Enantioselective LC-MS/MS method for the determination of cloperastine enantiomers in rat plasma and its pharmacokinetic application

Principles for Stereoselective Separation of Chiral Drug Compounds Enantiomers and Diastereomers in Pharmaceuticals and Biopharmaceuticals Using Liquid Chromatography

In the fields of pharmaceuticals and biopharmaceuticals, chiral liquid chromatography techniques including high-performance liquid chromatography and ultra-performance liquid chromatography are frequently used to isolate, identify, separate, and quantify chiral isomers, including enantiomers and diastereomers (stereoisomers), due to the significant differences in biological activity and therapeutic effects of stereoisomers. The authors have provided a comprehensive overview of the fundamental principles necessary for using liquid chromatography to separate and accurately estimate chiral compounds that exhibit stereoisomerism (both enantiomers and diastereomers). The development strategies outlined include the selection of chromatographic conditions, optimization of sample preparation, evaluation of degradation pathways, establishment of system suitability criteria, and execution of method validation studies. Additionally, this article supports the development of robust and stability-indicating methods by applying one factor at a time and design of experiments concepts for chiral drugs and their chiral impurities in pharmaceuticals and biopharmaceuticals. The method validation attributes essential to evaluate the characteristics of the developed method were discussed in this write-up. The validation parameters include specificity, linearity, detection limit, quantitation limit, accuracy, precision, solution stability.

Independent concentration extraction as a novel green approach resolving overlapped UV-Vis binary spectra and HPTLC-densitometric methods for concurrent determination of levocloperastine and chlorpheniramine

BACKGROUND

The proposed research study introduces independent concentration extraction (ICE) as a novel UV-Vis spectrophotometric approach. The approach can be used for extracting the concentration of two analytes with severely overlapped spectra from their binary mixtures. ICE is based on spectral extraction platform involving simple smart successive methods that can directly extract the original zero order spectra of the analytes at their characteristic (λmax). Chlorpheniramine maleate (CPM) and Levocloperastine fendizoate (LCF) are two commonly co-formulated drugs in cough preparations. The combined mixture was used to confirm the validity of the developed ICE tool. Another less green HPTLC was developed for the first time to separate both drugs and help also in confirming the proposed tool.

METHODS

For the simultaneous determination of CPM and LCF, two ecologically friendly techniques were employed. The first approach encompasses the use of the ICE spectrophotometric method that could be successively applied for extracting the concentration of two analytes with severely overlapped unresolved spectra in their binary mixtures. Other complementary methods aiming at original spectral extraction; including spectrum subtraction (SS) and unity subtraction (US) were also successfully employed to resolve the zero order spectra of the combined drugs with all their characteristic features and peaks. The second technique used, a high-performance TLC-densitometric one, was performed on silica plates with silica plates F254 and a mobile phase with a ratio of 3:3:3:1 by volume of toluene, ethanol, acetone, and ammonia as a developing system at 230 nm.

RESULTS

The presented extraction approach was executed without any optimization steps or sample pretreatment for the simultaneous determination of CPM and LCF. The method was found to be valid for their determination within concentration range of 3.0-30.0 μg mL-1 for both drugs. For HPTLC method, the resulting Rf values of CPM and LCF were 0.37 and 0.78, within concentration ranges of 0.3-4.0 μg/spot and 0.8-10.0 μg/spot, respectively. Greenness assessment of both developed methodologies showed that the HPTLC method is less green than the spectrophotometric method, yet with comparable sustainability when it comes to the used technique.

CONCLUSION

The procedures were found to be selective, accurate, and precise for analysis of the studied binary mixture. Furthermore, the environmental impact of the introduced methods was assessed using novel greenness metrics, namely AGREE and Green Analytical Procedure Index (GAPI) to prove their ecological safety. In addition, white analytical chemistry (WAC) evaluation metric was employed to ensure the synergy and coherence of analytical, practical, and ecological attributes.

Sustainable and Green Fluorescence Method for the Determination of Cloperastine in Human Plasma: Greenness Assessment

A newly green method for the sensitive quantification of cloperastine, a cough suppressant, in spiked human plasma and its pharmaceutical formulation was designed for the first time. The established method depends on the enhancement of the weak fluorescence of cloperastine using 50 mM sulfuric acid to impair the photoinduced electron transfer produced from the nitrogen atom of piperidine moiety in cloperastine. This full protonation in an acid medium leads to an enhancement in the fluorescence of cloperastine, permitting its linear determination from 0.2 to 5.0 µg/mL with LOD and LOQ of 0.04 and 0.13 µg/mL, respectively. Moreover, the studied drug was estimated in its pharmaceutical market formulations as well as spiked human plasma. Furthermore, the greenness of the described method was evaluated.

Enantioselective LC-MS/MS determination of antidepressants, β-blockers and metabolites in agricultural soil, compost and digested sewage sludge

In this work, an analytical method was optimised and validated for the simultaneous extraction and enantioselective determination of chiral β-blockers, antidepressants and two of their metabolites in agricultural soils, compost and digested sludge. Sample treatment was based on ultrasound-assisted extraction and extract clean-up by dispersive solid-phase extraction. Analytical determination was carried out by liquid chromatography-tandem mass spectrometry using a chiral column. Enantiomeric resolutions were in the range from 0.71 to 1.36. Accuracy was in the range from 85 to 127% and precision, expressed as relative standard deviation, was lower than 17% for all the compounds. Method quantification limits were below 1.21-52.9 ng g^-1 dry weight (dw) in soil, 0.76-35.8 ng g^-1 dw in compost and 13.6-90.3 ng g^-1 dw in digested sludge. Application to real samples revealed enantiomeric enrichment in the range especially in compost and digested sludge (enantiomeric fractions up to 1).

Simultaneous separation of atenolol enantiomers and its acid/alkaline degradation impurities on mixed-mode chiral ligand exchange stationary phases

Simultaneous separation of the enantiomer and impurities is a huge challenge for the quality control of the chiral drug. In this work, mixed-mode chiral ligand exchange stationary phases (CSPs) modified by octyl and sulfhydryl ligands were prepared by vapor deposition and click chemistry methods. Qualitative and quantitative determination of the prepared CSPs were achieved by Fourier transform infrared spectroscopy, solid-state ¹³ C CP/MAS NMR, and elemental analysis. The chiral resolution of CSPs was investigated through a comprehensively chromatographic evaluation of various racemates. Besides, the thermodynamic experiment was carried out to elucidate the contribution of hydrophobic ligand to the improvement of chiral recognition and selectivity. Atenolol and its degradation products were analyzed on the synthesized CSPs and compared with the commercial chiral column. A good separation of atenolol enantiomers from its acid and alkaline degradation impurities was simultaneously achieved on the C₈ /L-Hypro CSP. This new CSP is expected to have more applications in the quality control of other chiral drugs.

An overview of chiral separations of pharmaceutically active substances by HPLC (2018-2020)

This review provides a brief survey of chiral separation of pharmaceutically active substances published over the last 3 years (2018-2020). Chiral separation of drugs is an important area of research. The control of enantiomeric purity and determination of individual enantiomeric drug molecules is a necessity especially for clinical, analytical, and regulatory purposes. Among chromatographic resolution methods, high-performance liquid chromatography based on chiral stationary phases remains the most popular and effective method used for chiral separation of various drugs. In this review, attention is paid to several classes of chiral stationary phases that have been the most frequently used for drug enantioseparation during this period.

GRAPHIC ABSTRACT