Development and validation of a new ultra-performance liquid chromatographic method for vancomycin assay in serum and its application to therapeutic drug monitoring

High throughput analysis of vancomycin in human plasma by UHPLC-MS/MS

An analytical assay based on ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) technique for absolute quantification of vancomycin in complexed biological matrix was developed in this study. Reversed phase column with gradient elution was chosen for chromatographic separation of vancomycin and internal standard (IS) norancomycin. Sample pretreatment was performed by micro-solid phase extraction (μ-SPE) with Oasis® MAX μElution Plate (I.D., 30 μm). Multiple reaction monitoring (MRM) transition was chosen for monitoring of the analytes. For vancomycin, mass-to-charge ratio (m/z) of the MRM transition was 725.3→144.1; For norvancomycin, m/z of the MRM transition was 718.3→144.2. The running time was 3 minutes for each sample. The UHPLC-MS/MS method showed a good linear relationship (R2≥0.995) in the concentration range of 0.5-100 μg/mL. The intra- and inter-day accuracies (relative error, RE) are within the range of -3.44 %-1.50 % and precisions are between 3.48 % and 10.19 %. μ-SPE could enrich the analytes and decrease the endogenous interferences, thereby improving the selectivity and sensitivity of the method. The analytical assay is selective, accurate and reproducible. The assay was successfully applied to therapeutic drug monitoring of vancomycin in clinical application.

Recent Trends in Therapeutic Drug Monitoring of Peptide Antibiotics

Antimicrobial peptides take a specific position in the field of antibiotics (ATBs), however, from a large number of available molecules only a few of them were approved and are used in clinics. These therapeutic modalities play a crucial role in the management of diseases caused by multidrug-resistant bacterial pathogens and represent the last-line therapy for bacterial infections. Therefore, there is a demand for a rationale use of such ATBs based on optimization of the dosing strategy to minimize the risk of resistance and ensure the sustainable efficacy of the drug in real clinical practice. Therapeutic drug monitoring, as a measurement of drug concentration in the body fluids or tissues, results in the optimization of the patient´s medication and therapy outcome. This strategy is beneficial and could result in tailored therapy for different types of infection and the prolongation of the use and efficacy of ATBs in hospitals. This review paper provides an actual overview of approved antimicrobial peptides used in clinical practice and covers current trends in their analysis by convenient and advanced methodologies used for their identification and/or quantitation in biological matrices for therapeutic drug monitoring purposes. Special emphasis is given to the methods with perspective clinical outcomes.

Preanalytical Stability of 13 Antibiotics in Biological Samples: A Crucial Factor for Therapeutic Drug Monitoring

The stability of antibiotic preanalytical samples is a critical factor in therapeutic drug monitoring (TDM), a practice of undoubted importance for the proper therapeutic use of antibiotics, especially in complex management patients, such as pediatrics. This review aims to analyze the data in the literature regarding the preanalytical stability of some of the antibiotics for which TDM is most frequently requested. The literature regarding the preanalytical stability of amikacin, ampicillin, cefepime, ceftazidime, ciprofloxacin, daptomycin, gentamicin, levofloxacin, linezolid, meropenem, piperacillin, teicoplanin, and vancomycin in plasma, serum, whole blood, and dried blood/plasma spot samples was analyzed. Various storage temperatures (room temperature, 4 °C, -20 °C, and -80 °C) and various storage times (from 1 h up to 12 months) as well as subjecting to multiple freeze-thaw cycles were considered. The collected data showed that the non-beta-lactam antibiotics analyzed were generally stable under the normal storage conditions used in analytical laboratories. Beta-lactam antibiotics have more pronounced instability, particularly meropenem, piperacillin, cefepime, and ceftazidime. For this class of antibiotics, we suggest that storage at room temperature should be limited to a maximum of 4 h, storage at 2-8 °C should be limited to a maximum of 24 h, and storage at -20 °C should be limited to a maximum of 7 days; while, for longer storage, freezing at -80 °C is suggested.

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.

Development, validation, and application of an UPLC-MS/MS method for vancomycin, norvancomycin, methotrexate, paclitaxel, and imatinib analysis in human plasma

Background

Vancomycin, norvancomycin, methotrexate, paclitaxel, and imatinib are five commonly used drugs which are all recommended to therapeutic drug monitoring in clinical settings. However, the blood concentration monitoring of these drugs and the interpretations of the test results are limited to some extent due to the differences of testing instruments and testing methods.

Methods

We established an ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) method for simultaneous quantification of vancomycin, norvancomycin, methotrexate, paclitaxel, and imatinib in human plasma. The method was validated according to the guideline for bioanalytical method validation and applied in clinical therapy.

Results

The calibration ranges of vancomycin, norvancomycin, methotrexate, paclitaxel, and imatinib were 0.5–100 μg/mL, 0.5–100 μg/mL, 5–1000 ng/mL, 10–2000 ng/mL, and 5–500 ng/mL, respectively. Inaccuracy and imprecision of every drug were less than 15%. The internal standard normalized recovery rates of vancomycin and norvancomycin were about 45%, while which of methotrexate, paclitaxel, and imatinib were almost 100%. No obvious carryover effect was observed. Samples were stable for at least 24 h in the automatic sampler, 72 h at 4°C, and 1 week in −80°C. There were no differences of concentrations between plasma and serum for the five drugs. Moreover, there were positive correlations between methotrexate and vancomycin concentrations and creatinine, as well as positive correlation between imatinib concentration and age of the patient.

