Liquid chromatographic-electrospray tandem mass spectrometric determination of clarithromycin in human plasma

Rapid Characterization of Undeclared Pharmaceuticals in Herbal Preparations by Ambient Ionization Mass Spectrometry for Emergency Care

In Asia, some herbal preparations have been found to be adulterated with undeclared synthetic medicines to increase their therapeutic efficiency. Many of these adulterants were found to be toxic when overdosed and have been documented to bring about severe, even life-threatening acute poisoning events. The objective of this study is to develop a rapid and sensitive ambient ionization mass spectrometric platform to characterize the undeclared toxic adulterated ingredients in herbal preparations. Several common adulterants were spiked into different herbal preparations and human sera to simulate the clinical conditions of acute poisoning. They were then sampled with a metallic probe and analyzed by the thermal desorption-electrospray ionization mass spectrometry. The experimental parameters including sensitivity, specificity, accuracy, and turnaround time were prudently optimized in this study. Since tedious and time-consuming pretreatment of the sample is unnecessary, the toxic adulterants could be characterized within 60 s. The results can help emergency physicians to make clinical judgments and prescribe appropriate antidotes or supportive treatment in a time-sensitive manner.

Determination of tacrolimus in human whole blood in kidney transplant recipients using a rapid and specific LC-MS/MS method

OBJECTIVE

To develop and validate an LC-M/SMS method for the determination of tacrolimus in human whole blood.

METHOD

The LC-MS/MS method for the determination of tacrolimus in whole blood was developed and validated according to the guidelines. Concentrations of TAC in 100 kidney transplant patients measured by LC-MS/MS were compared with CMIA using correlation analysis and Bland-Altman plots.

RESULTS

The method had a total chromatographic run time of 5 min. The calibration curves were linear over the range of 0.5-100.0 ng/mL with a lower limit of quantification of 1 ng/mL. The intra- and interday accuracy was within the range of 93.3%-109.2% and 96.0%-108.4%, respectively, with precision ranging from 0.8 to 9.4%. The mean extraction recoveries of TAC ranged from 102.6 to 107.8%. The mean concentrations of TAC in whole blood of kidney transplant patients measured by the two assays were different at 1, 3 months and all time points (p < 0.001), but no significant difference was observed at 6 months (p = 0.094). The correlation of data was good with the correlation coefficients (r2 ) of 0.7581, 0.8811, 0.8777, and 0.8077, respectively. Passing-Bablok regression analysis demonstrated good correlations with r2 values higher than 0.88 between TAC levels measured by LC-MS/MS and CMIA. Using Bland-Altman plots yielded average biases of 1.29, 0.79, 0.11, and 0.65 ng/mL at 1, 3, and 6 months and all time points.

CONCLUSION

The LC-MS/MS method was validated for the accurate determination of TAC in human whole blood. The comparison of tacrolimus concentrations measured by the LC-MS/MS with CMIA showed a good correlation and agreement of two methods, suggesting LC-MS/MS should be used routinely to monitor TAC concentrations in kidney transplant patients.

Thermal desorption ambient ionization mass spectrometry for emergency toxicology

In the emergency department, it is important to rapidly identify the toxic substances that have led to acute poisoning because different toxicants or toxins cause poisoning through different mechanisms, requiring disparate therapeutic strategies and precautions against contraindicating actions, and diverse directions of clinical course monitoring and prediction of prognosis. Ambient ionization mass spectrometry, a state-of-the-art technology, has been proved to be a fast, accurate, and user-friendly tool for rapidly identifying toxicants like residual pesticides on fruits and vegetables. In view of this, developing an analytical platform that explores the application of such a cutting-edge technology in a novel direction has been initiated a research program, namely, the rapid identification of toxic substances which might have caused acute poisoning in patients who visit the emergency department and requires an accurate diagnosis for correct clinical decision-making to bring about corresponding data-guided management. This review includes (i) a narrative account of the breakthrough in emergency toxicology brought about by the advent of ambient ionization mass spectrometry and (ii) a thorough discussion about the clinical implications and technical limitations of such a promising innovation for promoting toxicological tests from tier two-level to tier one level.

Pharmacokinetic study of clarithromycin in human breast milk by UPLC-MS/MS

This study aimed to develop a validated UPLC-MS/MS method for pharmacokinetic analysis of clarithromycin in human breast milk. For sample preparation, proteins precipitated with methanol and azithromycin were used as internal standards. Clarithromycin and azithromycin detection was achieved using electrospray ionization in positive mode. The chromatographic separation time was 5 min. The lower limit of quantification was 50 ng/mL. The calibration curve of clarithromycin was 50-4000 ng/mL, with a correlation coefficient> 0.99. The method was successfully applied to determine clarithromycin levels in breast milk obtained from a lactating mother after oral administration of a single tablet containing 500 mg of clarithromycin. The maximum human breast milk concentration (C_max) was 3660 ng/mL, the time to reach the maximum concentration (t_max) was 2.5 h, and the area under curve (AUC_0-24) was 18450 ng h/mL. The present study provides a novel UPLC-MS/MS method for pharmacokinetic analysis of clarithromycin in breast milk.

