A validated UPLC-MS/MS method for the analysis of linezolid and a novel oxazolidinone derivative (PH027) in plasma and its application to tissue distribution study in rabbits

A Novel UPLC-MS/MS Assay for the Measurement of Linezolid and its Metabolite PNU-142300 in Human Serum and its Application to Patients With Renal Insufficiency

The contribution of the metabolites of linezolid to the associated myelosuppression is unknown in patients who are renal impairment. In this research, the purpose of our experiment was to explore and develop a quick and robust ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) assay for the determination of linezolid and its metabolite PNU-142300 in human serum simultaneously. The analytes were prepared using a simple and convenient approach with acetonitrile for protein crash, and then separated from the matrix on a Waters Acquity Ultra performance liquid chromatography (UPLC) BEH C18 (2.1 mm × 50 mm, 1.7 μm) column in a program of gradient elution, where the mobile phase was consisted of water with 0.1% formic acid and acetonitrile, and was placed at 0.40 ml/min flow rate. Multiple reaction monitoring (MRM) was employed and conducted for UPLC-MS/MS detection with ion transitions at m/z 338.01 → 296.03 for linezolid, m/z 369.96 → 327.98 for PNU-142300 and m/z 370.98 → 342.99 for tedizolid (Internal standard, IS), respectively. This method had good linearity respectively in the calibration range of 0.01–20 μg/ml for linezolid, and 0.05–100 μg/ml for PNU-142300. In the intra- and inter-day, the precision of linezolid and PNU-142300 was below 14.2%, and the accuracy in this method was determined to be from −9.7 to 12.8%. In addition, recovery and matrix effect of the analytes were all found to be acceptable, and the analytes during the assay and storage in serum samples were observed to be stable. The novel optimized UPLC-MS/MS assay was also successfully employed to determine the concentration levels of linezolid and PNU-142300 in human serum. The results showed that linezolid-associated myelosuppression occurs more frequently in patients with renal insufficiency, and the metabolite-to-parent concentration ratio of PNU-142300 is predicted to reduce this toxicity of myelosuppression.

UPLC-Q-TOF-MS Study of the Mechanism of THSWD for Breast Cancer Treatment

Taohong Siwu decoction (THSWD) is a classic traditional Chinese medicine (TCM) prescription that is widely used in the clinical treatment of gynecological and cerebrovascular diseases. Here we used a method that coupled ultra-performance liquid chromatography to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) in which both positive and negative ion modes were established to investigate the major constituents in THSWD. A Waters ACQUITY UPLC BEH C18 column (2.1 mm×100 mm, 1.7 μm) was used to separate the aqueous extract of THSWD. The mobile phase consisted of 0.1% aqueous formic acid (A) and acetonitrile (B). Ninety-five components were identified in two different ion modes, including aromatic acids, flavones, polysaccharides, volatile oils monoterpene glycosides, aromatic cyanogenic glycosides, and others. Pathological changes in tumors and serum expression of interleukin-4 in a mouse model of breast cancer were detected after THSWD treatment. The results showed that THSWD had obvious therapeutic effects. This study establishes a material basis for the use of THSWD in the treatment of breast cancer.

Defect-engineering a metal–organic framework for CO2 fixation in the synthesis of bioactive oxazolidinones

Three-component, solvent-free cycloaddition of epoxides with aromatic amines and CO₂.

A critical review of HPLC-based analytical methods for quantification of Linezolid

Linezolid is a synthetic antimicrobial agent belonging to the oxazolidinone class. Since its approval in the year 2000 until now, linezolid remains the main representative drug for the oxazolidinone class of drugs, which is used in therapy due to its unique mode of action, which involves inhibition of protein synthesis. As linezolid holds great importance in antimicrobial therapy, it is necessary to compile the various analytical methods that have been reported in the literature for its analysis. Analytical techniques used for pharmaceutical analyses and therapeutic drug monitoring play an important role in comprehending the aspects regarding bioavailability, bioequivalence, and therapeutic monitoring during patient follow-ups. Even though linezolid has had the approval for clinical use for more than 18 years now, most of the analytical methods for its determination reported in the scientific literature are the ones which utilize HPLC. Therefore, the present review provides a summary of the HPLC-based methods used in the determination and quantification of linezolid in different matrices since the time of its discovery.

