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A novel, stability indicating, reverse phase high-performance liquid chromatography (RP-HPLC) method was developed to determine the S-isomer of linagliptin (LGP) in linagliptin and metformin hydrochloride (MET HCl) tablets (LGP–MET HCl) by implementing design of experiment (DoE), i.e., two-level, full factorial design (23 + 3 centre points = 11 experiments) to understand the critical method parameters (CMP) and its relation with the critical method attribute (CMA), and to ensure robustness of the method. The separation of the S-isomer, LGP and MET HCl in the presence of their impurities was achieved on Chiralpak® IA-3 (Amylose tris (3, 5-dimethylphenylcarbamate), immobilized on 3 µm silica gel) stationary phase (250 × 4.6 mm, 3 µm) using isocratic elution and detector wavelength at 225 nm with a flow rate of 0.5 mL·min−1, an injection volume of 10 µL with a sample cooler (5 °C) and column oven temperature of 25 °C. Ethanol:Methanol:Monoethanolamine (EtOH:MeOH:MEA) in the ratio of 60:40:0.2 v/v/v was used as a mobile phase. The developed method was validated in accordance with international council for harmonisation (ICH) guidelines and was applied for the estimation of the S-isomer of LGP in LGP–MET HCl tablets. The same method also can be extended for the estimation of the S-isomer in LGP dosage forms.

The objective of the present work was to develop a sensitive, selective, accurate and precise stability-indicating HPLC method for quantification of degradation products and process-related impurities in fesoterodine fumarate extended-release tablets. The degradation profile was studied by conducting forced degradation studies and all the degradation products formed during degradation were separated. A chromatographic separation was achieved by using Waters Symmetry C18, 250 × 4.6 mm, 5 μm column, maintained at 30°C. Mobile phase A (0.05% trifluoroacetic acid in water) and mobile phase B (90% of 0.02% TFA in methanol and 10% of water) were used in gradient elution mode. A total of 75 μL of each solution was injected and peak responses were quantified at 220 nm. The method was found specific, precise, accurate, linear, rugged, robust and sensitive. During stability studies of fesoterodine fumarate extended-release tablets, one unknown impurity at relative retention time 1.37 was found increasing beyond the identification threshold. This impurity was isolated by using Preparative HPLC and structure was elucidated using mass and NMR spectroscopy. This method is a simple, inexpensive HPLC method that can be used as a routine quality control test for the estimation of impurities in fesoterodine fumarate extended-release tablets. [ABSTRACT FROM AUTHOR]

The objective of the current research is to understand the degradation behavior of avanafil under different stress conditions and to develop a stability-indicating high-performance liquid chromatography (HPLC) method for simultaneous determination of degradants observed during degradation. Avanafil tablets were exposed to acid, base, water, oxidative, thermal, and photolytic degradation conditions. In acid, oxidative, thermal, and humidity degradation, significant degradation was observed. All the degradants observed during degradation were separated from known impurities of avanafil by using reverse-phase (RP)-HPLC. Mobile phase A, 0.1% trifluoro acetic acid and triethylamine in water, and mobile phase B, water and acetonitrile in the ratio of 20:80 (v/v), were used at a flow rate of 1.2 mL/min in gradient elution mode. Separation was achieved by using Inertsil ODS 3 column (3 μm, 4.6 mm × 250 mm) at 45 °C. Peak responses were recorded at 245 nm. Method capability for detecting and quantifying the degradants, which can form during stability, was proved by demonstrating the peak purity of avanafil peak in all the stressed samples. Mass balance was established by performing the assay of stressed sample against reference standard. Mass balance was found >97% for all the stress conditions. The developed analytical method was validated as per International Conference on Harmonization (ICH) guidelines. The method was found specific, linear, accurate, precise, rugged, and robust. [ABSTRACT FROM AUTHOR]

A novel, stability indicating, reverse phase high-performance liquid chromatography (RP-HPLC) method was developed to determine the S-isomer of linagliptin (LGP) in linagliptin and metformin hydrochloride (MET HC1) tablets (LGP-MET HC1) by implementing design of experiment (DoE), i.e., two-level, full factorial design (2³ + 3 centre points = 11 experiments) to understand the critical method parameters (CMP) and its relation with the critical method attribute (CMA), and to ensure robustness of the method. The separation of the S-isomer, LGP and MET HC1 in the presence of their impurities was achieved on Chiralpak® IA-3 (Amylose tris (3, 5-dimethylphenylcarbamate), immobilized on 3 pm silica gel) stationary phase (250 x 4.6 µm, 3 pm) using isocratic elution and detector wavelength at 225 nm with a flow rate of 0.5 mL-min-1, an injection volume of 10 µL with a sample cooler (5 °C) and column oven temperature of 25 °C. Ethanol:Methanol:Monoethanolamine (EtOH:MeOH:MEA) in the ratio of 60:40:0.2 ν/ ν /ν was used as a mobile phase. The developed method was validated in accordance with international council for harmonisation (ICH) guidelines and was applied for the estimation of the S-isomer of LGP in LGP-MET HC1 tablets. The same method also can be extended for the estimation of the S-isomer in LGP dosage forms. [ABSTRACT FROM AUTHOR]