Practical vancomycin dosing in hemodialysis patients in the era of emerging vancomycin resistance: a single-center experience

Vancomycin pharmacokinetics in patients treated with intermittent haemodialysis based on therapeutic drug monitoring

Vancomycin is frequently used in haemodialysis (HD) patients but generally accepted target serum ranges and dosing strategy are still lacking in this group. Based on retrospective analysis of data from 118 HD patients treated with vancomycin the interdialytic elimination constant (K_e), apparent volume of distribution (Vd) and dialysis efficacy were calculated. The influence of possible clinical variables on the pharmacokinetic parameters of vancomycin have been tested. The median of K_e in interdialytic periods, corresponding half-life and Vd were 0.0073 h^-1, 95.0 h and 0.87 L/kg, respectively. We found significant positive correlation between time in dialysis program and K_e. The Vd correlated best with lean body mass (LBM). For high- and low flux membrane HD of 4 hours duration the decline in vancomycin levels was 20.88% and 12.86%, respectively. Based on these data loading dose for vancomycin in HD patient should be calculated as 24.483 × LBM (kg) + 455 mg. The utility of this equation for entire HD population should be also verified prospectively.

Pharmacokinetics of Vancomycin in Pediatric Patients Receiving Intermittent Hemodialysis or Hemodiafiltration

INTRODUCTION

Vancomycin is a common antibiotic used to treat hemodialysis (HD) or hemodiafiltration (HDF)-related infections in pediatric patients, but optimal dosing remains unknown. This is the first observational study to characterize the pharmacokinetics and evaluate dosing of vancomycin in this population.

METHODS

Eligible patients received IV vancomycin 10 mg/kg per dose postdialysis followed by a series of serum vancomycin concentrations collected before, immediately after, 1 hour after, and 4 hours after dialysis. The pharmacokinetic parameters were estimated using 1- and 2-compartment models and a nonlinear least-squares algorithm.

RESULTS

Among 42 vancomycin courses in 16 patients, 1 compartment model had the best fit for observed data. The net drug removal was 43 ± 13% (39% for HD and 50% for HDF) from an average 3-hour HD/HDF session. The mean elimination constant was 0.28 h-1 (standard deviation [SD], 0.11 h-1) during the intradialytic period compared with 0.0049 h-1 (SD, 0.004 h-1) when off dialysis. The mean volume of distribution was 0.65 (SD, 0.19) L/kg. Duration of dialysis session and mode of dialysis (HD vs. HDF) were significant predictors of vancomycin pharmacokinetic parameters. Half-life was shorter for HDF compared with HD (2.1 vs. 3.5 hours).

CONCLUSIONS

Based on the simulations, an initial vancomycin dose of 10 mg/kg per dose and redosing postdialysis was optimal to achieve a vancomycin concentration range of 5 to 12 mg/L at 4 hours postdialysis and 24-hour area under the curve over minimum inhibitory concentration of ≥400 hours. Therapeutic drug monitoring is necessary to account for residual variability in vancomycin elimination in pediatric patients receiving HD/HDF.

Optimizing vancomycin dosage regimens in relation to high-flux haemodialysis

Objectives

To develop a population pharmacokinetic (PK) model for vancomycin in adults receiving high-flux haemodialysis (HFHD) in an effort to optimize vancomycin dosing in this population.

Methods

A population PK model using NONMEM was developed using retrospective data collected from 48 vancomycin courses administered to patients (n = 37) receiving HFHD. Fixed-dose [1.5 g loading dose (LD), 1 g maintenance dose (MD)], literature-adapted weight-based (WBL; 20 mg/kg LD, 10 mg/kg MD) and hospital-adapted weight-based (WBH; 25-30 mg/kg LD, 20-25 mg/kg MD) dosage regimens were then simulated using the Monte Carlo method. The PTA was an AUC24/MIC ≥400 with success being a PTA ≥90%.

Results

The data were best described using a two-compartment model. It was observed that fixed-dose and WBL dosage regimens resulted in a PTA ≤90% for most days. The WBH dosing achieved a PTA ≥90% on most days, but there were supratherapeutic concentrations with repeated dosing of vancomycin. If HFHD was delayed by 48-72 h after the LD, the PTA would fall below 90%. A dose-optimized regimen was developed: 30 mg/kg LD and 10 mg/kg MD given on HFHD days. An additional dose of 500 mg or 1 g was administered 24 h after the LD if HFHD occurred 48-72 h post-LD. This dose-optimized regimen afforded a PTA ≥90% on all days of therapy and achieved clinically acceptable pre-haemodialysis concentrations.

