and is associated with elevated parathormone levels, abnormal bone mineralization, extraosseous calcification and increased risk of cardiovascular events and death. Several classes of oral phosphate binders are available to help control phosphorus levels. Although effective at lowering serum phosphorus, they all have safety issues that need to be considered when selecting which one to use.

AREAS COVERED

This paper reviews the use of phosphate binders in patients with CKD on dialysis, with a focus on safety and tolerability. In addition to the more established agents, a new resin-based phosphate binder, colestilan, is discussed.

EXPERT OPINION

Optimal phosphate control is still an unmet need in CKD. Nonetheless, we now have an extending range of phosphate binders available. Aluminium has potentially serious toxic risks. Calcium-based binders are still very useful but can lead to hypercalcemia and/or positive calcium balance and cardiovascular calcification. No long-term data are available for the new calcium acetate/magnesium combination product. Lanthanum is an effective phosphate binder, but there is insufficient evidence about possible long-term effects of tissue deposition. The resin-based binders, colestilan and sevelamer, appear to have profiles that would lead to less vascular calcification, and the main adverse events seen with these agents are gastrointestinal effects.

Release behavior and toxicity profiles towards A549 cell lines of ciprofloxacin from its layered zinc hydroxide intercalation compound

Background

Layered hydroxides salts (LHS), a layered inorganic compound is gaining attention in a wide range of applications, particularly due to its unique anion exchange properties. In this work, layered zinc hydroxide nitrate (LZH), a family member of LHS was intercalated with anionic ciprofloxacin (CFX), a broad spectrum antibiotic via ion exchange in a mixture solution of water:ethanol.

Results

Powder x-ray diffraction (XRD), Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) confirmed the drug anions were successfully intercalated in the interlayer space of LZH. Specific surface area of the obtained compound was increased compared to that of the host due to the different pore textures between the two materials. CFX anions were slowly released over 80 hours in phosphate-buffered saline (PBS) solution due to strong interactions that occurred between the intercalated anions and the host lattices. The intercalation compound demonstrated enhanced antiproliferative effects towards A549 cancer cells compared to the toxicity of CFX alone.

Conclusions

Strong host-guest interactions between the LZH lattice and the CFX anion give rise to a new intercalation compound that demonstrates sustained release mode and enhanced toxicity effects towards A549 cell lines. These findings should serve as foundations towards further developments of the brucite-like host material in drug delivery systems.

Inappropriate use of nonsteroidal anti-inflammatory drugs and other drugs in chronic kidney disease patients without renal replacement therapy

OBJECTIVE

The main goal of chronic kidney disease (CKD) treatment is the prevention of progression of the disease and complications. Inappropriate drug use in patients with CKD is an important issue, which may cause adverse effects on patients and progression of chronic renal failure. The aim of this study is to find the rate of inappropriate drug use among CKD patients.

METHODS

The subjects of this study were selected from the patients with a CKD history of minimum one year, who did not receive renal replacement therapy. Patients were asked to provide a digital record of the drugs they used over the last one year. Individually, for each patient, the drugs that may be contraindicative and that require dose adjustment were identified based on glomerular filtration rate (GFR).

RESULTS

This study includes a total of 185 participants - 97 female (52.4%) and 88 male (47.6%) patients. The average age of patients was 60.50 ± 14.56. It was shown that 149 patients (80.5%) were using inappropriate drugs. Seventy (47.0%) were using one, 79 (53.0%) two, 30 (20/1%) three, and 9 (6.4%) four inappropriate drugs. Of CKD patients, 44.3% were aged 65 or over; and in this age group, inappropriate drug use was more frequent compared to the population below 65 (86.6% vs. 75.7%). The drugs used inappropriately were, respectively, nonsteroidal anti-inflammatory drugs (65.8%), quinolone antibiotics (39.0%), ACE inhibitors (26.9%).

DISCUSSION

Health professionals are required to consider renal functions of all patients, mainly those aged over 65, when administering a treatment.

Ferric citrate: a novel phosphate-binding agent

Ferric citrate (KRX-0502; Keryx Biopharmaceuticals, Inc., NY, USA) is a novel phosphate-binding agent presently in Phase III clinical development. Ferric citrate dissociates in the bowel lumen releasing the ferric ion to precipitate with dietary phosphorus, which is then excreted in the stool. Studies to date have shown the agent to be efficacious and safe with only mild gastrointestinal side effects. Absorption of either component of the agent (ferric iron or citrate) has the potential to be of benefit for patients with end-stage renal disease. An ongoing Phase III trial is confirming the safety and efficacy of ferric citrate as a phosphate binder in dialysis patients.

