Reversed phase liquid chromatography method with fluorescence detection of gemifloxacin in rat plasma and its application to the pharmacokinetic study

Fabrication and Applications of Potentiometric Membrane Sensors Based on Specific Recognition Sites for the Measurement of the Quinolone Antibacterial Drug Gemifloxacin

Supramolecular gemifloxacin (GF) sensors have been developed. Supramolecular chemistry is primarily concerned with noncovalent intermolecular and intramolecular interactions, which are far weaker than covalent connections, but they can be exploited to develop sensors with remarkable affinity for a target analyte. In order to determine the dose form of the quinolone antibacterial drug gemifloxacin, the current study's goal is to adapt three polyvinylchloride (PVC) membrane sensors into an electrochemical technique. Three new potentiometric membrane sensors with cylindric form and responsive to gemifloxacin (GF) were developed. The sensors' setup is based on the usage of o-nitrophenyl octyl ether (o-NPOE) as a plasticizer in a PVC matrix, β-cyclodextrin (β-CD) (sensor 1), γ-cyclodextrin (γ-CD) (sensor 2), and 4-tert-butylcalix[8]arene (calixarene) (sensor 3) as an ionophore, potassium tetrakis (4-chlorophenyl) borate (KTpClPB) as an ion additive for determination of GF. The developed method was verified according to IUPAC guidelines. The sensors under examination have good selectivity for GF, according to their selectivity coefficients. The constructed sensors demonstrated a significant response towards to GF over a concentration range of 2.4 × 10^-6, 2.7 × 10^-6, and 2.42 × 10^-6 mol L^-1 for sensors 1, 2, and 3, respectively. The sensors showed near-Nernstian cationic response for GF at 55 mV, 56 mV, and 60 mV per decade for sensors 1, 2, and 3, respectively. Good recovery and relative standard deviations during the day and between days are displayed by the sensors. They demonstrated good stability, quick response times, long lives, rapid recovery, and precision while also exhibiting good selectivity for GF in various matrices. To determine GF in bulk and dose form, the developed sensors have been successfully deployed. The sensors were also employed as end-point indicators for titrating GF with sodium tetraphenyl borate.

Microdialysis combined with liquid chromatography-tandem mass spectrometry for the quantitation of gemifloxacin and its application to a muscle penetration study in healthy and MRSA-infected rats

Pharmacological efficacy is based on the drug concentration in target tissues, which usually cannot be represented by the plasma concentration. The purpose of this study was to compare the pharmacokinetic characteristics of gemifloxacin in plasma and skeletal muscle and evaluate its tissue penetration in both healthy and MRSA (methicillin-resistant Staphylococcus aureus)-infected rats. A microdialysis (MD) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated to determine free gemifloxacin concentrations in rat plasma and skeletal muscle simultaneously. The in vivo recoveries of MD were 23.21% ± 3.42% for skeletal muscle and 20.62% ± 3.19% for plasma, and were concentration independent. We provided evidence that the method developed here meets FDA requirements. Additionally, this method was successfully applied to the determination of free gemifloxacin in rats. Muscle and blood dialysates were collected after an 18 mg/kg intravenous bolus dose. The mean areas under the concentration-time curves (AUCs) from 0 to 9 h for skeletal muscle and plasma were 3641.50 ± 915.65 h*ng/mL and 7068.32 ± 1964.19 h*ng/mL in MRSA-infected rats and 3774.72 ± 700.36 h*ng/mL and 6927.49 ± 1714.86 h*ng/mL in healthy rats, respectively. There was no significant difference (P>0.05) in gemifloxacin exposure between healthy rats and MRSA-infected rats for plasma or muscle. The low ratio of AUC0-9 muscle to AUC0-9 plasma suggested lower drug exposure in skeletal muscle than in plasma for both healthy and MRSA-infected rats. Our study suggested that the administration of gemifloxacin according to drug levels in plasma to treat local infection is unreasonable and might result in an inadequate dose regimen.

Determination of Quinolone Antibiotic Residues in Human Serum and Urine Using High-Performance Liquid Chromatography/Tandem Mass Spectrometry

Quinolone antibiotic residues may pose potential threat to human health. A rapid and sensitive method was developed for the determination of quinolone residues in human serum and urine. After solid phase extraction (SPE) process, eight quinolone residues were analyzed by high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) using ciprofloxacin-d8 as the internal standard. The relative standard deviation of intra-day and inter-day precision for the eight quinolones were less than 7.52% and the accuracies ranged from 95.8% to 103% in human serum, and from 94.1% to 104% in human urine. The extraction recoveries for the eight quinolones varied from 80.2% to 113% in human serum and 83.4% to 117% in human urine. The limit of detection for the eight quinolones was 0.50–1.00 ng/mL. Quinolone antibiotic residues in human serum and urine from 12 volunteers were successfully analyzed with the validated method. The SPE-HPLC-MS/MS method was useful for accurate determination of quinolone antibiotic residues in human body.

Quantitative analysis of drugs in biological matrices by HPLC hyphenated to fluorescence detection

An overview of the state-of-the art in HPLC coupled with fluorescence detection is presented. Over the last 20 years, the increasing number of methodological papers on this topic (4082 between 1994 and 2004 and 7725 between 2004 and 2014) is testament to its utility in bioanalytical applications. Compared with conventional UV absorbance detection used in HPLC, fluorescence detection can greatly enhance the sensitivity leading to limits of detection similar to those obtained with mass spectrometry, offering researchers a sensitive, robust and relatively inexpensive instrumental method. This work will focus on the analysis of pharmaceutical compounds in different biological matrices, either naturally fluorescent or derivatized with a fluorescent agent, and some of them chiral. Therapeutic applications, sample preparation and derivatization, sensitivity for each example are described.