Conclusions

Current vancomycin dosage regimens used clinically do not achieve a PTA ≥90% for most days of therapy for people receiving HFHD. A dose-optimized regimen was developed, which could be implemented in clinical practice.

Validation of a Weight Threshold-Based Vancomycin Dosing Protocol for Patients Undergoing Intermittent Hemodialysis

BACKGROUND

Patients receiving intermittent hemodialysis (IHD) are at high risk of acquiring gram-positive infections, which are often treated with IV vancomycin. Despite frequent use of vancomycin in the IHD setting, there is variability in dosing and monitoring practices among clinicians at the study institution. There is also a paucity of evidence regarding optimal vancomycin dosing to achieve target pre-IHD serum concentration.

OBJECTIVES

The primary objective was to compare the percentage of treatment courses with a serum vancomycin concentration between 15 and 20 mg/L, measured before the third IHD session, before and after implementation of a weight threshold-based dosing protocol. The secondary objectives were to compare the percentage of treatment courses with a pre-third IHD vancomycin concentration between 10 and 22 mg/L and the number of vancomycin measurements per treatment day, before and after protocol implementation.

METHODS

This quasi-experimental, single-centre study included inpatients and outpatients who underwent IHD and received at least 2 IV doses of vancomycin, with vancomycin being measured in an appropriately drawn sample before the third IHD session. Before protocol implementation, vancomycin dosing was at the clinician's discretion (usual care). After protocol implementation, each patient received a loading dose of 1000, 1500, or 2000 mg and a maintenance dose of 500, 750, or 1000 mg, depending on body weight.

RESULTS

The percentage of treatment courses with a pre-third IHD vancomycin concentration between 15 and 20 mg/L was greater after implementation of the protocol than with usual care, but the difference was nonsignificant (44% [8/18] versus 20% [3/15], p = 0.27). However, the percentage of treatment courses with a pre-third IHD vancomycin concentration between 10 and 22 mg/L was significantly higher after protocol implementation (94% [17/18] versus 53% [8/15], p = 0.012). There was no difference in the median number of vancomycin measurements per treatment day before and after protocol implementation (0.133 versus 0.125, p = 0.99).

CONCLUSIONS

At the study institution, the likelihood of achieving recommended vancomycin concentration increased (relative to previous practice) after implementation of a simplified vancomycin dosing protocol for patients undergoing IHD.

Spanish Clinical Guidelines on Vascular Access for Haemodialysis

Vascular access for haemodialysis is key in renal patients both due to its associated morbidity and mortality and due to its impact on quality of life. The process, from the creation and maintenance of vascular access to the treatment of its complications, represents a challenge when it comes to decision-making, due to the complexity of the existing disease and the diversity of the specialities involved. With a view to finding a common approach, the Spanish Multidisciplinary Group on Vascular Access (GEMAV), which includes experts from the five scientific societies involved (nephrology [S.E.N.], vascular surgery [SEACV], vascular and interventional radiology [SERAM-SERVEI], infectious diseases [SEIMC] and nephrology nursing [SEDEN]), along with the methodological support of the Cochrane Center, has updated the Guidelines on Vascular Access for Haemodialysis, published in 2005. These guidelines maintain a similar structure, in that they review the evidence without compromising the educational aspects. However, on one hand, they provide an update to methodology development following the guidelines of the GRADE system in order to translate this systematic review of evidence into recommendations that facilitate decision-making in routine clinical practice, and, on the other hand, the guidelines establish quality indicators which make it possible to monitor the quality of healthcare.

Vancomycin dosing in chronic high-flux haemodialysis: a systematic review

The aim of this study was to systematically evaluate whether non-weight-based dosing (non-WBD) or weight-based dosing (WBD) of vancomycin leads to a higher proportion of patients achieving the pharmacokinetic/pharmacodynamic target. Studies from January 1985 to February 2017 were identified through Cochrane, MEDLINE and Embase databases. Those conducted in adults with end-stage renal disease receiving high-flux haemodialysis (HD) and intravenous vancomycin were included. The primary outcome was the proportion of patients with a pre-HD vancomycin concentration of 15-20 mg/L and/or an area under the concentration-time curve/minimum inhibitory concentration (AUC/MIC) ratio ≥400. Of the 3948 studies screened, 5 met the inclusion criteria. The proportion of patients with pre-HD concentrations between 15-20 mg/L were 35% (non-WBD) and 13% (WBD) post-loading dose. During maintenance dosing, the proportion of patients with pre-HD concentrations between 15-20 mg/L were 37% (non-WBD) and 50-67% (WBD). The proportion of pre-HD concentrations <15 mg/L was greater in the non-WBD group post-loading dose but was similar between the non-WBD and WBD group during maintenance dosing. One study reported that all patients had an AUC/MIC ≥ 400 for micro-organisms with an MIC ≤ 1 mg/L for weight-based maintenance dosing. The limited data suggest that WBD may be preferential as there was a smaller proportion of pre-HD concentrations falling below 15 mg/L. However, larger well-designed studies of higher quality are required to provide guidance for vancomycin dosing in the high-flux HD setting. Future research should focus on reporting AUC/MIC ratios and exploring clinical outcomes in this patient population.

Predicting Maintenance Doses of Vancomycin for Hospitalized Patients Undergoing Hemodialysis

BACKGROUND

Methicillin-resistant Staphylococcus aureus is a leading cause of death in patients undergoing hemodialysis. However, controversy exists about the optimal dose of vancomycin that will yield the recommended pre-hemodialysis serum concentration of 15-20 mg/L.

OBJECTIVE

To develop a data-driven model to optimize the accuracy of maintenance dosing of vancomycin for patients undergoing hemodialysis.

METHODS

A prospective observational cohort study was performed with 164 observations obtained from a convenience sample of 63 patients undergoing hemodialysis. All vancomycin doses were given on the floor after completion of a hemodialysis session. Multivariate linear generalized estimating equation analysis was used to examine independent predictors of pre-hemodialysis serum vancomycin concentration.

RESULTS

Pre-hemodialysis serum vancomycin concentration was independently associated with maintenance dose (B = 0.658, p < 0.001), baseline pre-hemodialysis serum concentration of the drug (B = 0.492, p < 0.001), and interdialytic interval (B = -2.133, p < 0.001). According to the best of 4 models that were developed, the maintenance dose of vancomycin required to achieve a pre-hemodialysis serum concentration of 15-20 mg/L, if the baseline serum concentration of the drug was also 15-20 mg/L, was 5.9 mg/kg with interdialytic interval of 48 h and 7.1 mg/kg with interdialytic interval of 72 h. However, if the baseline pre-hemodialysis serum concentration was 10-14.99 mg/L, the required dose increased to 9.2 mg/kg with an interdialytic interval of 48 h and 10.0 mg/kg with an interdialytic interval of 72 h.

CONCLUSIONS

The maintenance dose of vancomycin varied according to baseline pre-hemodialysis serum concentration of the drug and interdialytic interval. The current practice of targeting a pre-hemodialysis concentration of 15-20 mg/L may be difficult to achieve for the majority of patients undergoing hemodialysis.

Vancomycin dosing and monitoring for patients with end-stage renal disease receiving intermittent hemodialysis

PURPOSE

Vancomycin dosing and monitoring algorithms for patients with end-stage renal disease (ESRD) receiving intermittent hemodialysis are reviewed.

SUMMARY

Vancomycin is one of the most commonly administered antimicrobial agents in adult patients with ESRD receiving intermittent hemodialysis. However, despite the availability of many published studies, the single best method of vancomycin administration in this population remains unclear. Many studies evaluating vancomycin dosing in adult patients with ESRD receiving intermittent hemodialysis were limited by a small sample size, inappropriate therapeutic targets, older hemodialysis modalities (e.g., low-flux intermittent hemodialysis), and inconsistencies in the timing of dosing or therapeutic drug monitoring. Pharmacokinetic variables that must be accounted for include a prolonged distribution phase, a redistribution phase and rebound effect after completion of hemodialysis, patient weight, residual renal function, and nonrenal clearance. Optimal vancomycin dosing recommendations are needed, but clinicians should always consider patient-specific variables, the timing of vancomycin administration, the timing of serum vancomycin concentrations, and technical aspects of the dialysis procedure when creating a dosing regimen.

CONCLUSION

Individualized vancomycin dosing regimens and therapeutic drug monitoring are necessary for patients with ESRD receiving intermittent hemodialysis to ensure that goal serum vancomycin levels are reached to adequately treat an infection.