Method Development of Clarithromycin by Chromophore Addition through Chemical Derivatization

Introduction:

Clarithromycin is a macrolide antibiotic that is active against a variety of microorganisms. It is widely used in the local and international market in different pharmaceutical dosage forms. However, its chemical structure lacks a chromophore and hence it has a low absorption and this makes it more difficult to be detected at low concentrations. In this research project we proposed an easy and feasible chemical derivatization of clarithromycin to introduce a chromophore in order to increase its absorptivity at low concentration using a simple reverse phase HPLC analytical method.

Methodology:

Chemical derivatization of clarithromycin involved an introduction of benzoyl groups as a chromophore through esterification reaction. A reverse phase analytical HPLC method was developed to quantify clarithromycin at a very low concentration compared to the standard official pharmacopeia.

Results:

Clarithromycin was successfully derivatized and a hyperchromic and bathochromic shift to UV absorption lambda max (λmax) was achieved (λmax = 245nm.) A successful chromatographic separation was obtained using reverse phase HPLC chromatography. The developed method was capable of detecting and quantifying clarithromycin at very low concentration. The Limit of Quantification (LOD) and Limit of Quantification (LOQ) was found to be 2*10-8 mg/ml and 2*10-6 mg/ml respectively.

Conclusion:

Clarithromycin was successfully derivatized to a chromophore containing molecule. The developed reverse phase HPLC method is capable to detect and quantify clarithromycin at a very low concentration. The method can successfully quantify clarithromycine when present in low concentration such as in biological and enviromental samples.

Novel Eco-friendly HPLC Methods Using Refractive Index Detector for Analysis of Three Veterinary Antibiotics in Pharmaceutical Formulations and Rat Plasma

Antibiotic resistance increases the human mortality rate nowadays. The main purpose of the present study was to develop green reversed-phase high-performance liquid chromatography (RP-HPLC) methods with a refractive index detector for the assay of the three veterinary antibiotics (VAs), i.e., maduramicin ammonium (MA), apramycin sulfate (AS) and clarithromycin (CLA) in pharmaceutical dosage forms and spiked rat plasma. The method utilized isocratic elution using an ODP-40 C18 column, the flow rate was set at 1.0 mL/min and negative polar signals. The linearity ranges were 3.0-18.0 μg/mL for MA, 1.5-4.0 μg/mL for AS and 0.5 to 3.0 μg/mL for CLA, respectively. Liquid-liquid extraction (LLE) procedure was optimized in plasma samples. The recoveries percentages were 85.4, 81.2 and 88.8 correspondingly, in rat plasma. However, the drugs extraction by protein precipitation method yields very poor recoveries (around 50%). The new HPLC- refractive index (RI) methods are better than the previously reported HPLC-ultra violet methods in terms of greenness and simplicity of procedures. Moreover, the previously reported LC-MS methods lack the simplicity and availability of such expensive techniques in Quality control (QC) labs. The novelty of this research is the use of refractive index detector for the first time for VAs analysis.

Bioanalysis of antitubercular drugs using liquid chromatography

Tuberculosis is a life threatening disease and second to HIV in terms of deaths due to infectious diseases. Drug resistance development of the first-line drugs is a major concern in the treatment of this disease. There is no comprehensive and critical review in the literature of the bioanalytical methods for the determination of anti-tubercular agents from last two decades. This work offers a detailed account on the liquid chromatographic methods reported in the literature for the estimation of various anti-tubercular drugs. Major emphasis is given to sample preparation process, sensitivity of method, chromatographic separation conditions and detection systems used in their bioanalysis.

Rapid point-of-care identification of oral medications in gastric lavage content by ambient mass spectrometry in the emergency room

RATIONALE

Acute poisoning should be handled with high efficiency in order to minimize morbidity and mortality in the emergency room. Unfortunately, history-taking and physical examination are not always reliable. Mis-swallowing of oral medications is common in the pediatric group. This study aimed at developing a rapid point-of-care ambient mass spectrometric method for the early identification of ingested oral medications in gastric lavage content.

METHODS

Four different types of oral medications that are most commonly mis-swallowed by children were diluted to different concentrations. Each of these chemical solutions was mixed with human gastric lavage content. A direct metallic sampling probe was dipped into the solution. It was then inserted promptly into the thermal desorption electrospray ionization source to carry out ionization and subsequent mass spectrometric analysis of the medications. The corresponding compounds were identified through matching of the obtained mass spectrometric data with those provided by well-established databases.

RESULTS

Since no pretreatment of the specimen was required, the sampling step, and the subsequent thermal desorption electrospray ionization and mass spectrometric detection of the medications were completed within 30 s. Mass spectra were obtained for four different kinds of oral medication. The limit-of-detection of the four tested oral medications in gastric lavage content is at sub-ppm level, which is sensitive enough for emergency medicine applications since the quantities of medications ingested by pediatric patients are usually much higher.