Conclusions

The UPLC-MS/MS method was competent for the simultaneous monitoring of vancomycin, norvancomycin, methotrexate, paclitaxel, and imatinib because of its short analysis time, high specificity, and accuracy.

Degradation of vancomycin in external quality assessment samples is a factor to underestimate its concentration

Aim: To compare the difference between the measured and target values in vancomycin external quality assessment (EQA) samples and to investigate the factors for underestimating its concentration. Materials & methods: A retrospective analysis of 195 international vancomycin EQA results was performed. Deviations of the concentrations determined by TDx fluorescence polarization immunoassay (FPIA), Axsym FPIA and Architect chemiluminescence microparticle immunoassay (CMIA) method were -2.43, -16.28 and -10.53%, respectively. Chromatographic peaks of the crystalling degradation products appeared in samples with large deviations. Vancomycin were degraded after long-term transporting and high temperature. Conclusion: Vancomycin concentrations measured by Axsym FPIA and Architect CMIA methods were likely to be underestimated. Long-term transporting resulted in low EQA results, suggesting that establishing a local EQA system for vancomycin is essential.

An UHPLC-UV Method for the Determination of Vancomycin in Human Serum

Objective:

To develop a rapid ultra-performance liquid chromatographic (UHPLC)-UV method for vancomycin determination in human serum for therapeutic drug monitoring (TDM).

Methods:

Human serum samples were precipitated with 10% perchloric acid, and the supernatant after centrifugation was analyzed on an ACQUITY UHPLC BEH C18 column (2.1 × 50mm, 1.7 μm) via gradient elution with a flow rate at 0.3 mL/min. The mobile phase consisted of acetonitrile and 0.005M KH2PO4 buffer (containing 0.1% triethylamine, pH 3.4). The detection wavelength was set at 210 nm, and the column temperature was set at 40°C. The total runtime was 6.0 min per analysis.

Results:

After comprehensive validation, the method was applied to determine the concentration of vancomycin in human serum. The chromatographic peaks of vancomycin and internal standard were not interfered by endogenous matrices. The Retention Time (RT) of vancomycin was 1.91 min, while the internal standard was 1.58 min. The good linearity range of vancomycin concentration was 2.5-120 μg/mL (R2>0.999). The lower Limit of Quantitation (LLOQ) was 2.5 μg/mL. The precision at three Quality Control (QC) levels (including LLOQ) was restricted within 85-115%. The extraction recovery rate of QC samples (4.0, 20.0, and 60.0 μg/mL) were 101.16%, 97.70%, and 94.90%, respectively. Inter- and intra-day precision was less than 8% (RSD). Stability tests under different storage conditions were satisfactory. In patients, the concentration of vancomycin ranged from 7.30 to 89.12 μg/mL determined by the fully validated method.

Conclusion:

The rapid sample pre-treatment procedures and short analysis time made this UHPLC-UV method suitable for therapeutic drug monitoring (TDM) of vancomycin.

A systematic review on chromatography-based method validation for quantification of vancomycin in biological matrices

A fully validated bioanalytical methods are prerequisite for pharmacokinetic and bioequivalence studies as well as for therapeutic drug monitoring. Due to high pharmacokinetic variability and narrow therapeutic index, vancomycin requires reliable quantification methods for therapeutic drug monitoring. To identify published chromatographic based bioanalytical methods for vancomycin in current systematic review, PubMed and ScienceDirect databases were searched. The selected records were evaluated against the method validation criteria derived from international guidelines for critical assessment. The major deficiencies were identified in method validation parameters specifically for accuracy, precision and number of calibration and validation standards, which compromised the reliability of the validated bioanalytical methods. The systematic review enacts to adapt the recommended international guidelines for suggested validation parameters to make bioanalysis reliable.

A simple and validated HPLC method for vancomycin assay in plasma samples: the necessity of TDM center development in Southern Iran

BACKGROUND AND PURPOSE

Vancomycin is a glycopeptide antibiotic which is the drug of choice against methicillin-resistant Staphylococcus aureus. It has a narrow therapeutic index, and thus therapeutic drug monitoring (TDM), and clinical pharmacokinetic assessment are necessary in order to prevent adverse drug reactions such as nephrotoxicity. In this study, we aimed to develop a simple and validated HPLC method for vancomycin assay in order to establish a TDM center for patients admitted to the ICU of Nemazee Hospital in southern Iran.

EXPERIMENTAL APPROACH

In this study, a brief review of different parameters and variables which could affect the sensitivity, selectivity of the validated HPLC method for vancomycin determination were considered. According to the previous studies a simple, fast, and the relatively low-cost method was established for vancomycin determination in plasma samples.