Rationale and study design of a three-period, 58-week trial of ferric citrate as a phosphate binder in patients with ESRD on dialysis

Chronic kidney disease associated mineral and bone disorders arise as a result of aberrant bone mineral metabolism in patients with advancing levels of renal dysfunction and end-stage renal disease. One of the cornerstones of treatment is the use of phosphate-binding agents. We describe the rationale and study design for a clinical trial to assess the safety and efficacy of ferric citrate as a phosphate binder. This trial is a three-period, international, multicenter, randomized, controlled clinical trial to assess the safety and efficacy of ferric citrate as a phosphate binder, consisting of a 2-week washout period, a 52-week safety assessment period in which subjects are randomized to ferric citrate or active control, and a 4-week efficacy assessment period in which subjects randomized to ferric citrate in the safety assessment period are randomized to ferric citrate or placebo. Eligible subjects include end-stage renal disease patients who have been treated with thrice-weekly hemodialysis or peritoneal dialysis for at least 3 months in dialysis clinics in the United States and Israel. Primary outcome measure will be the effect of ferric citrate vs. placebo on the change in serum phosphorus. Safety assessments will be performed by monitoring adverse events, concomitant medication use, and sequential blood chemistries (including iron parameters, phosphorus, and calcium). This three-period trial will assess the efficacy of ferric citrate as a phosphate binder. If proven safe and efficacious, ferric citrate will likely provide an additional phosphate binder to treat chronic kidney disease associated mineral and bone disorders.

Pharmacokinetic drug interactions of antimicrobial drugs: a systematic review on oxazolidinones, rifamycines, macrolides, fluoroquinolones, and Beta-lactams

Like any other drug, antimicrobial drugs are prone to pharmacokinetic drug interactions. These drug interactions are a major concern in clinical practice as they may have an effect on efficacy and toxicity. This article provides an overview of all published pharmacokinetic studies on drug interactions of the commonly prescribed antimicrobial drugs oxazolidinones, rifamycines, macrolides, fluoroquinolones, and beta-lactams, focusing on systematic research. We describe drug-food and drug-drug interaction studies in humans, affecting antimicrobial drugs as well as concomitantly administered drugs. Since knowledge about mechanisms is of paramount importance for adequate management of drug interactions, the most plausible underlying mechanism of the drug interaction is provided when available. This overview can be used in daily practice to support the management of pharmacokinetic drug interactions of antimicrobial drugs.

Sevelamer carbonate for the treatment of hyperphosphatemia in patients with kidney failure (CKD III - V)

IMPORTANCE OF THE FIELD

Altered mineral metabolism in chronic kidney disease (CKD) is associated with increased morbidity, mortality, hospitalization, cost of care and reduced quality of life. Phosphorus control, one component of CKD metabolic derangements, is potentially related to impaired outcomes and has significant room for improvement.

AREAS COVERED IN THIS REVIEW

Historical, present and future aspects of treatment of hyperphosphatemia focusing on sevelamer hydrochloride and sevelamer carbonate.

WHAT THE READER WILL GAIN

Comprehensive insight into the background and controversies regarding phosphate binders.

TAKE HOME MESSAGE

While calcium-free phosphate binders with a sevelamer backbone may offer therapeutic advantages for CKD patients at risk, more studies comprising significant patient numbers are warranted to answer compelling clinical questions.

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.

Lanthanum carbonate for hyperphosphatemia in patients with advanced CKD and patients receiving dialysis

Reduced renal excretion of phosphate leads to hyperphosphatemia, which is prevalent in patients with end-stage renal disease, and is associated with increased morbidity and mortality. Dialysis alone is unable to adequately remove the ingested phosphate contained in food. It is therefore usually necessary to supplement food with drugs that reduce the intestinal absorption of dietary phosphate in order to control serum phosphate. Lanthanum carbonate is a recently introduced nonaluminum, noncalcium phosphate binder licensed for the management of serum phosphate in end-stage renal failure. It appears safe and effective, with data demonstrating no toxic effects in man after continuous exposure for up to 6 years. It is well tolerated and has a positive effect on bone histology in the context of renal osteodystrophy. Lanthanum carbonate's high affinity for phosphate rapid binding, palatability, low pill burden and absence of evident toxicity compare favorably with what are considered to be the ideal characteristics of an oral phosphate binder.

Pharmacokinetics and dosage adjustment in patients with renal dysfunction

INTRODUCTION

Chronic kidney disease is a common, progressive illness that is becoming a global public health problem. In patients with kidney dysfunction, the renal excretion of parent drug and/or its metabolites will be impaired, leading to their excessive accumulation in the body. In addition, the plasma protein binding of drugs may be significantly reduced, which in turn could influence the pharmacokinetic processes of distribution and elimination. The activity of several drug-metabolizing enzymes and drug transporters has been shown to be impaired in chronic renal failure. In patients with end-stage renal disease, dialysis techniques such as hemodialysis and continuous ambulatory peritoneal dialysis may remove drugs from the body, necessitating dosage adjustment.

METHODS

Inappropriate dosing in patients with renal dysfunction can cause toxicity or ineffective therapy. Therefore, the normal dosage regimen of a drug may have to be adjusted in a patient with renal dysfunction. Dosage adjustment is based on the remaining kidney function, most often estimated on the basis of the patient's glomerular filtration rate (GFR) estimated by the Cockroft-Gault formula. Net renal excretion of drug is a combination of three processes: glomerular filtration, tubular secretion and tubular reabsorption. Therefore, dosage adjustment based on GFR may not always be appropriate and a re-evaluation of markers of renal function may be required.

DISCUSSION

According to EMEA and FDA guidelines, a pharmacokinetic study should be carried out during the development phase of a new drug that is likely to be used in patients with renal dysfunction and whose pharmacokinetics are likely to be significantly altered in these patients. This study should be carried out in carefully selected subjects with varying degrees of renal dysfunction. In addition to this two-stage pharmacokinetic approach, a population PK/PD study in patients participating in phase II/phase III clinical trials can also be used to assess the impact of renal dysfunction on the drug's pharmacokinetics and pharmacodynamics.

CONCLUSION

In conclusion, renal dysfunction affects more that just the renal handling of drugs and/or active drug metabolites. Even when the dosage adjustment recommended for patients with renal dysfunction are carefully followed, adverse drug reactions remain common.

Clinical pharmacokinetics of the phosphate binder lanthanum carbonate

Lanthanum carbonate is considered to be the most potent of a new generation of noncalcium phosphate binders used to treat hyperphosphataemia in chronic kidney disease (CKD), a condition associated with progressive bone and cardiovascular pathology and a markedly elevated risk of death. Its phosphate-binding action involves ionic binding and precipitation of insoluble complexes within the lumen of the intestine, thereby preventing absorption of dietary phosphate. While pharmacokinetics have little relevance to the efficacy of lanthanum carbonate, they are of fundamental importance when it comes to evaluating safety. When administered as lanthanum carbonate, the oral bioavailability of lanthanum is low (approximately 0.001%). The small absorbed fraction is excreted predominantly in bile, with less than 2% being eliminated by the kidneys. Predictably, therefore, plasma exposure and pharmacokinetics have been shown to be similar in healthy human volunteers and CKD stage 5 patients. With almost complete plasma protein binding, free lanthanum concentrations in patients at steady state are <3 pg/mL. These properties greatly reduce systemic exposure, tissue deposition and the potential for adverse effects. While lanthanum has a variety of calcium-like actions in vitro, there is little or no evidence that these occur in vivo. This paradox is explained by the very low concentrations of circulating free lanthanum ions, which are many orders of magnitude lower than reported effect concentrations in vitro. Safety pharmacology and toxicology evaluations have failed to reveal any significant calcium-like actions in vivo, despite inclusion of high intravenous doses in some cases.Lanthanum carbonate has a low propensity to cause systemic drug interactions due to its poor absorption. However, the higher concentrations present in the gastrointestinal tract can form chelates with some drugs, such as fluoroquinolones, and reduce their absorption. The improved understanding of the pharmacokinetics of lanthanum that has emerged in recent years has helped to explain why the myriad of calcium-like effects described in vitro for lanthanum have little if any relevance in vivo. The pharmacokinetic investigations of lanthanum carbonate formed an important part of the stringent premarketing safety assessment process and have been influential in reassuring both regulators and physicians that the agent can be used safely and effectively in this vulnerable dialysis population.