Ultrafast liquid chromatographic analysis of erdosteine in human plasma based on fluorimetric detection and precolumn derivatization with 4-bromomethyl-7-methoxycoumarin: Application to pharmacokinetic studies

Multiple green spectroscopic methods for erdosteine determination in bulk and dosage form with extensive greenness evaluation

Four simple, sensitive, economical, and eco-friendly spectrophotometric and spectrofluorimetric methods for the assay of erdosteine (ERD) in bulk and dosage form have been developed and validated as per the current ICH guidelines. Method I involved the addition of the powerful oxidizing agent, potassium permanganate to ERD and measuring the oxidation product at 600 nm. Another oxidizing agent; ceric ammonium sulfate was used in Method II where ERD is oxidized resulting in a decline in the absorbance intensity of cerium (IV) ions, measured at 320 nm. Similarly, Method III employed the use of ceric ammonium sulfate, However, the fluorescence intensity of the resulting cerium (III) ions was recorded at λex/λem 255/355 nm, respectively. Whereas in Method IV, ERD was added to acriflavine leading to a proportional decrease in its native fluorescence. Various reaction conditions affecting the intensity of measurement were attentively investigated, optimized, and validated. All the suggested methods did not require any tedious extraction procedures nor organic solvents. The implementation of the proposed methods in ERD assay resulted in linear relationships between the measured signals and the corresponding concentrations of ERD in the range of 1-6, 0.1-1.0, 0.01-0.1, and 10-100 μg/mL with LOD values 0.179, 0.024, 0.0027 and, 3.2 μg/mL for methods I, II, III and IV respectively. The suggested methods were successfully applied to ERD analysis in pure form and in commercial capsules. Furthermore, the eco-friendliness of the proposed methods was thoroughly checked using various greenness testing tools. Lastly, this work, not only presents highly sensitive, green, mix-and-read methods for ERD determination, but also, describes the determination of ERD spectrofluorimetrically for the first time in the literature.

A rapid and sensitive UPLC–MS/MS method for quantification of erdosteine as bulk drug and in capsules as dosage forms

A rapid, sensitive, specific ultra-performance liquid chromatography-tandem mass spectrometric (UPLC-MS-MS) method was developed for the determination of erdosteine (ERD) in pharmaceutical preparations. The chromatographic separation was achieved with 0.1% formic acid in combination with acetonitrile (25:75 v/v) using C18 UPLC column, 95Å, 2.1 x 50 mm, 1.8 µm. The flow rate was 0.15 mL/min and the total run time was 2.0 min. The column temperature was kept constant at 40 °C and the injection volume was 5 μL. Ibuprofen was used as internal standard (IS). The mass transitions of ERD and IS were m/z 249.9 → 231.8 and 205.1 → 161.0. Also, another product ion of ERD (m/z 249.80 → 231.80) was monitored as predictive ion during the analysis. The standard calibration curve shows determination coefficient (R2) greater than 0.996 with a range of 1-5000 ng/mL using the linear regression model. Within-run precision and between-run repeatability were expressed as relative standard deviation and were lower than 5%. The developed method was successfully applied in the analysis of ERD-containing capsule formulation indicating that the method could be used for routine quality control analyses. Keywords: erdosteine, UPLC-MS/MS, multiple reaction monitoring, pharmaceutical analysis, method validation

Determination, Isolation, and Identification, of Related Impurities in Erdosteine Bulk Drug

BACKGROUND

Erdosteine is a mucolytic drug and has antioxidant activity.

OBJECTIVE

To develop a HPLC method for determination of erdosteine and its impurities in erdosteine bulk drug and identify the main impurities to help improve the quality of erdosteine bulk drug.

METHOD

The chromatographic separations were performed on a CAPCELL PAK C18 column (4.6 mm × 250 mm i.d., 5 μm). Acetonitrile-0.01 mol/L citric acid solution (13:87, v/v) pumped at a flow rate of 1.0 mL/min was used as the mobile phase. Detection wavelength was 254 nm. Two main impurities in erdosteine bulk drug were enriched by ODS column chromatography and oxidative degradation, respectively, and then both were purified by semi-preparative HPLC. At last, their structures were identified by a variety of spectral data (MS, 1H NMR and 13C NMR).

RESULTS

Good separations for erdosteine and its related impurities were observed. A new impurity was confirmed as ethyl ({2-oxo-2-[(2-oxotetrahydro-3-thiophenyl) amino] ethyl} sulfanyl) acetate, which was erdosteine ethyl ester, and produced in the refining process of erdosteine bulk drug when using ethanol as refining solvent. Another impurity was confirmed as ({2-Oxo-2-[(2-oxotetrahydro-3-thiophenyl) amino] ethyl} sulfinyl) acetic acid, which was an erdosteine oxide.

CONCLUSIONS

A HPLC method for determination of erdosteine and its related impurities is developed and validated. Two main impurities in erdosteine bulk drug were isolated and identified. Avoiding ethanol as refining solvent can improve the purity of erdosteine bulk drug.

HIGHLIGHTS

A new process related impurity and an oxidative degradation impurity in erdosteine bulk drug were isolated and identified.

Derivatization procedures and their analytical performances for HPLC determination in bioanalysis

Derivatization, or chemical structure modification, is often used in bioanalysis performed by liquid chromatography technique in order to enhance detectability or to improve the chromatographic performance for the target analytes. The derivatization process is discussed according to the analytical procedure used to achieve the reaction between the reagent and the target compounds (containing hydroxyl, thiol, amino, carbonyl and carboxyl as the main functional groups involved in derivatization). Important procedures for derivatization used in bioanalysis are in situ or based on extraction processes (liquid-liquid, solid-phase and related techniques) applied to the biomatrix. In the review, chiral, isotope-labeling, hydrophobicity-tailored and post-column derivatizations are also included, based on representative publications in the literature during the last two decades. Examples of derivatization reagents and brief reaction conditions are included, together with some bioanalytical applications and performances (chromatographic conditions, detection limit, stability and sample biomatrix).