Development of stability-indicating UHPLC method for the quantitative determination of silodosin and its related substances.

A novel, specific and stability-indicating reversed-phase (RP) ultra-high-performance liquid chromatography (UHPLC) method, which is mass compatible, was developed and validated for the quantitative determination of silodosin and its related substances. Silodosin was subjected to stress conditions like hydrolysis (acid and basic), oxidation, photolysis and thermal degradation, as per the guidelines of the International Conference Harmonization, to show that the method is stability-indicating. The proposed UHPLC method has a resolution of greater than 2.0 between silodosin and its process-related impurities. The chromatographic separation was achieved on an Agilent Poroshell 120 EC-C18 column (50 × 4.6mm i.d.; particle size, 2.7 µm). The method employed a linear gradient elution using a mobile phase consisting of acetonitrile and 10 mM ammonium acetate buffer with 0.1% triethyl amine, with pH adjusted to 6.0, monitored at 273 nm. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness. The known process impurities were separated and their structure was confirmed by using liquid chromatography-mass spectrometry and direct mass analysis.

Complexity in estimation of esomeprazole and its related impurities' stability in various stress conditions in low-dose aspirin and esomeprazole magnesium capsules.

A complex, sensitive, and precise high-performance liquid chromatographic method for the profiling of impurities of esomeprazole in low-dose aspirin and esomeprazole capsules has been developed, validated, and used for the determination of impurities in pharmaceutical products. Esomeprazole and its related impurities' development in the presence of aspirin was traditionally difficult due to aspirin's sensitivity to basic conditions and esomeprazole's sensitivity to acidic conditions. When aspirin is under basic, humid, and extreme temperature conditions, it produces salicylic acid and acetic acid moieties. These two byproducts create an acidic environment for the esomeprazole. Due to the volatility and migration phenomenon of the produced acetic acid and salicylic acid from aspirin in the capsule dosage form, esomeprazole's purity, stability, and quantification are affected. The objective of the present research work was to develop a gradient reversed-phase liquid chromatographic method to separate all the degradation products and process-related impurities from the main peak. The impurities were well-separated on a RP8 column (150 mm × 4.6mm, X-terra, RP8, 3.5µm) by the gradient program using a glycine buffer (0.08 M, pH adjusted to 9.0 with 50% NaOH), acetonitrile, and methanol at a flow rate of 1.0 mL min(-1) with detection wavelength at 305 nm and column temperature at 30°C. The developed method was found to be specific, precise, linear, accurate, rugged, and robust. LOQ values for all of the known impurities were below reporting thresholds. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis, and thermal degradation in the presence of aspirin. The developed RP-HPLC method was validated according to the present ICH guidelines for specificity, linearity, accuracy, precision, limit of detection, limit of quantification, ruggedness, and robustness.

Development and validation of an UPLC method for rapid determination of ibuprofen and diphenhydramine citrate in the presence of impurities in combined dosage form.

A novel, stability-indicating gradient reverse-phase ultra-performance liquid chromatographic method was developed for the simultaneous determination of ibuprofen and diphenhydramine citrate in the presence of degradation products and process related impurities in combined dosage form. The method was developed using C18 column with mobile phase containing a gradient mixture of solvent A and B. The eluted compounds were monitored at 220 nm. Ibuprofen and diphenhydramine citrate were subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal, and photolytic degradation. Major unknown impurity formed under oxidative degradation was identified using LC-MS-MS study. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantitation, accuracy, precision and robustness. The described method was linear over the range of 0.20-6.00 µg/mL (r>0.998) for Ibuprofen and 0.084-1.14 µg/mL for diphenhydramine citrate (r>0.998). The limit of detection results were ranged from 0.200-0.320 µg/mL for ibuprofen impurities and 0.084-0.099 µg/mL for diphenhydramine citrate impurities. The limit of quantitation results were ranged from 0.440 to 0.880 µg/mL for ibuprofen impurities and 0.258 to 0.372 µg/mL for diphenhydramine citrate impurities. The recovery of ibuprofen impurities were ranged from 98.1% to 100.5% and the recovery of diphenhydramine citrate impurities were ranged from 97.5% to 102.1%. This method is also suitable for the simultaneous assay determination of ibuprofen and diphenhydramine citrate in pharmaceutical dosage forms.

A validated stability-indicating normal phase LC method for clopidogrel bisulfate and its impurities in bulk drug and pharmaceutical dosage form.

A novel stability-indicating normal phase liquid chromatographic (NP-LC) method was developed for the determination of purity of clopidogrel drug substance and drug products in bulk samples and pharmaceutical dosage forms in the presence of its impurities and degradation products. This method is capable of separating all the related substances of clopidogrel along with the chiral impurities. This method can be also be used for the estimation of assay of clopidogrel in drug substance as well as in drug product. The method was developed using Chiralcel OJ-H (250mmx4.6mm, 5microm) column. n-Hexane, ethanol and diethyl amine in 95:5:0.05 (v/v/v) ratio was used as a mobile phase. The eluted compounds were monitored at 240nm. Clopidogrel bisulfate was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. The degradation products were well resolved from main peak and its impurities, proving the stability-indicating power of the method. The developed method was validated as per International Conference on Harmonization (ICH) guidelines with respect to specificity, limit of detection, limit of quantification, precision, linearity, accuracy, robustness and system suitability.

Analysis of duloxetine hydrochloride and its related compounds in pharmaceutical dosage forms and in vitro dissolution studies by stability indicating UPLC.

A reproducible gradient reversed-phase ultra-performance liquid chromatographic method is developed for quantitative determination of duloxetine hydrochloride in pharmaceutical dosage forms. The method is also applicable for analysis of related substances and for study of in vitro dissolution profiles. Chromatographic separation is achieved on a 50 mm × 4.6 mm, 1.8 µm C-18 column. Mobile phase A contains a mixture of 0.01 M KH(2)PO(4) (pH 4.0) buffer, tetrahydro furan, and methanol in the ratio 67:23:10 (v/v/v), respectively, and mobile phase B contains a mixture of 0.01 M KH(2)PO(4), (pH 4.0) buffer, and acetonitrile in the ratio 60:40 (v/v), respectively. The flow rate is 0.6 mL/min, and the detection wavelength is monitored at 236 nm. Resolution of duloxetine hydrochloride and three potential impurities is greater than 2.0 for all pairs of components. The drug was subjected to ICH prescribed hydrolytic, oxidative, photolytic, and thermal stress conditions. Method is validated for linearity, specificity, accuracy, precision, ruggedness, and robustness.

A validated stability-indicating UPLC method for desloratadine and its impurities in pharmaceutical dosage forms.

A novel stability-indicating gradient reverse phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for the determination of purity of desloratadine in presence of its impurities and forced degradation products. The method was developed using Waters Aquity BEH C18 column with mobile phase containing a gradient mixture of solvents A and B. The eluted compounds were monitored at 280nm. The run time was 8min within which desloratadine and its five impurities were well separated. Desloratadine was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Desloratadine was found to degrade significantly in oxidative and thermal stress conditions and stable in acid, base, hydrolytic and photolytic degradation conditions. The degradation products were well resolved from main peak and its impurities, thus proved the stability-indicating power of the method. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also suitable for the assay determination of desloratadine in pharmaceutical dosage forms.