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Pilli N.R.,Jawaharlal Nehru University | Pilli N.R.,Wellquest Clinical Research | Inamadugu J.K.,Jawaharlal Nehru University | Mullangi R.,Jubilant Biosys | And 3 more authors.
Biomedical Chromatography | Year: 2011

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 C18 column by pumping 0.1% formic acid-acetonitrile (15:85, v/v) at a flow rate of 1mL/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 0.26-210ng/mL for ATO; 0.05-20.5ng/mL for AML; 0.25-208ng/mL for RAM and 0.74-607ng/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 2.5min 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. © 2010 John Wiley & Sons, Ltd. Source


Polagani S.R.,Rayalaseema University | Polagani S.R.,Wellquest Clinical Research | Pilli N.R.,Wellquest Clinical Research | Gajula R.,Wellquest Clinical Research | Gandu V.,Osmania University
Journal of Pharmaceutical Analysis | Year: 2013

A simple, rapid and sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay method has been developed and fully validated for the simultaneous quantification of atorvastatin, metformin and glimepiride in human plasma. Carbamazepine was used as internal standard (IS). The analytes were extracted from 200 μL aliquots of human plasma via protein precipitation using acetonitrile. The reconstituted samples were chromatographed on a Alltima HP C18 column by using a 60:40 (v/v) mixture of acetonitrile and 10 mM ammonium acetate (pH 3.0) as the mobile phase at a flow rate of 1.1 mL/min. The calibration curves obtained were linear (r2≥0.99) over the concentration range of 0.50-150.03 ng/mL for atorvastatin, 12.14-1207.50 ng/mL for metformin and 4.98-494.29 ng/mL for glimepiride. The API-4000 LC-MS/MS in multiple reaction monitoring (MRM) mode was used for detection. The results of the intra- and inter-day precision and accuracy studies were well within the acceptable limits. All the analytes were found to be stable in a battery of stability studies. The method is precise and sensitive enough for its intended purpose. A run time of 2.5 min for each sample made it possible to analyze more than 300 plasma samples per day. The developed assay method was successfully applied to a pharmacokinetic study in human male volunteers. © 2012 Xi'an Jiaotong University. Source


Polagani S.R.,Rayalaseema University | Polagani S.R.,Wellquest Clinical Research | Pilli N.R.,Wellquest Clinical Research | Maddela R.,Wellquest Clinical Research | And 2 more authors.
Journal of Pharmaceutical and Biomedical Analysis | Year: 2013

This paper describes a simple, rapid and sensitive liquid chromatography/tandem mass spectrometry assay for the determination of cycloserine in human plasma using carbamazepine as internal standard (IS). Analyte and the IS were extracted from the 50μL of human plasma via protein precipitation using acetonitrile. The chromatographic separation was achieved on a C18 column by using a mixture of acetonitrile-0.5% formic acid buffer (60:40, v/v) as the mobile phase at a flow rate of 0.8mL/min. The calibration curve obtained was linear (r2≥0.99) over the concentration range of 50-15,000ng/mL. Method validation was performed as per FDA guidelines and the results met the acceptance criteria. A run time of 2.5min for each sample made it possible to analyze more number of samples in short time, thus increasing the productivity. The proposed method was found to be applicable to pharmacokinetic studies. © 2012 Elsevier B.V. Source

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