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

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.

Comparison of vancomycin assays in patients undergoing hemodialysis

Vancomycin is a glycopeptide antibiotic mainly excreted by glomerular filtration. Therefore, patients undergoing hemodialysis tend to accumulate its crystalline degradation product, which has been associated with cross-reaction in commercial immunoassays. The aim of this study was to assess the performance of two commercial immunoassays for measuring vancomycin levels in patients undergoing hemodialysis. This method-comparison study enrolled patients undergoing hemodialysis at two hospitals in Porto Alegre, Brazil. Vancomycin serum concentrations measured by Chemiluminescent Microparticle Assay (CMIA) and measured by Kinetic Interaction of Microparticles in Solution (KIMS) were compared with Liquid Chromatography coupled with Tandem Mass Spectrometry (LC-MS/MS). A total of 64 samples from 42 patients and 54 samples from 23 patients were included in CMIA and KIMS groups. Both measurements were highly correlated with LC-MS/MS, with Spearman rank correlation coefficient r = 0.840 (p < 0.001) and r = 0.926 (p < 0.001), respectively. No deviation of linearity was observed (p = 0.81 and p = 0.49, respectively). The mean difference between CMIA and LC-MS/MS was -1.19 μg/mL and between KIMS and LC-MS/MS was -2.28 μg/mL. LC-MS/MS measured levels were, on average, 2.64 % higher than CMIA and 8.81 % higher than KIMS. CMIA and KIMS revealed accurate commercial methods to measure vancomycin serum concentrations in patients undergoing hemodialysis.

Dose optimization and target attainment of vancomycin in children

Vancomycin is a glycopeptide antibiotic that has been adopted in clinical practice to treat gram-positive infections for more than 70 years. Despite vancomycin's long history of therapeutic use, optimal dose adjustments and pharmacokinetic/pharmacodynamic (PK/PD) target attainment in children are still under debate. Therapeutic drug monitoring (TDM) has been widely integrated into pediatric clinical practice to maximize efficacy and safety of vancomycin treatment. Area under the curve (AUC)-guided TDM has been recently recommended instead of trough-only TDM to ensure PK/PD target attainment of AUC0-24h/minimal inhibitory concentration (MIC) > 400 to 600 and minimize acute kidney injury risk. Bayesian forecasting in pediatric patients allows estimation of population PK to accurately predict individual vancomycin concentrations over time, and consequently total vancomycin exposure. AUC-guided TDM for vancomycin, preferably with Bayesian forecasting, is therefore suggested for all pediatric age groups and special pediatric populations. In this review we aim to analyze the current literature on the pediatric use of vancomycin and summarize the current knowledge on dosing optimization for target attainment in special patient populations.

Preparation and application of UPLC silica microsphere stationary phase:A review

In this review, microspheres for ultra-performance liquid chromatography (UPLC) were reviewed in accordance with the literature in recent years. As people's demands for chromatography are becoming more and more sophisticated, the preparation and application of UPLC stationary phases have become the focus of researchers in this field. This new analytical separation science not only maintains the practicality and principle of high-performance liquid chromatography (HPLC), but also improves the step function of chromatographic performance. The review presents the morphology of four types of sub-2 μm silica microspheres that have been used in UPLC, including non-porous silica microspheres (NPSMs), mesoporous silica microspheres (MPSMs), hollow silica microspheres (HSMs) and core-shell silica microspheres (CSSMs). The preparation, pore control and modification methods of different microspheres are introduced in the review, and then the applications of UPLC in drug analysis and separation, environmental monitoring, and separation of macromolecular proteins was presented. Finally, a brief overview of the existing challenges in the preparation of sub-2 μm microspheres, which required further research and development, was given.

Therapeutic drug monitoring of glycopeptide antimicrobials: An overview of liquid chromatography-tandem mass spectrometry methods

Therapeutic drug monitoring (TDM) is a critical clinical tool used to optimize the safety and effectiveness of drugs by measuring their concentration in biological fluids. These fluids are primarily plasma or blood. TDM, together with real-time dosage adjustment, contributes highly to the successful management of glycopeptide antimicrobial therapies. Understanding pharmacokinetic/pharmacodynamic (PK/PD) properties is vital for optimizing antimicrobial therapies, as the efficacy of these therapies depends on both the exposure of the patient to the drug (PK) and pharmacodynamic (PD) parameters such as the in vitro estimated minimum drug concentration that inhibits bacterial growth (MIC). Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) is widely recognized as the gold standard for measuring small molecules, such as antibiotics. This review provides a comprehensive overview of LC-MS/MS methods available for TDM of glycopeptide antibiotics, including vancomycin, teicoplanin, dalbavancin, oritavancin, and telavancin.

