Vancomycin removal by high-flux polysulfone hemodialysis membranes in critically ill patients with end-stage renal disease

Removal of common antimicrobial agents by sustained low-efficiency dialysis

Adequate dosing of antimicrobials is paramount for treating infections in critically ill patients undergoing kidney replacement therapy; however, little is known about antimicrobial removal by sustained low-efficiency dialysis (SLED). The objective was to quantify the removal of cefepime, daptomycin, meropenem, piperacillin-tazobactam, and vancomycin in patients undergoing SLED. Adult patients ≥18 years with acute kidney injury (AKI) or end-stage kidney disease receiving one of the select antimicrobials and requiring SLED were included. Blood and dialysate flow rates were maintained at 250 and 100 mL/min, respectively. Simultaneous arterial and venous blood samples for the analysis of antibiotic concentrations were collected hourly for 8 hours during SLED (on-SLED). Arterial samples were collected every 2 hours for up to 6 hours while not receiving SLED (off-SLED) for the calculation of SLED clearance, half-life (t1/2) on-SLED and off-SLED, and the fraction of removal by SLED (fD). Twenty-one patients completed the study: 52% male, mean age (±SD) 53 ± 13 years, and mean weight of 98 ± 30 kg. Eighty-six percent had AKI, and 4 patients were receiving cefepime, 3 daptomycin, 10 meropenem, 6 piperacillin-tazobactam, and 13 vancomycin. The average SLED time was 7.3 ± 1.1 hours, and the mean ultrafiltration rate was 95 ± 52 mL/hour (range 10-211). The t1/2 on-SLED was substantially lower than the off-SLED t1/2 for all antimicrobials, and the SLED fD varied between 44% and 77%. An 8-hour SLED session led to significant elimination of most antimicrobials evaluated. If SLED is performed, modification of the dosing regimen is warranted to avoid subtherapeutic concentrations.

Practices, Knowledge, and Attitudes of Nephrologists Towards Prescribing and Monitoring Vancomycin at Dialysis Centers

BACKGROUND

Vancomycin dosing protocols are varied in the literature for hemodialysis patients. This study sought to determine nephrologists' practices, knowledge, attitudes, and barriers toward prescribing and monitoring vancomycin at dialysis centers.

METHODS

A cross-sectional and multi-center study was conducted in Kuwait using a validated self-administered questionnaire among 168 nephrologists. Descriptive and comparative analyses were performed using SPSS (version 28).

RESULTS

The response rate was 75% (n = 126). Over half of nephrologists frequently prescribed a vancomycin loading dose of 1000 mg (53.2%) and a maintenance dose of 500 mg (51.6%) to all patients. Their overall median (IQR) percentage knowledge about the therapeutic monitoring of vancomycin was 66.7% (33.3) and was found to be higher in nephrologists aged ≤ 40 years and in registrars/senior registrars (p < 0.05). Their overall median (IQR) attitude score was 4.0 (1.0) [positive attitude]. Nephrologists with > 15 years of practice experience expressed higher attitudes (p < 0.05). The top two perceived barriers were a lack of clear local hospital/national guidelines (60.3%) for vancomycin dosing in dialysis and inconsistencies among different dosing references and guidelines (51.6%).

CONCLUSION

Findings showed that nephrologists have varying practices, moderate knowledge, and positive attitudes toward prescribing and monitoring vancomycin and highlight the need for interventions to overcome the perceived barriers.

Comparison of antimicrobial dosing recommendations in patients receiving intermittent hemodialysis among drug information resources

WHAT IS KNOWN AND OBJECTIVE

Tertiary drug information resources are frequently consulted for the optimal antimicrobial dosing in intermittent hemodialysis (IHD) patients. Yet, significant discrepancy may exist in dosing recommendations between resources. This study was to evaluate the consistency of antimicrobial dosing recommendations in IHD among four different drug information resources and the relevance of referenced pharmacokinetic studies.

METHODS

Dosing recommendations of 29 commonly prescribed antimicrobials in IHD patients were collected from Micromedex, LexiComp, Clinical Pharmacology and Drug Prescribing in Renal Impairment to compare dosing categorization and the total daily dose (TDD). Significant dosing discrepancies were defined as ≥30% difference. Referenced pharmacokinetic studies were evaluated for their relevance in current practice, using sample size, hemodialyzer types, the use of optimal pharmacodynamic targets and the consideration of different interdialytic dosing periods.

