Simultaneous determination of simvastatin, lovastatin and niacin in human plasma by LC-MS/MS and its application to a human pharmacokinetic study.

A simple, sensitive and specific LC-MS/MS method for simultaneous determination of simvastatin (SV), lovastatin (LV) and niacin (NIA) in human plasma was developed and validated on API-4000 in positive ion mode. Nevirapine was used as internal standard (IS). The assay procedure involved a simple one-step liquid-liquid extraction of SV, LV, NIA and the IS from plasma into ethyl acetate. Separation of SV, LV, NIA and the IS was achieved on an Alltima C18 column with a mobile phase consisting of 5 mm ammonium acetate (pH 4.5) and acetonitrile (20:80, v/v) pumped at a flow rate of 1 mL/min. Nominal retention times obtained for SV, LV, NIA and IS were 2.12, 1.67, 0.50 and 0.65 min, respectively. The lower limits of quantification (LLOQ) for SV, LV and NIA were 0.10, 0.10 and 25.2 ng/mL, respectively. The response function was established for the range of concentrations 0.10-101 ng/mL for SV and LV, and 25.2-5020 ng/mL for NIA, with a coefficient of correlation of >0.99 for all the compounds. Method validation was performed as per FDA guidelines and the results met the acceptance criteria. The proposed method was found to be applicable to clinical studies.

A rapid and sensitive LC-MS/MS method for quantification of donepezil and its active metabolite, 6-o-desmethyl donepezil in human plasma and its pharmacokinetic application.

A rapid and sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay method has been developed and fully validated for simultaneous quantification of donepezil and its active metabolite, 6-o-desmethyl donepezil in human plasma. Analytes and the internal standard were extracted from human plasma by liquid-liquid extraction technique using a 30:70 v/v mixture of ethyl acetate and n-hexane. The reconstituted samples were chromatographed on a C(18) column by using a 70:30 v/v mixture of acetonitrile and ammonium formate (5 mm, pH 5.0) as the mobile phase at a flow rate of 0.6 mL/min. The calibration curve obtained was linear (r ≥ 0.99) over the concentration range of 0.09-24.2 ng/mL for donepezil and 0.03-8.13 ng/mL for 6-o-desmethyl donepezil. The results of the intra-day and inter-day precision and accuracy studies were well within the acceptable limits. The proposed method was successfully applied for the estimation of the drug in real time plasma samples for pharmacokinetic studies.

Simultaneous determination of atorvastatin, amlodipine, ramipril and benazepril in human plasma by LC-MS/MS and its application to a human pharmacokinetic study.

A rapid, simple, sensitive and specific LC-MS/MS method has been developed and validated for the simultaneous estimation of atorvastatin (ATO), amlodipine (AML), ramipril (RAM) and benazepril (BEN) using nevirapine as an internal standard (IS). The API-4000 LC-MS/MS was operated under the multiple-reaction monitoring mode using electrospray ionization. Analytes and IS were extracted from plasma by simple liquid-liquid extraction technique using ethyl acetate. The reconstituted samples were chromatographed on C(18) column by pumping 0.1% formic acid-acetonitrile (15:85, v/v) at a flow rate of 1 mL/min. A detailed validation of the method was performed as per the FDA guidelines and the standard curves were found to be linear in the range of 0.26-210 ng/mL for ATO; 0.05-20.5 ng/mL for AML; 0.25-208 ng/mL for RAM and 0.74-607 ng/mL for BEN with mean correlation coefficient of ≥0.99 for each analyte. The intra-day and inter-day precision and accuracy results were well with in the acceptable limits. A run time of 2.5 min for each sample made it possible to analyze more than 400 human plasma samples per day. The developed assay method was successfully applied to a pharmacokinetic study in human male volunteers.

New Validated Stability-Indicating Rp-HPLC Method for Simultaneous Estimation of Atorvastatin and Ezetimibe in Human Plasma by Using PDA Detector.

PURPOSE: This paper describes a simple, precise and accurate RP-HPLC method for simultaneous estimation of atorvastatin and ezetimibe in plasma. METHODS: The chromatographic separation of the drugs were performed on an X-Terra C8 (4.6 x 150 mm, 3.5 mm), with phosphate buffer [pH 3.5 with Ortho Phosphoric Acid] - acetonitrile 40:60 (v/v) as mobile phase. The detection was performed at 235 nm. The flow rate was maintained at 1.2 mL/min. The run time was 8.0 min. RESULTS: The accuracy and reliability of the method was assessed by evaluation of linearity (5-25 µg/mL for both atorvastatin calcium and ezetimibe), precision (intra-day RSD 0.57 % and inter-day RSD 0.02 % for atorvastatin calcium and intra-day RSD 0.56 % and inter-day RSD 0.1 % for ezetimibe), accuracy (100.08- 100.84 % for atorvastatin calcium and 100.56- 101.00 % for ezetimibe), and specificity, in accordance with ICH guidelines. The LLOQ obtained by the proposed method were 1.294 and 1.384 µg/mL for atorvastatin and ezetimibe respectively. CONCLUSION: Overall the proposed method was found to be suitable and accurate for the quantitative determination in plasma. The method was effectively separated the drug from plasma.

Simultaneous determination of losartan, losartan acid and amlodipine in human plasma by LC-MS/MS and its application to a human pharmacokinetic study.

INTRODUCTION: A simple, rapid and sensitive liquid chromatography-tandem mass spectrometric assay method has been developed and fully validated for simultaneous quantification of losartan and its active metabolite, losartan carboxylic acid, and amlodipine in human plasma. Irbesartan was used as an internal standard. MATERIALS AND METHODS: The analytes were extracted from human plasma samples by solid-phase extraction technique using Oasis HLB cartridges, (Waters Corporation, Mumbai, India). The reconstituted samples were chromatographed on a C18 column by using an 85:15, v/v mixture of methanol and 0.1% v/v formic acid as the mobile phase at a flow rate of 1.0 mL/min. A detailed validation of the method was performed as per the FDA guidelines. RESULTS: The calibration curves obtained were linear (r ≥ 0.99) over the concentration range of 0.5-1000 ng/mL for losartan and for its active metabolite losartan acid and 0.05-10.1 ng/mL for amlodipine. The results of the intra- and inter-day precision and accuracy studies were well within the acceptable limits. CONCLUSIONS: A run time of 2.5 min for each sample made it possible to analyze more than 300 plasma samples per day. The proposed method was found to be applicable to clinical studies.

Superior wound healing effect of topically delivered silver nanoparticle formulation using eco-friendly potato plant pathogenic fungus: synthesis and characterization.

Biosynthesis of silver Nanoparticles (NPs) using microorganisms has been reported but methodologies of synthesis are slow and the silver nanoparticles are not stable. In this study, an attempt has been made to synthesize the silver nanoparticles (SNPs) within 10 min from Phytophthora infestans and it was found to be stable. The SNPs formation was confirmed by changes in colour and also from the UV spectral analysis. The sizes of the particles were confirmed by Transmission Electron Microscopy (TEM), particle size measurement. The Fourier transform infrared spectroscopy confirmed the presence of protein as the stabilizing agent surrounding the SNPs. The physical stability was also tested, and the stability of the nanoparticles was confirmed by zeta potential measurement and by SDS-PAGE profiling. Once the SNP ointment was prepared; the wound healing activity of the SNPs was studied by measuring wound contraction ability in excision wound model at different time intervals and histopathology, the least effective dose of SNP 0.125% (w/w) ointments showed significant wound healing as compared to standard silver sulphadiazine ointment currently available in the market.

Development and validation of a HPLC method for the determination of voriconazole in pharmaceutical formulation using an experimental design.

A rapid and sensitive RP-HPLC method with UV detection (260nm) for routine analysis of voriconazole in a pharmaceutical formulation (Vfend((R))) was developed. Chromatography was performed with mobile phase containing a mixture of acetonitrile and water (50:50, v/v) with flow rate was of 1.0mlmin(-1). Quantitation was accomplished with internal standard method. The procedure was validated for linearity (correlation coefficient=0.9999), accuracy, robustness and intermediate precision. Experimental design was used for validation of robustness and intermediate precision. To test robustness, three factors were considered. Percentage of acetonitrile in mobile phase, flow rate and p(H); an increase in the flow rate results in a decrease of the drug found concentration, while the percentage of organic modifier and p(H) have no important effect on the response. For intermediate precision measure the variables considered were: analyst, equipment and number of days. The R.S.D. value (0.45%, n=24) indicated a good precision of the analytical method. The proposed method was simple, highly sensitive, precise and accurate and retention time less than 4min indicating that the method is useful for routine quality control.