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.

Utility of Silver-nanoparticles for Nano-fluorimetric Determination of Vancomycin Hydrochloride in Pharmaceutical Formulation and Biological Fluids: Greenness Assessment

Vancomycin hydrochloride (VANH) is a glycopeptide antibiotic commonly employed in the prophylaxis and therapy of various gram-positive bacterial life-threatening infections. Due to the narrow therapeutic window of VANH, its serum levels should be well-monitored to avoid its toxicity and to optimize its therapy. Herein, an innovative silver-nanoparticles enhanced fluorescence technique was designed for VANH rapid analysis in its pharmaceutical formulation and biological fluids. This technique is based on reinforcement of VANH fluorescence intensity with silver-nanoparticles that were synthesized by a redox reaction between VANH and silver nitrate in NaOH alkaline medium using polyvinylpyrrolidone as a stabilizer. The produced silver-nanoparticles were characterized by using UV-visible spectroscopy where they have an intense absorption maximum at 415 nm and transmission electron microscope (TEM) micrograph where they are spherical in shape with smooth surface morphology and size of 10.74 ± 2.44 nm. The fluorescence intensity was measured at 394 nm after excitation at 259 nm. Under optimum conditions, a good linear relationship was accomplished between the VANH concentration and the fluorescence intensity in a range of (1-36) ng/mL with a limit of detection of 0.29 ng/mL. Greenness assessment was performed using two assessment tools namely; eco-scale scoring and green analytical procedure index revealing excellent greenness of the proposed technique. The proposed technique was validated according to the International Conference on Harmonisation (ICH) recommendations and statistically compared with the reported HPLC method revealing no significant difference concerning accuracy and precision at p = 0.05. The proposed technique depended primarily on water as a cheap and eco-friendly solvent.

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.

Liquid chromatography-tandem mass spectrometry method for quantification of gentamicin and its individual congeners in serum and comparison results with two immunoanalytical methods (fluorescence polarization immunoassay and chemiluminiscent microparticle immunoassay)

BACKGROUND

Total gentamicin is a sum of five congeners C1, C1a, C2, C2a and minor C2b, which differ from each other in their methylation on the purpurosamine ring. Liquid chromatography with mass detection (LC-MS/MS) and specified calibration material enables the concentration of total gentamicin and its individual congeners to be analysed.

METHODS

50 µL serum was precipitated with acetonitrile in the presence of 0.5 mol/L formic acid. A RP BEH C18 1.7 µm 2.1x50 mm column maintained at 30 °C and tobramicin as the internal standard were used. Mass detection was performed in positive electrospray. The gentamicin results were compared with fluorescence polarization immunoassay (FPIA) and chemiluminiscent microparticle immunoassay (CMIA). Passing-Bablock regression analysis and Bland-Altman analysis were used.

RESULTS

Calibration curves for individual gentamicin congeners were linear with correlation coefficients between 0.997 and 0.998. Recovery was 91.6-102.0% and the coefficients of variation 1.4-8.4%. The total gentamicin concentration was compared with immunoassay FPIA (LC-MS_gen = 0.9798xPFIA_gen) and CMIA (LC MS_gen = 0.9835xCMIA_gen) both with significant correlation (p < 0.001).

CONCLUSION

The LC-MS/MS method is fast and precise and can be applied to routine TDM in patients. Comparing it to immunoassays makes it possible to measure concentration of gentamicin congeners, which may be important in the case of their different pharmacokinetics.

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.

Simultaneous separation and determination of vancomycin and its crystalline degradation products in human serum by ultra high performance liquid chromatography tandem mass spectrometry method and its application in therapeutic drug monitoring

A rapid and simple ultra high performance liquid chromatography with tandem mass spectrometry method was developed and validated for the simultaneous separation and determination of vancomycin and its crystalline degradation products in human serum. Vancomycin and two isomers of the degradants were extracted from human serum with a protein precipitation method. The compounds were separated on an Acquity BEH C18 column (2.1 × 50 mm, 1.7 μm) eluted with a gradient mixture of acetonitrile and 0.1% formic acid as the mobile phase. Norvancomycin was used as the internal standard. The linear ranges of vancomycin and two degradant isomers were 1.057-105.7, 0.1437-14.37, and 0.2540-25.40 μg/mL, respectively. The established methods were validated and successfully applied to a therapeutic drug monitoring study of vancomycin in patients with renal insufficiency.