Rapid and Simultaneous Analysis of Multiple Classes of Antimicrobial Drugs by Liquid Chromatography-Tandem Mass Spectrometry and Its Application to Routine Biomedical, Food, and Soil Analyses.

Antimicrobial agents (AMAs) are widely exploited nowadays to meet the high demand for animal-derived food. It has a significant impact on the food chain whose end consumers are human beings. The burden of AMAs on humans comes from either meat or crops cultivated on soil containing high residual antibiotics, which are responsible for the global crisis of antibiotic resistance. Thus, the objective of this study was to design a selective and sensitive liquid chromatography-mass spectrometry (LC-MS)/MS-based simultaneous bioanalytical method for estimation of twenty AMAs in human plasma, raw meat, and soil samples. The selective extraction of all analytes from the above matrices was performed by the solid-phase extraction clean-up method to overcome the interferences. Analytes were separated on a Waters Symmetry Shield C18 (150 × 4.6 mm2, 5 µm) column, using an isocratic solvent system of methanol-0.5% formic acid (80:20, v/v) with 0.75 mL/min flow rate. The average extraction recoveries for all analytes in plasma were ranged from 42.0 to 94.0% with relative standard deviations (RSDs) below ±15%. All of the validation parameters are in accordance with the United State Food and Drug Administration (USFDA) guidelines. Moreover, the method was also valid for a broad plasma concentration range and can be proposed as an excellent method for routine pharmacokinetic studies, therapeutic drug monitoring, clinical analysis, and detection and quantitation of AMA remnants in raw meat as a standard quality control test for human consumption.

Assessment of in vitro metabolic stability, plasma protein binding, and pharmacokinetics of E- and Z-guggulsterone in rat.

Guggulsterone is a racemic mixture of two stereoisomers (E- and Z-), obtained from the gum resin of Commiphora mukul and it is marketed as an antihyperlipidemic drug. The aim of our study was to assess the in vitro and in vivo absorption, distribution, metabolism, and excretion (ADME) properties namely solubility, in vitro metabolism, plasma protein binding and oral pharmacokinetic studies of E- and Z-guggulsterone. In vitro metabolism experiments were performed by using rat liver and intestinal microsomes. In vitro intrinsic clearance (CLint ) was found to be 33.34 ± 0.51 and 39.23 ± 8.12 µL/min/mg protein in rat liver microsomes for E- and Z-isomers, respectively. Plasma protein binding was determined by equilibrium dialysis method and in vivo pharmacokinetic studies were performed in male Sprague Dawley (SD) rats. Both isomers were highly bound to rat plasma proteins (>95% bound). Plasma concentration of E- and Z-isomers decreased rapidly following oral administration and were eliminated from systemic circulation with a terminal half-life of 0.63 ± 0.25 and 0.74 ± 0.35 h, respectively. The clearance (CL) for E-isomer was 2.79 ± 0.73 compared to 3.01 ± 0.61 L/h/kg for Z-isomer, indicating no significant difference (student t test; p <0.05) in their elimination.The pharmacokinetics of both isomers was characterized by extensive hepatic metabolism as seen with rat liver microsomes with high clearance and low systemic availability in rats. In brief, first-pass metabolism seems to be responsible factor for low bioavailability of guggulsterone. Copyright © 2015 John Wiley & Sons, Ltd.

Assessement of the pharmacokinetics, tissue distribution and excretion studies of a novel antiplatelet agent S007-867, following administration to rats.

S007-867 is a promising novel antiplatelet agent with better efficacy and lesser bleeding risk than existing agents. The present study investigated the absorption, tissue distribution, and excretion of S007-867 in rat model for further advancement of the molecule. A simple and robust ultra fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) bioanalytical method was used to determine S007-867 in various matrices. Following oral administration, the compound was quickly dispersed in the various tissues and peak concentration levels were achieved within 0.5-1 h. Overall, exposure of drug, i.e., AUC in different tissues was found in the order of small intestine > liver > heart > spleen > lungs > kidney > brain. The total recoveries of the S007-867 within 96 h were 3.36% in urine and faeces. This might be due to a first-pass effect by the liver and intestine as most of the drug was eliminated in metabolite form. These findings provide a crucial information about further development of S007-867 as antithrombotic agent. Copyright © 2015 John Wiley & Sons, Ltd.

Simultaneous quantitation of acetylsalicylic acid and clopidogrel along with their metabolites in human plasma using liquid chromatography tandem mass spectrometry.