RESULTS AND DISCUSSION

A significant variation was found both in dosing categorization and recommended doses between resources. Seventeen drugs were compared for TDD with significant dosing discrepancy in 8 drugs. Among 42 referenced pharmacokinetic studies, 40 were evaluated. Mean patient numbers of pharmacokinetic studies were 13 ranging from 3 to 70. Sixty per cent of studies utilized contemporary hemodialyzers (e.g., high-flux and/or high efficiency). The optimal pharmacodynamic targets and the impact of different interdialytic intervals were assessed only in 27.5% and 7.5% respectively.

WHAT IS NEW AND CONCLUSION

Inconsistent antimicrobial dosing recommendations for IHD patients exist among four well-established resources. Many referenced pharmacokinetic studies utilized outdated or less pharmacodynamically relevant study methods. Newer studies are warranted to reflect contemporary dialysis practice and assess its impact on optimal antimicrobial dosing.

Pharmacokinetics and dosing of vancomycin in patients undergoing sustained low efficiency daily diafiltration (SLEDD-f): A prospective study

BACKGROUND/PURPOSE

The pharmacokinetics of vancomycin in patients who undergo sustained low efficiency daily diafiltration (SLEDD-f) is not clear. This study aimed to determine the appropriate vancomycin dosage regimen for patients receiving SLEDD-f.

METHODS

This prospectively observational study enrolled critically ill patients older than 18 years old that used SLEDD-f as renal replacement therapy and received vancomycin treatment. An 8-h SLEDD-f was performed with FX-60 (high-flux helixone membrane, 1.4 m²). Serial blood samples were collected before, during, and after SLEDD-f to analyse vancomycin serum concentrations. Effluent fluid samples (a mixture of dialysate and ultrafiltrate) were also collected to determine the amount of vancomycin removal.

RESULTS

Seventeen patients were enrolled, and 10 completed the study. The amount of vancomycin removal was 447.4 ± 88.8 mg (about 78.4 ± 18.4% of the dose administered before SLEDD-f). The vancomycin concentration was reduced by 57.5 ± 14.9% during SLEDD-f, and this reduction was followed by a rebound with duration of one to three hours. The elimination half-life of vancomycin decreased from 64.1 ± 35.7 h before SLEDD-f to 7.0 ± 3.0 h during SLEDD-f.

CONCLUSION

Significant amount of vancomycin removed during SLEDD-f. Despite the existence of post-dialysis rebound, a sufficient supplemental dose is necessary to maintain therapeutic range.

Effective treatment of vancomycin nephrotoxicity with continuous venous-venous haemodiafiltration (CVVHDF) in a paediatric patient

WHAT IS KNOWN AND OBJECTIVE

Vancomycin removal by dialysis uses methods that differ in type of dialysis membrane, dialysis fluxes and duration, ultrafiltration rate and Kt/V_urea (K = dialyser urea clearance, t = time on dialysis and V = total body water) in case of nephrotoxicity. We applied continuous venous-venous haemodiafiltration (CVVHDF) to treat a paediatric case of vancomycin nephrotoxicity caused by high serum trough concentrations.

CASE SUMMARY

We report the case of a 4-year and 7-month-old boy with serum trough concentration of vancomycin of 86.0 mg/L after a 2-day treatment with vancomycin. His serum creatinine increased from 13.3 μmol/L at baseline to 227.0 μmol/L. We discontinued vancomycin and performed a 22-hours CVVHDF with high-flux membrane. Vancomycin decreased by 69.4% (82.1-25.1 mg/L), and renal function improved.

WHAT IS NEW AND CONCLUSION

Therapeutic drug monitoring and laboratory indicator measurements should be performed early during vancomycin treatment in paediatric patients with nephrotoxicity risk factors. Vancomycin removal by CVVHDF can be effective in paediatric acute kidney injury (AKI) associated with vancomycin-associated nephrotoxicity (VAN).

