Current Status of Vancomycin Analytical Methods

Prediction of Area Under the Curve from Urinary Vancomycin Concentrations Measured Using a Simple Method

Therapeutic drug monitoring (TDM) is recommended during vancomycin (VCM) administration to adjust the dosage such that the area under the curve (AUC) remains between 400 and 600 µg·h/mL (minimum inhibitory concentration = 1 µg/mL). However, measuring the AUC requires frequent blood sampling, which increases the burden of added time and cost for testing on both patients and healthcare personnel. Therefore, we aimed to address these issues by developing a simple and rapid method for measuring urinary VCM levels using solid-phase extraction and fluorescence spectrometry. The developed method had a quantification range of 100-2,000 µg/mL, with an accuracy of 100.0%-108.5% for concentrations of 200, 1,000, and 2,000 µg/mL. The intra- and inter-day relative standard deviations were below 3.39% and 4.48%, respectively. Furthermore, to predict the AUC from urinary VCM concentrations, we calculated the slope of the urinary concentrations at 7-12 h post-VCM administration in six patients. The slope for one patient differed significantly from that for the others, and the AUC was obtained using practical AUC-guided TDM for vancomycin (PAT) ver. 3.0c for the patient whose value deviated from the recommended range. A negative correlation was observed between the slope and AUC, with a correlation coefficient of 0.65, suggesting the potential for predicting AUC from urinary concentration trends. The use of urine samples, which can be easily obtained, for VCM dose adjustment is expected to contribute to providing more appropriate drug therapy to patients and reduce the burden on healthcare professionals.

Therapeutic Monitoring of Vancomycin Implemented by Eremomycin ELISA

BACKGROUND/OBJECTIVES

Due to a narrow therapeutic window, side-effects, toxicities, and individual pharmacokinetics (PK) variability, WHO classifies vancomycin (VCM) as a "watch antibiotic" whose use should be monitored to improve clinical effectiveness. Availability and ease of use have made the immunoassay technique the basic tool for the therapeutic drug monitoring (TDM) of VCM concentrations.

METHODS

The present study describes the development of a TDM tool for VCM based on anti-eremomycin (ERM) antibody enzyme-linked immunosorbent assay (ELISA).

RESULTS

The optimized assay format based on coating a BSA-VCM conjugate allowed for the equal recognition of both VCM and ERM (100 and 104%) and was not influenced by concomitant antibiotics. Among the sample pretreatments studied, acetonitrile deproteinization was preferred to effectively remove the most likely matrix interferences and to provide 75-96% VCM recovery in the range of 3-30 mg/L, ensuring reliable determination of the key PK parameter, Ctrough. Higher peak concentrations were measured in more diluted samples. Several inflammatory indices, biochemical markers, and key proteins significantly different from normal in critically ill patients were investigated as assay interferers and were found not to interfere with VCM analysis. Serum samples (n = 108) from patients (n = 4) with extensive burn injuries treated with combined antibiotic therapy were analyzed for VCM using the developed assay and confirmed by LC-MS/MS, demonstrating good agreement.

CONCLUSIONS

The approach used shows that the same analytical instrument is suitable for measuring structurally related analytes and is fully adequate for their therapeutic monitoring. Suboptimal exposure based on Ctrough values obtained with standard dosing regimens supports the use of TDM in these patients.

Review of Analytical Methods for Evaluating Azithromycin in the Context of Green Analytical Chemistry

BACKGROUND

Azithromycin (AZT) is an antimicrobial available in different pharmaceutical forms and many people can have access to this medicine. Therefore, the existence of adequate and reliable analytical methods for evaluating the quality of AZT and AZT-based products is essential.

OBJECTIVE/METHODS

The purpose of this review is to discuss the analytical methods for evaluating AZT present in the literature and official compendia in the context of Green Analytical Chemistry (GAC).

RESULTS

Among the methods found in the literature for evaluating AZT, the most used method is HPLC (62%) followed by TLC (14%) and the microbiological method by agar diffusion (14%). Even pharmacopoeias recommend the analysis of AZT by HPLC or agar diffusion. Acetonitrile and methanol account for 35% of the most used solvents in the analyses, followed by buffer.

CONCLUSION

AZT lacks analytical methods in the context of GAC. Both physical-chemical and microbiological methods can contemplate the environmentally friendly way to analyze AZT and AZT-based products, depending only on the chosen conditions. Ethanol, purified water, acetic acid instead of methanol, acetonitrile, buffer, formic acid in the physical-chemical methods are excellent alternatives. However, in the microbiological method, turbidimetry is a great option instead of agar diffusion.

Tools to Evaluate the Eco-efficiency of Analytical Methods in the Context of Green and White Analytical Chemistry: A Review

BACKGROUND

The release of a product in the consumer market requires an analysis by quality control. This sector makes use of reliable analytical methods, by high performance liquid chromatography (HPLC), spectrophotometry in the ultraviolet and visible regions (UV-Vis), spectrophotometry in the infrared region (IR) or thin layer chromatography (TLC), for example, to reach a result. The analysis conditions of most of these analytical methods currently still use toxic reagents, generate a greater amount of waste, sample preparation has more steps, the need for instrumentation and consumables in greater quantity, generating a cost and impact on health and the environment greater than if there were adoption of the Green Analytical Chemistry (GAC) and the White Analytical Chemistry (WAC).

