Sajja Eswaraiah

Impurity profile study of repaglinide.

Three unknown impurities and a byproduct in repaglinide bulk drug at levels below 0.1% (ranging from 0.05 to 0.1%) were detected by a simple isocratic reversed-phase high performance liquid chromatography (HPLC) method. These impurities were isolated from crude sample of repaglinide using reversed-phase preparative high performance liquid chromatography. Based on the spectroscopic data (IR, NMR and MS) the structures of these impurities (I, II and IV) and byproduct (III) were characterised as 4-carboxymethyl-2-ethoxy-benzoic acid (I), 4-cyclohexylaminocarbamoylmethyl-2-ethoxy-benzoic acid (II), 1-cyclohexyl-3-[3-methyl-1-(2-piperidin-1-yl-phenyl)-butyl]-urea (IV) and 1,3-dicyclohexyl urea (III), respectively. Their synthesis and formation is discussed.

Development of Novel RP-HPLC Method for Separation and Estimation of Critical Geometric Isomer and Other Related Impurities of Tafluprost Drug Substance and Identification of Major Degradation Compounds by Using LC–MS

A novel, simple, sensitive and stability-indicating reverse-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for the quantitative determination of the geometric isomer (Trans) and other related substances in the active pharmaceutical ingredient (API) of Tafluprost (TFL), with their determination by an assay. A chromatographic separation of TFL and its impurities was achieved with a C18 analytical column, using gradient elution with mobile phase A consisting of a mixture of water, methanol and orthophosphoric acid (900:100:1, v/v) and mobile phase B consisting of a mixture of acetonitrile and water (900:100, v/v). The instrumental settings included a flow rate of 1.0 mL/min for related substances and 1.2 mL/min for the assay, a column temperature of 50°C and a detector wavelength of 210 nm, using a photodiode array detector. TFL was exposed to thermal, photolytic, hydrolytic and oxidative stress conditions and the stressed samples were analyzed by the proposed method. Peak homogeneity data of TFL were obtained by using a photodiode array detector in the stressed sample chromatograms, which demonstrated the specificity of the method for estimation in the presence of degradants. The developed method was validated for parameters such as precision, accuracy, linearity, limit of detection, limit of quantification, ruggedness and robustness as per ICH guidelines.

A Rapid Novel HPLC Method for Estimation of Eight Related Compounds in Azilsartan Kamedoxomil and Identification of Degradation Compounds by Using LC-MS

A novel, rapid, specific and stability-indicating reverse-phase high-performance liquid chromatography method was developed for the quantitative determination of related compounds, obtained from two different synthetic routes and degradation products of Azilsartan kamedoxomil (AZL). The method was developed by using a YMC-Pack pro C18 (150 × 4.6 mm, 3 µm) column with a mobile phase containing a gradient mobile phase combination. The eluted compounds were measured at wavelength 220 nm. The developed method run time was 25 min, within which AZL and its eight impurities were well separated with minimum 3.0 resolution. The drug substance was subjected to stress conditions of hydrolysis (acid, base and water), oxidation, photolysis, sunlight, 75% relative humidity and thermal degradation as per International Conference on Harmonization (ICH) prescribed stress conditions to ascertain the stability-indicating power of the method. Significant degradation was observed during acid, base, peroxide, water hydrolysis and 75% relative humidity studies. The mass balance of AZL was close to 100% in all the stress condition. The developed method was validated as per the ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness.