Concomitant pseudopolymorphs of 10-deacetyl baccatin III.

Three new solvates [mono-dimethyl sulfoxide (mono-DMSO), mono-dimethyl acetamide (mono-DMA) and mono-dimethyl formamide (mono-DMF)] of 10-Deacetyl baccatin III, were generated by slow evaporation in DMSO, DMF, and DMSO/DMA (1:1) solvent systems respectively. Two concomitant forms mono-DMSO(a new form) and di-DMSO (a known form) were obtained in the DMSO solvent system. Yet two other concomitant forms mono-DMA (a new form) and di-DMSO (a known form) were obtained in DMSO/DMA (1:1) solvent system. A fourth solvate mono-DMF (a new form) was crystallized in unimolar ratio using DMF as a solvent. These solvates were characterized using powder X-ray diffraction, differential scanning calorimeter, thermogravimetric analysis (TGA), and spectroscopic [(13)C solid-state nuclear magnetic spectroscopy, solution (1)H NMR, and Fourier transform infrared] techniques. The interactions between host and guest molecules were elucitated by single-crystal X-ray diffraction data. In all the cases, guest molecules are connected to the host molecules by O-H∙∙∙O hydrogen bonds. A remarkable difference in the desolvation onset temperatures of di- and mono-DMSO solvates was observed which was also featured by a corresponding weight loss during TGA analysis.

Stability-indicating UPLC method for determination of Imatinib Mesylate and their degradation products in active pharmaceutical ingredient and pharmaceutical dosage forms.

A simple, precise, accurate stability-indicating gradient reverse phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for quantitative determination of purity of Imatinib Mesylate (IMM) drug substance and drug products in the presence of its process related impurities, and degradation products. The proposed RP-UPLC method utilizes Acquity UPLC BEH 50-mm, 2.1mm and 1.7 µm C-18 column at 30 °C, with a gradient program of 9.0 min at a flow rate of 0.3 mL/min. The compounds of interest were monitored at 237 nm. Resolution for Imatinib and eight related components was found to be greater than 1.5 for any pair of components. The correlation coefficients (r(2)>0.9990) obtained indicate clear correlations between the concentrations and their peak areas for the investigated compounds. RSD obtained for the repeatability and intermediate precision experiments, was less than 5.0%. Accuracy of the method was further ascertained by performing recovery studies through spiking experiments. The drug substance was subjected to hydrolytic, oxidative, photolytic and thermal stress conditions as per ICH. The developed method was validated according to the current ICH guidelines for specificity, limit of detection, limit of quantitation, linearity, accuracy, precision, ruggedness and robustness. The method is also suitable for the assay determination of IMM in pharmaceutical dosage forms.

A validated CE method for determining dimethylsulfate a carcinogen and chloroacetyl chloride a potential genotoxin at trace levels in drug substances.

A simple and rapid capillary zone electrophoretic method was developed for determining dimethyl sulfate a possible human carcinogen and mutagen and chloroacetyl chloride a potential genotoxic agent at trace levels in pharmaceutical drug substances by indirect photometric detection. A systematic screening of various anionic probes was performed to obtain the best separation conditions and sensitivity. High sensitivities with low quantification and detection levels were achieved for dimethylsulfate and chloroacetyl chloride using a background electrolyte (BGE) containing 5 mM pyridine dicarboxylic acid as the probe ion. The method is specific, precise and accurate for the two genotoxins. The optimized method was validated for specificity, precision, linearity, accuracy and stability in solution. Calibration curves were linear (R>0.999) for both dimethylsulfate and chloroacetyl chloride in the range LOQ - 300% of nominal concentrations. The CE method was effectively implemented for estimating dimethylsulfate and chloroacetyl chloride in two different active pharmaceutical ingredients (APIs).

Development and validation of a stability indicating HPLC method for simultaneous determination of four novel fluoroquinolone dimers as potential antibacterial agents.

A series of novel 6-fluoro1,4-dihydro-4-oxo-3-quinoline carboxylic acid dimers were synthesized as potential antibacterial agents from commercially available substituted fluorobenzoic acids. A stability indicating HPLC method was developed to determine these novel fluoroquinolone dimers using a systematic method development approach. Samples were subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation; and analyzed to demonstrate the specificity and stability indicating ability of the developed method. The precision for all four fluoroquinolone dimers was within 2.0% RSD. Calibration curves were linear (LOQ, 150%), with regression coefficients >0.99 for all dimers. The method was conveniently applied for determining purity and assay of these four novel fluoroquinolone dimers.

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.

Impurity profile study of loratadine.

Three unknown impurities in loratadine 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). These impurities were isolated from mother liquor sample of loratadine using reversed-phase preparative HPLC. Based on the spectral data (IR, NMR and MS) the structures of these impurities were characterized as 11-(N-carboethoxy-4-piperidylidene)-6,11-dihydro-5H-benzo(5,6) cyclopenta(1,2-b)-pyridine (I), 8-bromo-11-(N-carboethoxy-4-piperidylidene)-6,11-dihydro-5H-benzo(5,6) cyclopenta (1,2-b)-pyridine (II) and 8-chloro-11-(N-carboethoxy-4-piperidylidene)-5H-benzo(5,6) cyclopenta (1,2-b)-pyridine (III). The synthesis of these impurities was discussed.