FINDINGS/RESULTS

The developed HPLC assay indicated a calibration curve with R-square of > 0.999, acceptable selectivity, the accuracy of 90-105%, CV% of less than 15%, the limit of quantification of 1 μg/mL, and limit of detection of 300 ng/mL. Vancomycin trough level, the area under the curve, renal clearance, the volume of distribution, and elimination constant were measured in patients using this validated method.

CONCLUSION AND IMPLICATIONS

Validated method for assay of vancomycin plasma levels was used to quantify vancomycin levels of four patients who were admitted to the ICU of Nemazee Hospital. According to the results, two of these patients showed lower levels than recommended therapeutic purposes while one of them showed a toxic level. According to the results, the TDM assessment of vancomycin is strongly recommended for patients who are hospitalized in ICU.

An ultra-performance liquid chromatography–tandem mass spectrometry method to quantify vancomycin in human serum by minimizing the degradation product and matrix interference

Aim: This study aimed to develop and validate a method for better therapeutic monitoring of vancomycin serum concentration. Methods & results: An ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method was developed and validated to minimize the interference of crystalline degradation product and matrix. It was compared with chemiluminescence microparticle immunoassay (CMIA) and ultra-performance liquid chromatography with ultraviolet detection (UPLC-UV) in the performance of testing normal, on-dialysis and hemolytic serum samples. For on-dialysis samples, a moderate correlation (r = 0.534) was observed between UPLC-UV and UPLC–MS/MS. In testing hemolytic samples, ten (10/85, 11.8%) samples were overestimated by CMIA method. Conclusion: Vancomycin concentration determined by CMIA, UPLC-UV was more affected by various panels of serum samples than UPLC–MS/MS assay, suggesting that UPLC–MS/MS is a more reliable and promising tool for clinical vancomycin therapeutic drug monitoring.

A Rapid and Simple HPLC Method for Therapeutic Monitoring of Vancomycin

Therapeutic monitoring of the antibiotic vancomycin is important to achieve specific plasma concentration and prevent toxic effects. Several assays have been described for vancomycin determination in clinical practice, but high-performance liquid chromatography is still considered the gold standard for the quantification of vancomycin. In this study, we developed a new and rapid high-performance liquid chromatography method requiring 50 μL of plasma for the quantification of vancomycin. Acetonitrile was used for processing plasma by protein precipitation (1:2.5). Isocratic chromatographic analysis was carried out on a C18 silica-based (2.7 μm) column with the mobile phase containing 20 mM ammonium acetate/formic acid buffer (pH 4.0):methanol 88:12 (v/v). A diode array detector was used for UV detection at 240 nm. This method was validated according to the Brazilian Health Surveillance Agency legislation and International Conference on Harmonization guidelines. The measurement range was 1-100 μg/mL, analysis time was 8 min, and intermediate precision was <12%, supporting the present method as a fast, simple, and effective alternative for therapeutic monitoring of vancomycin.

An LC-MS/MS method to determine vancomycin in plasma (total and unbound), urine and renal replacement therapy effluent

AIM

Critical illness and medical interventions, such as renal replacement therapy, can cause changes to vancomycin pharmacokinetics and lead to suboptimal dosing. To comprehensively characterize vancomycin pharmacokinetic a method must measure vancomycin in a range of clinical matrices.

RESULTS

A LC-MS/MS method was developed using hydrophilic interaction liquid chromatography and microsample volumes, where possible. For all matrices, the linear concentration range was 1-100 μg/ml, interassay accuracy and precision was within 15%, and recovery above 80%. No matrix effects were observed. Calibration equivalence may be applied for some matrix combinations.

CONCLUSION

A method for the analysis of vancomycin in plasma (total, unbound), urine and renal replacement therapy effluent, suitable for use in any patient pharmacokinetic study, has been developed and validated.

Development and validation of an HPLC method for the determination of vancomycin in human plasma and its comparison with an immunoassay (PETINIA)

Vancomycin (VAN) is among those antibiotics for which therapeutic drug monitoring is highly recommended. For this purpose a reliable method with small sample volume was required for quantification of VAN in human plasma. Therefore, a selective and sensitive method of high performance liquid chromatography was developed and validated. The separation was carried out isocratically by using a mobile phase NH₄H₂PO₄ (50 mM, pH 2.2)–acetonitrile (88:12, v/v) at a flow rate of 0.36 mL/min on a nucleodur C18 column (125 mm × 4.6 mm, 5 µm) with UV detection at 205 nm. Sample preparation was done by deproteination of plasma with 70 % perchloric acid and a liquid/liquid extraction. Validation was performed according to the European Medicines Agency guideline. The method showed linearity over the range of 0.25–60 mg/L with a coefficient of determination r² ≥ 0.999 and a lower limit of quantification of 0.25 mg/L. No interference was observed in blank plasma samples at the retention time of VAN. The percentage relative recovery and coefficient of variation (CV%) values for accuracy and precision were within the acceptable limits. Stability was proved at room temperature for 24 h, after repeated freeze and thaw cycles and storage at −20 °C for 3 months. A good correlation was observed (r = 0.947) by comparing with the results of an immunoassay (PETINIA, Siemens) in 289 samples. In conclusion the method proved simple, sensitive and cost effective for quantification of VAN in human plasma.