Status of Hemodialysis of Drugs in 2002

Hemodialysis is a life-sustaining chronic therapy for individuals with end stage renal disease (ESRD). It is also frequently used for days to weeks for patients with acute renal failure who are awaiting the recovery of their kidneys from the acute toxic or traumatic event. Both populations of patients often require complex pharmacotherapeutic regimens, and it is not uncommon for them to be receiving 10 or more concomitant medications. Optimization of care for these patients is dependent on the selection of the most appropriate drug as well as dosage regimen design, which accounts for the influence of hemodialysis therapy on drug disposition. During the last 10 to 15 years there have been several significant changes in the prescribed dose of dialysis and the composition and size of dialyzers available for use. Furthermore, reuse of dialyzers, which was rare in the early 1980s, is now common; it is employed with over 70% of patients with ESRD. The new synthetic dialyzers, which are now used for over 60% of ESRD patients in the United States, are uniformly associated with dramatic improvements in drug removal; dialysis clearance increases of 3 to 10 fold were common for the few drugs evaluated. The influence of these changes in hemodialysis therapy on drug disposition are discussed in a quantitative fashion, and a conceptual framework for drug therapy regimen decision making is presented. For the majority of the drugs reviewed, however, there were no data in the literature regarding dialyzability with currently available dialyzers. The generation of dialyzability data for old and new pharmacotherapeutic agents with state of the art dialysis procedures is clearly needed.

Assessment of vancomycin use in chronic haemodialysis patients: room for improvement

BACKGROUND

Vancomycin is frequently prescribed for the management of infections in haemodialysis patients. We evaluated the appropriateness of vancomycin use in our chronic haemodialysis population.

METHODS

Charts of all chronic haemodialysis patients who received vancomycin between 1 March 2003 and 1 March 2004 were retrospectively reviewed. Indication was assessed according to the modified Hospital Infection Control Practices Advisory Committee guidelines for vancomycin prescription. The prescribed dosing regimens were evaluated.

RESULTS

A total of 163 courses of vancomycin in 105 patients were assessed. Of all courses, 88% were considered to be initially appropriate, but this decreased to 63% once culture and sensitivity results were available. Use of vancomycin for the management of beta-lactam-sensitive organisms accounted for the majority of inappropriate use. The most common vancomycin-dosing regimen prescribed was 500 mg intravenously at each haemodialysis session (51%); however, considerable variability was observed.

CONCLUSIONS

Although the initial indication for vancomycin use was generally appropriate, inappropriate continuation of this antibiotic, failure to obtain proper cultures to guide therapy and potentially subtherapeutic dosing regimens were some of the challenges identified. Centres providing chronic haemodialysis should take steps to optimize vancomycin prescription to improve clinical outcomes and reduce the risk of antimicrobial resistance.

Pharmacokinetics and total elimination of meropenem and vancomycin in intensive care unit patients undergoing extended daily dialysis*

OBJECTIVE

Extended daily dialysis (EDD) combines the advantage of both intermittent hemodialysis and continuous renal replacement therapy: excellent detoxification accompanied by cardiovascular tolerability. The aim of this study was to evaluate pharmacokinetics of meropenem and vancomycin in critically ill patients with renal failure undergoing EDD.

DESIGN

Prospective clinical study.

SETTING

Surgical intensive care unit in a tertiary care center.

PATIENTS

We studied intensive care patients with anuric acute renal failure being treated with EDD and receiving meropenem (n = 10) or vancomycin (n = 10) therapy.

INTERVENTIONS

The antibiotics were administered 6 hrs (1.0 g meropenem) or 12 hrs (1.0 g vancomycin) before EDD was started in order to study the pharmacokinetics before and during EDD. In addition to the application of different methods to calculate pharmacokinetic parameters, the total dialysate concentration of both drugs was measured.

RESULTS

Based on the amount of the drug recovered from the collected spent dialysate, the fraction of drug removed by one dialysis treatment was 18% for meropenem and 26% for vancomycin. Dosing regimes for intermittent hemodialysis and continuous renal replacement therapy cannot be used for critically ill patients treated with EDD.

CONCLUSION

Our data suggest that patients treated with EDD by means of a high-flux dialyzer (polysulphone; surface area, 1.3 m; blood and dialysate flow, 160 mL/min; EDD time, 480 mins) and current dosing regimens run the risk of being significantly underdosed, which may have detrimental effects on critically ill patients with life-threatening infections. The exact dose has to be tailored according to weight and severity of illness as well as the current minimal inhibitory concentration against the incriminated bacteria. Whenever possible, therapeutic drug monitoring should be performed.

Adequacy of a Vancomycin Dosing Regimen in Patients Receiving High-Flux Hemodialysis

BACKGROUND

Some investigators have recommended the convenient practice of administering vancomycin doses during the last hour of the hemodialysis treatment. Accepting that a greater amount of vancomycin is lost to dialysis with this recent approach, the objective of this study is to determine the pharmacokinetics of vancomycin and assess the adequacy of this dosing regimen in maintaining therapeutic predialysis concentrations.

METHODS

A sampling of 22 consecutive patients administered intradialytic vancomycin, 1 g, intravenously (IV) and maintenance doses of 500 mg during the last hour of high-flux dialysis sessions was studied. A population-modeling program and Bayesian pharmacokinetic analysis were used to identify all global and unique pharmacokinetic parameters of interest based on measured vancomycin predialysis concentrations.

RESULTS

For the 22 patients studied, this regimen achieved the targeted predialysis concentration range of 5 to 20 microg/mL for 96% of levels, whereas more narrowly within 5 to 15 microg/mL for 86% of levels. Average amount of vancomycin removed during a standardized 3- to 4-hour dialytic session ranged from 30% +/- 7% to 38% +/- 8%. Average elimination half-life of vancomycin on hemodialysis treatment was 5.4 hours (interquartile range, 5.0 to 5.9 hours). Patients showed an average predialysis plasma concentration of 11 +/- 3 microg/mL for the first 7 days of therapy.

CONCLUSION

Our results indicate that intradialytic dosing with vancomycin using a 1-g IV load and 500 mg IV with subsequent high-flux dialysis sessions conveniently maintains adequate predialysis plasma concentrations. The lack of drug accumulation with this regimen provides convincing support for a limited blood sampling approach to plasma concentration determinations.

Clinical review: use of vancomycin in haemodialysis patients

Following intravenous administration, vancomycin is poorly metabolized and is mainly excreted unchanged in urine. Total body clearance is thus dependent on the kidney, and is correlated with glomerular filtration rate and creatinine clearance. Accumulation of vancomycin in patients with renal insufficiency may therefore occur, and this may lead to toxic side effects if dosage is not modified according to the degree of renal failure. Furthermore, vancomycin easily diffuses through dialysis membranes. The aim of the present review is to establish guidelines for handling this drug in such patients. We indicate how and when plasma concentrations of vancomycin should be determined in dialysis patients.

Vancomycin assay performance in patients with end-stage renal disease receiving hemodialysis

STUDY OBJECTIVE

To compare the performance of polyclonal fluorescence polarization immunoassay (pFPIA) with that of enzyme-multiplied immunoassay technique (EMIT) in patients receiving vancomycin and hemodialysis.

SETTING

Outpatient hemodialysis center.

PATIENTS

Seven subjects with end-stage renal disease treated with hemodialysis 3 times/week with a cellulose triacetate hemodialyzer.

INTERVENTION

Subjects received vancomycin 1000 mg intradialytically during the first study session and 750 mg every other hemodialysis session thereafter for 4 weeks.

MEASUREMENTS AND MAIN RESULTS

Blood samples were obtained throughout the study, and vancomycin serum concentrations were determined by pFPIA and EMIT. The mean +/- SD difference (estimate of bias) between assays was -1.10 +/- 1.35 mg/L. The limits of agreement (mean difference +/- 1.96 x SD) between them were -3.80-1.60 mg/L.

CONCLUSION

Our data suggest that the manufacturer's changes in the vancomycin pFPIA eliminated overestimation of drug concentrations in patients undergoing high-permeability hemodialysis.

