ABSTRACT A simple and isocratic HPLC method with stability indicating nature was developed and then subsequently validated for simultaneous determination of ciprofloxacin and dexamethasone in pharmaceutical formulations, human serum and urine. Best chromatographic separations were attained within run time of 10 minutes using C8 as stationary phase and mixture of phosphate buffer and methanol (41:59 v/v) as mobile phase. The mobile phase was flowed at 1.5 mL min−1 with detection of both the analytes at 270 nm using photodiode array detector. Validation of the method was accomplished using specificity, linearity, accuracy, precision, robustness, LOD and LOQ. The method was found linear from 3-21 mg mL−1 for ciprofloxacin (r2 ≥ 0.999) and 1-7 mg mL−1 for dexamethasone (r2 ≥ 0.999). The %age recoveries of ciprofloxacin in spiked human urine and serum were ≥99% and ≥85% respectively, while for dexamethasone they were ≥97% in both matrices. The method proficiently separated the peaks of ciprofloxacin and dexamethasone from all types of interfering substances including degradation products/impurities with purity index ≥ 0.9998. The method thus was stability-indicating and can be employed for simultaneous analysis of ciprofloxacin and dexamethasone in complex matrices involving multiple components in the mixture.

Abstract In this study, conditions were optimized for development of a simple RP-HPLC method for simultaneous analysis of gatifloxacin and dexamethasone in different matrices like pharmaceuticals, human serum and urine. Good separation of gatifloxacin and dexamethasone from the induced degradation products was accomplished using C8 as stationary phase; 0.02 M phosphate buffer (pH 3.0) and methanol (42:58 v/v) as mobile phase. The concentration was measured with DAD at 270 nm. Linearity was observed in the range of 0.000040-0.000280 mol/L for gatifloxacin (r2≥0.999) and 0.000013-0.000091 mol/L for dexamethasone (r2≥0.999). Both the analyte peaks were completely separated from the peaks of induced degradation products as indicated by the peak purity index (≥0.9999 for both analytes). The optimized method is recommended to be used for concurrent analysis of gatifloxacin and dexamethasone in different matrices.

Synthesis of sultams was performed using ligand free palladium catalyst following Heck cyclization. The diverse synthesized intermediates in this strategy includes halogenated sulfonyl chloride, alkyl/aryl sulfonamides, N-alkylation using halogenated alkenyl reagents followed by improved Heck cyclization with Pd(OAc)2/DIPA in 1-methyl-pyrolidin-2-one/toluene. In this way, isomeric six membered sultams with endocyclic & exocyclic double bonds (benzothiazine) and seven membered (thiazipene) were obtained. Endocyclic double bond isomer was dominates in respect of yield over the exocyclic double bond isomer. The isolated amounts of endocyclic sultams and thiazipene were almost equal in amounts. The intermediates and final products were characterized using IR, ¹H-NMR, 13C-NMR and EI-MS techniques.

A stability-indicating RP-HPLC method is presented for determination of gatifloxacin and flurbiprofen in binary combination. Gatifloxacin, flurbiprofen and their degradation products were detected at 254 nm using a BDS Hypersil C8 (250 X 4.6 mm, 5 µm) column and mixture of 20 mM phosphate buffer (pH 3.0) and methanol 30:70 v/v as mobile phase. Response was linear over the range of 15-105 mg mL-1 for gatifloxacin (r² > 0.998) and of 1.5-10.5 mg mL-1 for flurbiprofen (r² > 0.999). The developed method efficiently separated the analytical peaks from degradation products (peak purity index > 0.9999). The method developed can be applied successfully for determination of gatifloxacin and flurbiprofen in human serum, urine, pharmaceutical formulations, and their stability studies.

A simple, precise, sensitive and validated reverse-phase high performance liquid chromatographic (RP-HPLC) method was developed for the simultaneous estimation of rosuvastatin and ezetimibe in human plasma. The method involved protein precipitation and extraction of both drugs from plasma using acetonitrile and then separation on a C-18 column. Both the analytes were detected at a wavelength of 240 nm using diode array detector. Mobile phase for the said separation consists of a mixture of 1.5% phosphoric acid and acetonitrile in 30:70, v/v ratio. Linearity was in the range of 0.32-267 mg/mL for rosuvastatin and 0.08-67 mg/mL for ezetimibe with coefficient of determination between 0.9997 and 0.9967. Limit of detection was 0.106 μg/mL for rosuvastatin and 0.026 mg/mL for ezetimibe whereas limit of quantification was 0.32 mg/mL and 0.08 mg/mL for rosuvastatin and ezetimibe respectively. Recovery of both the analytes was greater than 75% with RSD less than 15 %. The total run time was less than five min for the two components. The developed method can be fruitfully employed for the determination of these two drugs in human plasma.