Linezolid-A Review of Analytical Methods in Pharmaceuticals and Biological Matrices

Bacterial resistance to antibiotics is a growing phenomenon in the world. Considering the relevance of antimicrobials for population and the reduction in the registration of new antimicrobials by regulatory agencies, proper quality control is required to minimize the spread of bacterial resistance and ensure the effectiveness of a treatment, as well as safety for the patient. The recent addition to the antimicrobial world is the oxazolidinone classes of antibiotics, especially useful to treat infections caused by Gram-positive bacteria. Eperezolid and linezolid (LIN) are the two members of the oxazolidinone class of antibiotics. LIN was the first oxazolidinone approved by the Food and Drug Administration. The present review focuses on the analytical methods for the assessment of LIN in pharmaceuticals and biological matrices. The critical validation parameters like the linearity, limit of detection, limit of quantification are discussed for the individual method. Also the critical quality attributes like the sensitivity and the sample preparation techniques for bioanalytical methods are also discussed. Furthermore, some future trends that can be incorporated in the determination of similar drugs are also suggested.

A metal–metalloporphyrin framework based on an octatopic porphyrin ligand for chemical fixation of CO2with aziridines

A new porous metal–metalloporphyrin framework, MMPF-10, was synthesized for CO₂cycloaddition with aziridines.

Antimycobacterial Activities of N-Substituted-Glycinyl 1H-1,2,3-Triazolyl Oxazolidinones and Analytical Method Development and Validation for a Representative Compound

Twelve N-substituted-glycinyl triazolyl oxazolidinone derivatives were screened for antimycobacterial activity against susceptible (Mycobacteriumtuberculosis (Mtb) H37Rv) and resistant (isoniazid (INH)-resistant Mtb (SRI 1369), rifampin (RMP)-resistant Mtb (SRI 1367), and ofloxacin (OFX)-resistant Mtb (SRI 4000)) Mtb strains. Most of the compounds showed moderate to strong antimycobacterial activity against all strains tested, with minimum inhibitory concentration (MIC) value ranges of 0.5-11.5, 0.056-11.6, 0.11-5.8, and 0.03-11.6 μM, and percent inhibition ranges of 41-79%, 51-72%, 50-75%, and 52-71% against Mtb H37Rv, INH-R, RMP-R, and OFX-R M.tuberculosis, respectively. The 3,5-dinitrobenzoyl and 5-nitrofuroyl derivatives demonstrated strong antimycobacterial activities with the N-(5-nitrofuroyl) derivatives (PH-145 and PH-189) being the most potent, with MIC value range of 0.3-0.6 μM against all strains tested. Compounds were not bactericidal, but showed intracellular (macrophage) antimycobacterial activity. A reliable validated analytical method was developed for a representative compound PH-189 using Waters Acquity ultra High-Performance Liquid Chromatography (UHPLC) system with quaternary Solvent Manager (H-Class). A simple extraction method indicated that PH-189 was stable in human plasma after 90 min at 37 °C with more than 90% successfully recovered. Moreover, stress stability studies were performed and degradants were identified by using UHPLC-ESI-QToF under acidic, basic, and oxidative simulated conditions.

Comparative Pharmacokinetic Study for Linezolid and Two Novel Antibacterial Oxazolidinone Derivatives in Rabbits: Can Differences in the Pharmacokinetic Properties Explain the Discrepancies between Their In Vivo and In Vitro Antibacterial Activities?

This is a comparative pharmacokinetics study of linezolid (Lzd), and two novel oxazolidinone antibacterial agents—PH027 and PH051—in rabbits to determine if the discrepancy between the in vitro and in vivo activities of the novel compounds is due to pharmacokinetic factors. The pharmacokinetics after IV and oral administration, plasma protein binding and tissue distribution for the three compounds were compared. The elimination half-lives were 52.4 ± 6.3, 68.7 ± 12.1 and 175 ± 46.1 min for Lzd, PH027 and PH051, respectively. The oral bioavailability for Lzd, PH027 and PH051 administered as suspension were 38.7%, 22.1% and 4.73%, which increased significantly when administered as microemulsion to 51.7%, 72.9% and 13.9%. The plasma protein binding were 32–34%, 37–38% and 90–91% for Lzd, PH027 and PH051. The tissue distribution for PH027 and PH051 in all investigated tissues were higher than that for Lzd. It can be concluded that the lower bioavailability of PH027 and PH051 compared to Lzd when administered as suspension is the main cause of their lower in vivo activity, despite their comparable in vitro activity. Differences in the other pharmacokinetic characteristics cannot explain the lower in vivo activity. The in vivo activity of the novel compounds should be re-evaluated using formulations with good oral bioavailability.