Central composite design driven optimization of sustainable stability indicating HPLC method for the determination of Tigecycline and greenness assessment

Background: Tigecycline (TGC) is a recently developed antibiotic to battle resistant bacteria. The procedures outlined in the literature for analyzing TGC involve chemical solvents that could be hazardous. Therefore, this study aimed to create a sustainable and stable HPLC technique for quantifying Tigecycline in lyophilized powder. The powerful chemometric tool, experimental design (ED), will be applied to analyze the variables' interaction and impact on the selected analytical target profiles. Response surface methodology provides a tutorial on using the central composite design with three levels of variables and quadratic programming to optimize the design space of the developed method. Methods: The New HPLC method consisted of an aqueous buffer and ethanol as a green mobile phase run on a reversed-phase symmetry C18 column. A full resolution between the Tigecycline and its degradation product peaks was achieved in a short analytical runtime. Results: Further, the specificity, accuracy, precision, robustness and stability indicating power of the proposed approach were verified through stress degrading testing. Conclusions: Finally, the analytical eco-scale and the green Analytical Procedure Index (GAPI) were utilized to determine how environmentally friendly the recommended method was compared to other published approaches.

Central composite design driven optimization of sustainable stability indicating HPLC method for the determination of Tigecycline and greenness assessment

Background: Tigecycline (TGC) is a recently developed antibiotic to battle resistant bacteria. The procedures outlined in the literature for analyzing TGC involve chemical solvents that could be hazardous. Therefore, this study aimed to create a sustainable and stable HPLC technique for quantifying Tigecycline in lyophilized powder. The powerful chemometric tool, experimental design (ED), will be applied to analyze the variables' interaction and impact on the selected analytical target profiles. Response surface methodology provides a tutorial on using the central composite design with three levels of variables and quadratic programming to optimize the design space of the developed method. Methods: The New HPLC method consisted of an aqueous buffer and ethanol as a green mobile phase run on a reversed-phase symmetry C18 column. A full resolution between the Tigecycline and its degradation product peaks was achieved in a short analytical runtime. Results: Further, the specificity, accuracy, precision, robustness and stability indicating power of the proposed approach were verified through stress degrading testing. Conclusions: Finally, the analytical eco-scale and the green Analytical Procedure Index (GAPI) were utilized to determine how environmentally friendly the recommended method was compared to other published approaches.

Concurrent Determination of Tigecycline, Tetracyclines and Their 4-Epimer Derivatives in Chicken Muscle Isolated from a Reversed-Phase Chromatography System Using Tandem Mass Spectrometry

A quantitative and qualitative method using a high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) detection approach was developed and validated for the analysis of tigecycline, four tetracyclines and their three 4-epimer derivatives in chicken muscle. Samples were extracted repeatedly with 0.1 mol/L Na2EDTA–McIlvaine buffer solution. After vortexing, centrifugation, solid-phase extraction, evaporation and reconstitution, the aliquots were separated using a C8 reversed-phase column (50 mm × 2.1 mm, 5 µm) with a binary solvent system consisting of methanol and 0.01 mol/L trichloroacetic acid aqueous solution. The typical validation parameters were evaluated in accordance with the acceptance criteria detailed in the guidelines of the EU Commission Decision 2002/657/EC and the U.S. Food and Drug Administration Bioanalytical Method Validation 05/24/18. The matrix-matched calibration curve was linear over the concentration range from the limit of quantitation (LOQ) to 400 μg/kg for doxycycline, and the calibration graphs for tetracycline, chlortetracycline, oxytetracycline, their 4-epimer derivatives and tigecycline showed a good linear relationship within the concentration range from the LOQ to 200 μg/kg. The limits of detection (LODs) for the eight targets were in the range of 0.06 to 0.09 μg/kg, and the recoveries from the fortified blank samples were in the range of 89% to 98%. The within-run precision and between-run precision, which were expressed as the relative standard deviations, were less than 5.0% and 6.9%, respectively. The applicability was successfully demonstrated through the determination of residues in 72 commercial chicken samples purchased from different sources. This approach provides a novel option for the detection of residues in animal-derived food safety monitoring.

