A new rapid and sensitive high performance liquid chromatography (HPLC) method has been developed for the simultaneous determination of atorvastatin-an antihyperlipidemic drug along with most commonly prescribed drugs (antihyperlipidemic,antihypertensive,antidiabetic,antithrombotic) in bulk and marketed combined formulations.The chromatographic separation was carried out by gradient elution mode with acetonitrile as organic modifier and 0.1％ triethylamine acetate (TEAA) buffer pH 5 at a flow rate of 1 mL/min and a diode array detector at wavelength 230 nm was employed for detection of the analytcs.Calibration curves were linear in the range of 5 -150 μg/mL for all the drugs with correlation coefficients of determination (r2 values) ≥ 0.999.Limits of detection (LODs) and Limits of quantification (LOQs) ranged from 0.1 to 0.27 μg/mL and 0.3 to 0.89 μg/mL respectively.Intra-day and inter-day precision was studied at three concentration levels (20,60 and 100 μg/mL).The intra-day and inter-day RSD for all compounds was less than 2.0％.The accuracy for all compounds was found to be between 98％ and 102％.Thus,the performance of the method described allows its use in quantification of atorvastatin along with 9 most commonly prescribed drugs available in market as atorvastatin combined dosage forms.

A simple, precise, accurate stability-indicating gradient reversed-phase high-performance liquid chromatographic (RP-HPLC) method was developed for the quantitative determination of zotepine (ZTP) in bulk and pharmaceutical dosage forms in the presence of its degradation products (DPs). The method was developed using Phenomenex C18 column (250 mm ~ 4.6 mm i.d., 5 mm) with a mobile phase containing a gradient mixture of solvents, A (0.05%trifluoroacetic acid (TFA), pH ? 3.0) and B (acetonitrile). The eluted compounds were monitored at 254 nm;the run time was within 20.0 min, in which ZTP and its DPs were well separated, with a resolution of 41.5. The stress testing of ZTP was carried out under acidic, alkaline, neutral hydrolysis, oxidative, photolytic and thermal stress conditions. ZTP was found to degrade significantly in acidic, photolytic, thermal and oxidative stress conditions and remain stable in basic and neutral conditions. The developed method was validated with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness as per ICH guidelines. This method was also suitable for the assay determination of ZTP in pharmaceutical dosage forms. The DPs were characterized by LC-MS/MS and their fragmentation pathways were proposed.