Characterization of gentamicin pharmacokinetics in patients hemodialyzed with high-flux polysulfone membranes

To characterize the pharmacokinetics of gentamicin during and after hemodialysis (using polysulfone Fresenius F-80 membranes (Fresenius USA, Inc, Walnut Creek, CA), surface area 1.6 m(2)), eight patients with end-stage renal disease undergoing chronic hemodialysis receiving the drug for therapeutic indications were enrolled. Intradialytic gentamicin half-life, clearance, and amount of gentamicin recovered during a hemodialysis session were also determined. Serum gentamicin concentrations were analyzed using fluorescence polarization immunoassay. The amount of gentamicin recovered was 64.3 +/- 14.4 mg, whereas the intradialytic gentamicin half-life was 2.24 +/- 0.83 hours, with a clearance of 116 +/- 9 mL/min. Gentamicin concentrations rebounded by 27.86% +/- 16.4% at 1. 5 +/- 0.52 hours after the end of the hemodialysis session. The decrease in gentamicin concentrations comparing maximum rebound to prehemodialysis concentrations was 53.54% +/- 9.97%. A variable yet substantial amount of gentamicin is removed during hemodialysis using F-80 membranes; hence, supplemental doses are necessary to avoid potential treatment failures. The supplemental doses of gentamicin calculated based on gentamicin concentrations obtained immediately postdialysis could be overestimated if the postdialysis rebound concentrations are not considered. A dosing regimen is suggested using the pharmacokinetic parameters defined by the present study and population estimate of volume of distribution.

Pharmacodynamics, pharmacokinetics, and therapeutic drug monitoring of glycopeptides

The glycopeptide antibacterial drugs, vancomycin and teicoplanin, are widely used in hospitals for therapy of severe or multiresistant infection that has a positive results on Gram's stain test. Although vancomycin resistance is common in some hospital-acquired Enterococcus sp and resistance to teicoplanin occurs among Staphylococci sp glycopeptides remain the cornerstone of therapy for infection due to methicillin-resistant Staphylococcus aureus (MRSA), coagulase-negative Staphylococcus organisms, and infection related to implanted devices. Therapeutic drug monitoring (TDM) of these agents remains controversial, but advances in our understanding of their pharmacodynamics and further clinical studies are helping clarify the situation. In the future, a more rational approach to monitoring will probably result in less intensive monitoring of vancomycin but more intensive monitoring of teicoplanin.

Pharmacokinetics of drugs used in critically ill adults

Critically ill patients exhibit a range of organ dysfunctions and often require treatment with a variety of drugs including sedatives, analgesics, neuromuscular blockers, antimicrobials, inotropes and gastric acid suppressants. Understanding how organ dysfunction can alter the pharmacokinetics of drugs is a vital aspect of therapy in this patient group. Many drugs will need to be given intravenously because of gastrointestinal failure. For those occasions on which the oral route is possible, bioavailability may be altered by hypomotility, changes in gastrointestinal pH and enteral feeding. Hepatic and renal dysfunction are the primary determinants of drug clearance, and hence of steady-state drug concentrations, and of efficacy and toxicity in the individual patient. Oxidative metabolism is the main clearance mechanism for many drugs and there is increasing recognition of the importance of decreased activity of the hepatic cytochrome P450 system in critically ill patients. Renal failure is equally important with both filtration and secretion clearance mechanisms being required for the removal of parent drugs and their active metabolites. Changes in the steady-state volume of distribution are often secondary to renal failure and may lower the effective drug concentrations in the body. Failure of the central nervous system, muscle, the endothelial system and endocrine system may also affect the pharmacokinetics of specific drugs. Time-dependency of alterations in pharmacokinetic parameters is well documented for some drugs. Understanding the underlying pathophysiology in the critically ill and applying pharmacokinetic principles in selection of drug and dose regimen is, therefore, crucial to optimising the pharmacodynamic response and outcome.

Removal of vancomycin during plasmapheresis

OBJECTIVE

To examine the removal of vancomycin during plasmapheresis, determine whether drug administration should be withheld prior to or a supplemental dose given after the procedure, and determine whether a redistribution phenomenon in vancomycin serum concentrations occurs after plasmapheresis.

DESIGN

Prospective, cohort study.

SETTING

An 800-bed, tertiary-care, teaching hospital.

PATIENTS

Twelve patients receiving vancomycin as prescribed who were also undergoing therapeutic plasmapheresis.

METHODS

Blood samples for determination of vancomycin concentrations were obtained from each patient immediately before, during, immediately after, and 2 hours after plasmapheresis. Vancomycin concentration in plasma removed by plasmapheresis and volume of plasma removed were measured. Patient-specific pharmacokinetic parameters were determined for each patient using serum concentration data and a one-compartment model. Percent of drug removed by plasmapheresis and percent increase in vancomycin total clearance secondary to plasmapheresis were calculated.

RESULTS

A mean of 6.3% of the total body store of vancomycin was removed by plasmapheresis. Vancomycin clearance during plasmapheresis averaged 1.6 L/h, which was an average increase of 285% in the total clearance of vancomycin from the body. Nine of 10 patients had a higher observed vancomycin concentration 2 hours after plasmapheresis than that predicted by degrading the concentration observed immediately after the procedure, suggesting that redistribution in serum concentrations occurs after the procedure.

CONCLUSIONS

A single one-volume plasmapheresis does not remove a clinically important amount of vancomycin; therefore, supplemental dosing after the procedure is not necessary. A redistribution phenomenon in vancomycin concentrations appears to exist after plasmapheresis. Further study is needed to determine how long the redistribution phase lasts and when vancomycin concentrations should be measured after plasmapheresis.

Multiple-dose pharmacokinetics of cefpirome in long-term hemodialysis with high-flux membranes

Cefpirome is a cephalosporin eliminated primarily by kidneys that requires dosage reduction in patients with renal failure. The pharmacokinetic parameters were studied in 10 patients with end-stage renal disease who were receiving hemodialysis. Repeated intravenous administration of 2 gm cefpirome three times a week resulted in trough levels of 12.2 +/- 5.4 micrograms/ml and peak serum concentrations of 99.6 +/- 82.1 micrograms/ml. After 3 1/2 hours of hemodialysis with polysulfone high-flux membranes, 62.3% +/- 23.3% of cefpirome was removed. The interdialytic half-life was 9.35 +/- 0.99 hours, and the intradialytic half-life was 2.02 +/- 0.7 hours.

Use of vancomycin in high-flux hemodialysis: experience with 130 courses of therapy

Vancomycin is often administered to hemodialysis patients at long dosage intervals because its removal by hemodialysis is considered to be negligible. We and others, however, have demonstrated significant removal of vancomycin by high-flux hemodialysis. This report describes our experience with 89 courses of vancomycin using a revised regimen with a loading dose followed by 500 mg doses after each dialysis treatment, and compares results with 41 courses using single weekly dosing. All patients were dialyzed with high-flux membranes using volumetric ultrafiltration and bicarbonate dialysate. Serum vancomycin levels were obtained two hours after completion of infusion (peak) and immediately prior to dialysis (trough) and were measured by Abbot TDx fluorescence polarization immunoassay. Duration of multiple-dose therapy was 11 +/- 8 days, with mean total dose 3.6 +/- 1.8 g. Initial doses of 20 mg/kg rapidly and reliably established therapeutic pre-dialysis serum levels (10 to 25 micrograms/ml). In patients treated with multiple dosing 431 pre-dialysis levels were obtained. The mean level was 15.9 +/- 5.7 micrograms/ml; 55 levels (13%) were less than 10 micrograms/ml and 22 (5%) were above 25 micrograms/ml. In patients treated once weekly, 77% of levels were below 10 micrograms/ml by five days after administration, and 84% at one week. No patient developed demonstrable ototoxicity. Twenty-five patients were treated for > or = two weeks, five for > or = four weeks, and two for > five weeks, with no evidence of toxic accumulation. Mean peak level was 20.1 +/- 4.6 micrograms/ml, with a mean difference from preceding pre-dialysis level of 7.2 +/- 2.2 micrograms/ml. We conclude that in high-flux hemodialysis, a 20 mg/kg loading dose of vancomycin followed by 500 mg doses after each dialysis treatment achieves predictable, adequate and safe therapeutic levels, does not lead to unacceptably high peaks, and does not accumulate during long treatment courses. By contrast, once-weekly vancomycin dosing resulted in subtherapeutic serum levels after five to seven days, and should be abandoned in the high-flux setting.