Rapid detection of plasmid-mediated high-level tigecycline resistance in Escherichia coli and Acinetobacter spp

OBJECTIVES

The emergence and spread of plasmid-encoded tet(X3/X4) genes that confer high-level tigecycline and eravacycline resistance in Escherichia coli and Acinetobacter spp. pose serious threats to human and animal health. We developed a rapid and robust assay to detect Tet(X3/X4) in Gram-negative bacteria based on eravacycline degradation by the presence of the Tet(X) enzyme in the test strain.

METHODS

This tetracycline inactivation method (TIM) is based on the degradation of eravacycline by the Tet(X3/X4)-producing strain, which results in reduced eravacycline activity against an acid-producing thermophile Bacillus stearothermophilus indicator strain. For Tet(X)-negative strains, eravacycline retains its antimicrobial activity. Coupled with a pH-sensitive dye (bromocresol purple), the reduced colorimetric inhibition zone can be measured to determine the production of Tet(X3/X4). One hundred and eighteen isolates, including 30 tet(X4)-positive E. coli, 30 tet(X3)-positive Acinetobacter spp. and 58 tet(X)-negative E. coli and Acinetobacter spp., were examined to evaluate the performance of this TIM.

RESULTS

The sensitivity and specificity for E. coli carrying tet(X4) was 96.7% and 100%, respectively, and for Acinetobacter spp. carrying tet(X3) both were 100%. The TIM assay can be completed within 6.5 h.

CONCLUSIONS

The TIM is a simple, rapid and cost-effective method for the detection of plasmid-mediated high-level tigecycline resistance in E. coli and Acinetobacter spp.

Rapid Detection of High-Level Tigecycline Resistance in Tet(X)-Producing Escherichia coli and Acinetobacter spp. Based on MALDI-TOF MS

The emergence and spread of the novel mobile Tet(X) tetracycline destructases confer high-level tigecycline and eravacycline resistance in Escherichia coli and Acinetobacter spp. and pose serious threats to human and animal health. Therefore, a rapid and robust Tet(X) detection assay was urgently needed to monitor the dissemination of tigecycline resistance. We developed a rapid and simple assay to detect Tet(X) producers in Gram-negative bacteria based on matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). This MALDI^Tet(X) test was based on the inactivation of tigecycline by a Tet(X)-producing strain after a 3-h incubation of bacterial cultures with tigecycline. Culture supernatants were analyzed using MALDI-TOF MS to identify peaks corresponding to tigecycline (586 ± 0.2 m/z) and a tigecycline metabolite (602 ± 0.2 m/z). The results were calculated using the MS ratio [metabolite/(metabolite + tigecycline)]. The sensitivity of the MALDI^Tet(X) test with all 216 test strains was 99.19%, and specificity was 100%. The test can be completed within 3 h. Overall, the MALDI^Tet(X) test is an accurate, rapid, cost-effective method for the detection of Tet(X)-producing E. coli and Acinetobacter spp. by determining the unique peak of an oxygen-modified derivative of tigecycline.

Skin tissue sample collection, sample homogenization, and analyte extraction strategies for liquid chromatographic mass spectrometry quantification of pharmaceutical compounds

Quantification of pharmaceutical compounds in skin tissue is challenging because of low expected concentrations, small typical sample volumes, and the hard nature of the skin structure itself. This review provides a comprehensive overview of sample collection, sample homogenization and analyte extraction methods that have been used to quantify pharmaceutical compounds in skin tissue, obtained from animals and humans, using liquid chromatography-mass spectrometry. For each step in the process of sample collection to sample extraction, methods are compared to discuss challenges and provide practical guidance. Furthermore, liquid chromatographic-mass spectrometry considerations regarding the quality and complexity of skin tissue sample measurements are discussed, with emphasis on analyte recovery and matrix effects. Given that the true recovery of analytes from skin tissue is difficult to assess, the extent of homogenization plays a crucial role in the accuracy of quantification. Chemical or enzymatic solubilization of skin tissue samples would therefore be preferable as homogenization method.

