Abstract:
A simple, rapid, sensitive liquid chromatography-tandem mass spectrometry method was developed and validated for simultaneous analysis of endogenous estradiol and estrone in human plasma. The analytes were extracted by liquid-liquid extraction with dicholormethane, whcih was then evaporated and derivatized with dansyl chloride, and injected into the LC/MS/MS system. THe chromatographic separation was performed and on revere phase sunfire C18 column with a mobile phase comprising formic acid and acetonitrile in gradient mode. The mass transitions of m/z 506.12/170.66 for 3-dansyl-estradiol, m/z 504.10/170.66 for 3-dansyl estrone were monitored usng multiple reaction-monitoring (MRM) modes for quantification. With the optimumtuning parameters, the lower level of quantification for estradiol in human plasma was 15.64 pg mL^-1 and 16.0 mL^-1 for estrone and estradiol, respectively. Acceptable precision and accuracy were obtained for concentrations over the standard curve range of 15-1250 pg Ml^-1. This procedure could potentially be used in the investigation of estrogen for pathophysilogical assessment and other clinical appliations, including pharmacokinetic studies.

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Determination and Validation of an LC Method of Bendroflumethiazide in Human Plasma and its Pharmacokinetics

Authors : D. Bhavesh, P. Srinivasa, P Parag, P Brijesh, R. Shivprakash, V. Prasanthkumar

Abstract:
A simple, rapid, sensitive high performence liquid chromatography with flourescent detaction was developed and validated for the determination of bendoflumethiazide in human plasma. Extraction from the plasma was by liquid-liquid extration using ethyl acetate. Mosapride citrate was used as the internal standard. The chromatographic separation was perfomed on reverse phase LiChroshere C18 column with mobile phase comprising of acetonitrile and phosphate buffer (38:62 v/v). The assay precision ranged ranged from 0.9 - 12.5 and accuracy between 96.8 - 108.8 %, revealing that the method has good reproducibility over the concentration range of 0.98 - 100.16 ng m/L. The validated method had been applied to analyse the bendroflumethiazide concentrations for application in pharmacokinetc, bioavailibility or bioequivalence studies.

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LC determination and pharmacokinetics of Meloxicam

Authors : Bhavesh Dasandi, Shivprakash, Saroj H., K M Bhatt J.Pharm. Biomed Ana, [28(2002)999-1004]

Abstract:
A simple and rapid HPCL assay method for the estimation of meloxicam in plasma was developed .The method totally eliminated the solvent extraction procedure. The plasma proteins were precipitated using perchloric acid(70%) and acetonitrile mixture (1:1v/v)and the supernatant was directly injected to the HPCL system.The Separation was achieved on a Lichrospher C18 5µ(125*4.0mm)analytical column with a mobile phase of sodium acetate buffer (pH 3.3 ,170 mmol)acetonitrile (62.38v/v)mixture.Detection was by UV detector at 355 nm.The retention time observed for meloxicam and piroxicam (internal standard)were at 6.0 and 4.0 min ,repectively . The response was linear over a range of 50 - 1500 ng ml -1 in human plasma .The method was simple, specific, precise and accurate . The method was also used for the bioequivalence study of meloxicam formulation in healthy human Indian, male valunteers.
© 2002 Elsevier Science B.V. All rights reserved.

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Determination of Doxazocin in human plasma by reversed phase ion-pair HPLC with fluorescence Detection

Authors : D. Bhavesh, S.Pinal, V.Saroj, Shivprakash
Indian Journal of Pharmaceutical science [2002,64,(4):354-356]

Abstract:
A high performance liquid chromatographic method was develpoed for the estimation of doxazosin in human plasma . It employs a simple and rapid method of sample preparation . Doxazosin and intenal standard (prazosin)were chromatographed as ion pairs with heptane sulphonic acid. Sample preparation involved liquid-liquid extraction with diethylether, evaporation of the organic layer reconstitution of the residue into mobile phase and injection of 20 µl into the chromatograph.Chromatograph was performed using ODS C18 5µ reverse phase column with fluorescence detection.Mobile phase consisted of heptane sulphonic acid buffer and methanol. At a flow rate of 1.2 ml/min,one analysis was completed in less than10min . The method was sensitive and reproducibel with accurate detecation as low as 0.1 ng/ml in plasma . The method was linear for doxazosin concentrations in the range of 0.5 -30 ng/ml (r2 =0.9976). Recoveries for the same drug concentrations from spiked human plasma ranged from 90-95% (n=5). The mean RSD values for interdaya and intraday assay reproducibility (n=5) were 4.47 % and 4.52 % respecively. Peak area ratios were fit to a least squares liner regression algorithm with a 2/x weighting . LOD and LOQ of the method were found to be 0.1 ng/ml and 0.5 ng/ml respectively.

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Development of HPLC assay method for the estimation of Olanzapine in human plasma and its application to pharmacokinetics

Authors : Dasandi Bhavesh, Shah Pinal, Gandhi Chetan, Bhatt K.M., Shivprakash
Accepted for publication in Indian Drugs, Won Best research paper award from Indian Drugs Manufacturers Associations.

Abstract:
A new method for the estimation of olanizapine in human plasma is developed and validated . It utilizes RP select B column and amperometric detector . The mobile phase consisted of 75mM sodium dihydrogen phospate buffer of pH 7.0 acetonitrile and method in 55:22.5:22.5% v/v ratios in an isocratic mode at 1.5 ml-1 flow rate .The drug is extracted in to 3ml each of Tertiary Butyl Methyl Ether (TBME)twice form plasma evaporated and the residue dissolved in mobile phase . The percentage extraction is found to be more than 79% and the linearity range from 0.5ng to 50.0ng ml-1. The method has been validated extensively and found to have good interday and intraday precision. This method has been applied to study pharmacokinetics in 12 healty human volunteers.

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LC method for the estimation of Cefprozil in human plazma and its pharmacokinetics

Authors : Shivprakash, Reddy, Dasandi B., Bhat K.M.
Indian Drugs 41(2), February 2004

Abstract:
A new method for the estimation of Cefprozil is developed and validated . This method is simple and rapid because the sample preparation is devoid of any solvent extraction. The plasma proteins were precipitated and the supernatant was directly injected to the HPCL system. The separation was achieved using RP 18e (5µ, 250 * 4 mm) column and the mobile phase was a mixture of Phosphate buffer and acetonitrile. The eluents monitored at 235 nm . The column was maintained at a temperature of 40+ 0.1 oC .The method was validated for sensitivity, specificity precision and accuracy. The LOQ of thid method is 0.25µg ml1 and the calibration curve range is 0.25 to 30µg ml-1. This method is used to study the comparative bioavailability of conventional and sustained release capsules of Cefprozil.

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For copy of the above Publications please contact: drshiv@synchronresearch.com