CONCLUSIONS

Thermal desorption electrospray ionization mass spectrometry, with informational support provided by an online mass spectral database, allows for early point-of-care identification of mis-swallowed oral medications in the evacuated gastric lavage contents obtained from gastric lavage of patients in the emergency room, and it is promising in providing important toxicological information to ensure the appropriateness of the subsequent medical management. Copyright © 2016 John Wiley & Sons, Ltd.

Novel microwell assay with high throughput and minimum consumption for organic solvents in the charge transfer-based spectrophotometric determination of clarithromycin in pharmaceutical formulations

BACKGROUND

Clarithromycin (CLM) is a semi-synthetic macrolide antibiotic with a broad antibacterial spectrum. It has a potent activity against Myc. Pneumonia, Legionella Spp., H. Influenza, and Mor. Catarrhalis. It is also used for prevention and treatment of disseminated M. Avium infections in patients with AIDS. The therapeutic importance and wide use of CLM promotes the growing interest in developing proper methods for its determination in bulk and pharmaceutical formulations.

RESULTS

The present study describes the development and validation of a novel assay that can increase the throughput and reduce the consumption of organic solvents in the charge transfer (CT)-based spectrophotometric determination of CLM. In this assay, the CT reaction between CLM as n-electron donor and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as a π-electron acceptor was performed in the 96-microwells of an assay plate. The color signals of the CT complex were measured at 450 nm by microwell-plate absorbance reader. The linear range of the assay was 20-850 μg mL-1. The limits of detection and quantitation were 15.5 and 51.2 μg mL-1, respectively. The proposed assay gave very high precisions; the relative standard deviation (RSD) values did not exceed 1.82%.

CONCLUSIONS

The assay described herein has a high throughput property that facilitates the processing of large number of samples in a reasonable time. As well, it consumes minimum volumes of organic solvents, thus it significantly reduces the exposures of the analysts to the toxic effects of organic solvents, and reduce the analysis cost by 50-folds. The results demonstrated that the proposed assay has great practical value in the routine analysis of CLM in quality control laboratories.

Analysis of macrolide antibiotics, using liquid chromatography-mass spectrometry, in food, biological and environmental matrices

Macrolides are a group of antibiotics that have been widely used in human medical and veterinary practices. Analysis of macrolides and related compounds in food, biological, and environmental matrices continue to be the focus of scientists for the reasons of food safety, pharmacokinetic studies, and environmental concerns. This article presents an overview on the primary biological properties of macrolides and their associated analytical issues, including extraction, liquid chromatography-mass spectrometry (LC-MS), method validation, and measurement uncertainty. The main techniques that have been used to extract macrolides from various matrices are solid-phase extraction and liquid-liquid extraction. Conventional liquid chromatography (LC) with C18 columns plays a dominant role for the determination of macrolides, whereas ultra-performance liquid chromatography (UPLC) along with sub-2 microm particle C18 columns reduces run time and improves sensitivity. Mass spectrometry (MS), serving as a universal detection technique, has replaced ultraviolet (UV), fluorometric, and electrochemical detection for multi-macrolide analysis. The triple-quadrupole (QqQ), quadrupole ion trap (QIT), triple-quadrupole linear ion trap, time-of-flight (TOF), and quadrupole time-of-flight (QqTOF) mass spectrometers are current choices for the determination of macrolides, including quantification, confirmation, identification of their degradation products or metabolites, and structural elucidation. LC or UPLC coupled to a triple-quadrupole mass spectrometer operated in the multiple-reaction monitoring (MRM) mode (LC/MS/MS) is the first choice for quantification. UPLC-TOF or UPLC-QqTOF has been recognized as an emerging technique for accurate mass measurement and unequivocal identification of macrolides and their related compounds.

Simplified method for determination of clarithromycin in human plasma using protein precipitation in a 96-well format and liquid chromatography-tandem mass spectrometry

A simplified method to determine clarithromycin concentrations in human plasma using protein precipitation in a 96-well plate and liquid chromatography-tandem mass spectrometry was developed and validated. Plasma proteins were precipitated with acetonitrile and roxithromycin was used as the internal standard. After vortex mixing and centrifugation, the supernatants were directly injected onto a Phenomenex Luna Phenyl-Hexyl column (50 mm x 2.0 mm ID, 3 microm). The mobile phase consisted of water and methanol (30:70, v/v) containing 0.1% formic acid and 5mM ammonium acetate. The flow rate was 0.22 mL/min and the total run time (injection to injection) was less than 3 min. Detection of the analytes was achieved using positive ion electrospray tandem mass spectrometry in selected reaction monitoring (SRM) mode. The linear standard curve ranged from 100 to 5000 ng/mL and the precision and accuracy (inter- and intra-run) were within 7.9% and 4.9%, respectively. The method was successfully used to determine clarithromycin concentrations in human plasma samples obtained from healthy subjects who were given clarithromycin 500 mg for 3 days. The method is rapid, simple, precise and directly applicable to clarithromycin pharmacokinetic studies.