The interest in therapeutic drug monitoring has increased over the last few years. Inter- and intra-patient variability in pharmacokinetics, plasma concentration related toxicity and success of therapy have stressed the need of frequent therapeutic drug monitoring of the drugs. A sensitive, selective and rapid liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous quantification of acetylsalicylic acid (aspirin), salicylic acid, clopidogrel and carboxylic acid metabolite of clopidogrel in human plasma. The chromatographic separations were achieved on Waters Symmetry Shield(TM) C18 column (150 × 4.6 mm, 5 µm) using 3.5 mm ammonium acetate (pH 3.5)-acetonitrile (10:90, v/v) as mobile phase at a flow rate of 0.75 mL/min. The present method was successfully applied for therapeutic drug monitoring of aspirin and clopidogrel in 67 patients with coronary artery disease.

Pharmacokinetics and tissue distribution study of novel potent antiplatelet agent S007-867 in mice using HPLC-MS/MS.

1. S007-867 is a novel antiplatelet agent that shows promising in vitro and in vivo efficacy. For further development and better pharmacological elucidation, we characterized pharmacokinetics and tissue distribution of S007-867 in a mouse model. 2. A sensitive, selective and robust LC-MS/MS method was developed and validated in the mouse plasma and tissue for quantification of S007-867. The chromatographic separation was performed on Waters Symmetry Shield C18 column (150 × 4.6 mm, 5 µm) using methanol and ammonium acetate buffer. 3. S007-867 was rapidly absorbed and distributed to various tissues. Following single oral administration of S007-867 in the mouse, the concentration was in the order of C intestine > C liver > C kidney > C heart > C spleen > C lungs > C brain. Tissue to plasma area under the plasma curve ratio suggested that the maximum amount of drug was found in the intestine and liver. Half life of S007-867 was found longer in the heart (8.08 h), spleen (∼ 7.94 h) and kidney (∼ 15.41 h) as compared with other tissues. 4. The preclinical pharmacokinetics and tissue distribution data obtained using this LC-MS/MS method are expected to assist the future clinical investigations of S007-867 as a promising antiplatelet agent.

Amphotericin-B entrapped lecithin/chitosan nanoparticles for prolonged ocular application.

Fungal keratitis is the major cause of vision loss worldwide. Amphotericin-B is considered as the drug of choice for fungal infections. However, its use in ophthalmic drug delivery is limited by the low precorneal residence at ocular surface as a result of blinking reflex, tear turnover and nasopharyngeal drainage. We report Amphotericin-B loaded lecithin/chitosan nanoparticles for prolonged ocular application. The prepared nanoparticles were in the size range of 161.9-230.5 nm, entrapment efficiency of 70-75%, theoretical drug loading of 5.71% with positive zeta potential of 26.6-38.3 mV. As demonstrated by antifungal susceptibility against Candida albicans and Aspergillus fumigatus, nanoparticles were more effective than marketed formulation. They exhibited pronounced mucoadhesive properties. In-vivo pharmacokinetic studies in New Zealand albino rabbit eyes indicated improved bioavailablity (∼ 2.04 fold) and precorneal residence time (∼ 3.36 fold) by nanoparticles prepared from low molecular weight chitosan as compared with marketed formulation.

Corneal targeted nanoparticles for sustained natamycin delivery and their PK/PD indices: an approach to reduce dose and dosing frequency.

Natamycin is the only approved medication for the treatment of mycotic keratitis. Current dosage regimen include one drop of natamycin suspension (5% w/v) instilled in the conjunctival sac at hourly or two hourly intervals for several days which has poor patient compliance. The purpose of the present study was to design a corneal targeted nanoformulation in order to reduce dose and dosing frequency of natamycin and evaluate its pharmacokinetic/pharmacodynamic indices in comparison with clinical marketed preparation. The nanoparticles prepared by nanoprecipitation method were in nanometer size range with high entrapment efficiency and positive surface charge. In-vitro release studies indicated prolonged release of natamycin up to 8h. In-vitro antifungal activity was comparable with marketed preparation. The performance of nanoformulations was evaluated in rabbit eyes. The concentration of natamycin in tear fluid was determined by using LC-MS/MS. The pharmacokinetic parameters such as area under the curve, t½ and mean residence time were significantly higher and clearance was significantly lower for nanoformulations with that of marketed preparation. The optimized dosing schedule to maintain natamycin concentration above tenfold of MIC90 was one instillation in every 5h. Moreover, 1/5th dose reduction of nanoformulation was also effective.