O presente estudo descreve o desenvolvimento e a subsequente validação de indicador de estabilidade simples e acurada por RP-HPLC para a determinação de esparfloxacino e dexametasona em formulações farmacêuticas na presença de produtos de degradação induzidos por estresse. Tanto os fármacos quanto os produtos de degradação induzidos pelo estresse foram separados em 10 minutos, utilizando coluna C8 e mistura de methanol e tampão fosfato 0,02 M, pH 3,0 (60:40 v/v, respectivamente) como fase móvel e detector de arranjo de diodo a 270 nm, A análise de regressão mostrou linearidade na faixa de 15-105 µg/mL para esparfloxacino e 5-35 µg/mL para a dexametsona. Todos os analitos foram resolvidos adequadamente com tailing aceitável. O pico de pureza dos dois foi maior que 0.9999, não mostrando picos de co-eluição. O método desenvolvido foi aplicado para a determinação simultânea de esparfloxacino e dexametasona em formulações farmacêuticas e para estudos de estabilidade.

The present study describes the development and subsequent validation of simple and accurate stability indicating RP-HPLC method for the determination of sparfloxacin and dexamethasone in pharmaceutical formulations in the presence of their stress-induced degradation products. Both the drugs and their stress-induced degradation products were separated within 10 minutes using C8 column and mixture of methanol and 0.02 M phosphate buffer pH 3.0 (60:40 v/v, respectively) as mobile phase at 270 nm using diode array detector. Regression analysis showed linearity in the range of 15-105 µg/mL for sparfloxacin and 5-35 µg/mL for dexamethasone. All the analytes were adequately resolved with acceptable tailing. Peak purity of the two drugs was also greater than 0.9999, showing no co-elution peaks. The developed method was applied for simultaneous determination of sparfloxacin and dexamethasone in pharmaceutical formulations for stability studies.

A simple, RP-HPLC method was established for determining moxifloxacin and ketorolac in pharmaceutical formulations. Moxifloxacin, ketorolac and their degradation products were separated using C8 column with methanol and phosphate buffer pH 3.0 (55:45 v/v) as the mobile phase. Detection was performed at 243 nm using a diode array detector. The method was validated using ICH guidelines and was linear in the range 20-140 µg mL-1 for both analytes. Good separation of both the analytes and their degradation products was achieved using this method. The developed method can be applied successfully for the determination of moxifloxacin and ketorolac.

The present study reports the development and validation of a simple, economic and sensitive HPLC method for the concurrent determination of naproxen and esomeprazole in pharmaceutical formulations. Isocratic chromatography was performed with C-18 column and mixture of phosphate buffer (pH 6.1) and acetonitrile in ratio of (40:60, v/v) at 1.5 mlmin-1. The eluents were monitored at 302 nm using UV detector. The method was isocratic in the range of 9.38 to 300 µgml-1 for naproxen and 0.5 to 16 µgml-1 for esomeprazole. Validation of the method was performed by testing parameters like linearity, accuracy, precision, robustness, specificity, LOD and LOQ values. In the specificity the drugs were subjected to forced degradation studies like acidic, basic, oxidative and thermal stresses. Both the analytes were separated within three minutes. As the method separates the degradation products produced during forced degradation studies from the active analytes so it can be used not only for regular determination of naproxen and esomeprazole but also for their stability studies.

A simple, sensitive and isocratic reverse phase high performance liquid chromatographic (RP-HPLC) method has been developed for the simultaneous determination of olmesartan medoxomil and amlodipine in pharmaceutical tablet formulations. HPLC analysis was carried out using reverse phase isocratic elution with aC18 column and amobilephase of 0.05 Mammonium acetate pH 6.8 and acetonitrile intheratio of 40:60, v/v. Detection of the analytes was achieved using UV detector at 239 nm. The retention times of olmesartan medoxomil and amlodipine were 2.50 and 3.94 respectively Linearity of the method was found to be in the concentration range of 16-112 µgml-1 for olmesartan medoximil and 4-28 µgml-1 for amlodipine. The correlation coefficient value was greaterthan 0.9999 for both the analytes. The method is suitable for the estimation of both the components simultaneously in pharmaceutical tablet formulations.