OBJECTIVE/METHODS

The objective of this review is to show the relationship of analytical choices for current pharmaceutical analyzes with the GAC and the WAC.

RESULTS

Analytical methods can be evaluated for greenness and whiteness using tools such as the National Environmental Method Index (NEMI), Eco-Scale Assessment (ESA), Analytical Greenness Metric (AGREE) and Green Analytical Procedure Index (GAPI).

CONCLUSION

The use of NEMI, ESA, AGREE and GAPI tools brings the objective evidence needed to discuss the greenness and whiteness of an analytical method, leaving the subjective level. Furthermore, semi or quantitative data facilitate the choice of an analytical method and its conditions, when the target is the concern with eco-efficiency.

An Overview of Analytical Methodologies for Determination of Vancomycin in Human Plasma

Vancomycin is regarded as the last resort of defense for a wide range of infections due to drug resistance and toxicity. The detection of vancomycin in plasma has always aroused particular concern because the performance of the assay affects the clinical treatment outcome. This article reviews various methods for vancomycin detection in human plasma and analyzes the advantages and disadvantages of each technique. Immunoassay has been the first choice for vancomycin concentration monitoring due to its simplicity and practicality, occasionally interfered with by other substances. Chromatographic methods have mainly been used for scientific research due to operational complexity and the particular requirement of the instrument. However, the advantages of a small amount of sample needed, high sensitivity, and specificity makes chromatography irreplaceable. Other methods are less commonly used in clinical applications because of the operational feasibility, clinical application, contamination, etc. Simplicity, good performance, economy, and environmental friendliness have been points of laboratory methodological concern. Unfortunately, no one method has met all of the elements so far.

A Vancomycin HPLC Assay for Use in Gut Microbiome Research

The human microbiome project has revolutionized our understanding of the interaction between commensal microbes and human health. By far, the biggest perturbation of the microbiome involves use of broad-spectrum antibiotics excreted in the gut. Thus, pharmacodynamics of microbiome changes in relation to drug exposure pharmacokinetics is an emerging field. However, reproducibility studies are necessary to develop the field. A simple and fast high-performance liquid chromatography-photodiode array detector (HPLC) method was validated for quantitative fecal vancomycin analysis. Reproducibility of results were tested based on sample storage time, homogeneity of antibiotic within stool, and concentration consistency after lyophilization. The HPLC method enabled the complete elution of vancomycin within ~4.2 min on the reversed-phase C18 column under the isocratic elution mode, with excellent recovery (85% to 110%) over a 4-log, quantitative range (0.4-100 μg/mL). Relative standard derivations (RSD) of intra-day and inter-day results ranged from 0.4% to 5.4%. Using sample stool aliquots of various weights consistently demonstrated similar vancomycin concentrations (mean RSD: 6%; range: 2-16%). After correcting for water concentrations, vancomycin concentrations obtained after lyophilization were similar to the concentrations obtained from the original samples (RSD less than 10%). These methodologies establish sample condition standards for a quantitative HPLC to enable vancomycin pharmacokinetic studies with the human microbiome. IMPORTANCE Research on antibiotic effect on the gut microbiome is an emerging field with standardization of research methods needed. In this study, a simple and fast high-performance liquid chromatography method was validated for quantitative fecal vancomycin analysis. Reproducibility of results were tested to standardize storage time, homogeneity of antibiotic within stool, and concentration consistency after lyophilization. These methodologies establish sample condition standards for a quantitative HPLC to enable vancomycin pharmacokinetic studies with the human microbiome.

Turbidimetric Method: A Multi-Advantageous Option for Assessing the Potency of Ceftriaxone Sodium in Powder for Injection

BACKGROUND

Ceftriaxone sodium, an antimicrobial used in parenteral form, does not have a microbiological method by turbidimetry described in the literature. For drugs from antimicrobial class, the existence of a microbiological method for assessing their potency is essential. Not only are the results from the physical-chemical methods enough, but microbiological analyzes are also necessary.

OBJECTIVE AND METHODS

Thus, this paper reports the development and validation of an efficient, accurate, reproducible, fast, and low-cost microbiological assay by turbidimetry to quantify ceftriaxone sodium in powder for injection. Water was used as the diluent to prepare the ceftriaxone solutions. BHI broth as used as culture media for the growth of the S. aureus ATCC 6538 at 9%.

RESULTS

The method was linear in the range of 100-196 µg/mL, selective against the sample adjuvants and the forced degradation test, precise (intraday RSD 4.53%, interday RSD 3.85% and between analysts tcalculated 0.14 < 2.23 tcritical), accurate with recovery of 100.33% and robust against minor changes in the volume of culture medium used, wavelength, incubation time, and inoculum concentration.

CONCLUSIONS AND HIGHLIGHTS

The turbidimetric method developed in this paper is a convenient and valuable alternative to the routine quality control of ceftriaxone sodium in powder for injection, since it allows a reliable quantification and can be used to complement the physical-chemical analysis.