Utility of the fluorogenic characters of benzofurazan for analysis of tigecycline using spectrometric technique; application to pharmacokinetic study, urine and pharmaceutical formulations

Tigecycline (TIGE) is the newest tetracycline derivative antibiotic with low toxicity, it is used for management of infectious diseases caused by Gram-positive and Gram-negative bacteria. Hence, an efficient, selective and sensitive method was developed for analysis of TIGE in commercial formulations, human plasma and urine. The spectrofluorimetric technique based on the reaction of secondary amine moiety in TIGE with 4-chloro-7-nitrobenzofurazan (NBD-Cl) in slightly alkaline medium producing a highly fluorescent product measured at 540 nm (λ_ex at 470 nm) after heating for 15 min at 75°C. The proposed strategy was upgraded and approved by ICH rules and bio-analytical validated using US-FDA recommendations. A linear relationship between fluorescence intensity and TIGE concentration was observed over the concentration range 40-500 ng mL^-1 with limit of quantification (LOQ) 21.09 ng mL^-1 and limit of detection (LOD) 6.96 ng mL^-1 .The ultra-affectability and high selectivity of the proposed strategy permits analysis of TIGE in dosage form, human plasma and urine samples with good recovery ranged from 97.23% to 98.72% and from 99.36% to 99.80% respectively, without any interfering from matrix components. Also, the developed strategy was used to examine the stability of TIGE in human plasma and applied for pharmacokinetic investigation of TIGE.

Determination of tigecycline in human plasma by LC-MS/MS and its application to population pharmacokinetics study in Chinese patients with hospital-acquired pneumonia

A selective, sensitive and rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of tigecycline (TGC) in human plasma, using tigecycline-d₉ as an internal standard (IS). Analytical samples were prepared using a protein precipitation method coupled with a concentration process. The analyte and IS were separated on a reversed-phase Waters Acquity UPLC^® BEH-C₁₈ column (2.1 × 50 mm i.d., 1.7 μm) with a flow rate of 0.25 mL/min. The mobile phase consisted of water, containing 0.2% formic acid (v/v) with 10 mm ammonium formate (A) and acetonitrile (B). The mass spectrometer was operated in selected reaction monitoring mode through electrospray ionization ion mode using the transitions of m/z 586.2 → 513.1 and m/z 595.1 → 514.0 for TGC and IS, respectively. The linearity of the method was in the range of 10-5000 ng/mL. Intra- and inter-batch precision (CV) for TGC was <9.27%, and the accuracy ranged from 90.06 to 107.13%. This method was successfully applied to the analysis of samples from hospital-acquired pneumonia patients treated with TGC, and a validated population pharmacokinetic model was established. This developed method could be useful to predict pharmacokinetics parameters and valuable for further pharmacokinetics/pharmacodynamics studies.

Bioanalysis of drug in tissue: current status and challenges

Distribution of drugs into tissues is an important determinant of the overall PK and PD profile. Thus, bioanalysis of drugs and their metabolites in tissues can play an important role in understanding the pharmacological and toxicological properties of new drug candidates. Unlike liquid matrices, bioanalysis in tissues offers unique challenges such as proper tissue sampling, appropriate tissue sample preparation, efficient extraction of the analytes from the tissue homogenates, and demonstration of stability and recovery of analytes in intact tissues. This article provides a systematic review of tissue sample analysis for small molecules using LC–MS/MS. The authors provide rationale for tissue sample analysis, and discuss strategies for method development, method qualification or validation, and sample analysis. Unique aspects of method development and qualification/validation are highlighted based on authors’ direct experiences and literature summary. Analysis using intact tissue samples such as MALDI imaging is also briefly discussed.

Tissue sample preparation in bioanalytical assays

Analytical quantitation of compounds in tissue has become a more prevalent addition to biological sample analysis in recent times. This increase will most certainly continue to bring the question of proper analytical method validation to the forefront of discussion. Thoughtful design of sample homogenization, analyte fortification and extraction can ensure a successful analysis. This review presents current trends in tissue sample preparation by harvesting, homogenization techniques, as well as concerns for calibrator and QC preparation. Strategies for consideration and resolution of common pitfalls in method development, for example stability issues and control biomatrices in endogenous analysis, are also presented.