Browsing by Author "Helmy M.I."

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Liquid chromatography–tandem MS/MS method for simultaneous quantification of paracetamol, chlorzoxazone and aceclofenac in human plasma: An application to a clinical pharmacokinetic study
(John Wiley and Sons Ltd, 2018) Mohamed D.; Hegazy M.A.; Elshahed M.S.; Toubar S.S.; Helmy M.I.; Analytical Chemistry Department; Faculty of Pharmacy; Helwan University; Cairo; Egypt; Pharmaceutical Analytical Chemistry Department; Faculty of Pharmacy; October University for Modern Sciences and Arts; 6 October City; Egypt; Analytical Chemistry Department; Faculty of Pharmacy; Cairo University; Cairo; Egypt
A facile, fast and specific method based on liquid chromatography�tandem mass spectrometry (LC�MS/MS) for the simultaneous quantitation of paracetamol, chlorzoxazone and aceclofenac in human plasma was developed and validated. Sample preparation was achieved by liquid�liquid extraction. The analysis was performed on a reversed-phase C18 HPLC column (5 ?m, 4.6 � 50 mm) using acetonitrile�10 mM ammonium formate pH 3.0 (65:35, v/v) as the mobile phase where atrovastatin was used as an internal standard. A very small injection volume (3 ?L) was applied and the run time was 2.0 min. The detection was carried out by electrospray positive and negative ionization mass spectrometry in the multiple-reaction monitoring mode. The developed method was capable of determining the analytes over the concentration ranges of 0.03�30.0, 0.015�15.00 and 0.15�15.00 ?g/mL for paracetamol, chlorzoxazone and aceclofenac, respectively. Intraday and interday precisions (as coefficient of variation) were found to be ?12.3% with an accuracy (as relative error) of �5.0%. The method was successfully applied to a pharmacokinetic study of the three analytes after being orally administered to six healthy volunteers. Copyright � 2018 John Wiley & Sons, Ltd.
Novel contribution to the simultaneous monitoring of pramipexole dihydrochloride monohydrate and levodopa as co-administered drugs in human plasma utilizing UPLC-MS/MS
(SAGE Publications Ltd, 2018) Mohamed D.; Hegazy M.A.; Elshahed M.S.; Toubar S.S.; Helmy M.I.; Analytical Chemistry Department; Faculty of Pharmacy; Helwan University; Cairo; Egypt; Pharmaceutical Analytical Chemistry Department; Faculty of Pharmacy; October University for Modern Sciences and Arts; 6 October City; Egypt; Analytical Chemistry Department; Faculty of Pharmacy; Cairo University; Cairo; Egypt
An efficient, selective, sensitive, and rapid ultra-performance liquid chromatography tandem mass spectrometry method was established and validated for the quantification of pramipexole dihydrochloride monohydrate and levodopa simultaneously in human plasma with the aid of diphenhydramine as an internal standard. A simple protein precipitation technique with HPLC grade acetonitrile was efficiently utilized for the cleanup of plasma. The analysis was performed using a Hypersil gold 50 mm � 2.1 mm (1.9 �m) column and a mobile phase of 0.2% formic acid and methanol (90: 10 v/v). The triple-quadrupole mass spectrometer equipped with an electrospray source operated in the positive mode was set up in the selective reaction monitoring mode (SRM) to detect the ion transitions m/z 212.15 ?153.01, m/z 198.10? 135.16, and m/z 255.75 ? 166.16 for pramipexole dihydrochloride monohydrate, levodopa, and diphenhydramine, respectively. The method was thoroughly validated according to FDA guidelines and proved to be linear, accurate, and precise over the range 100-4000 pg/mL for pramipexole dihydrochloride monohydrate and 60-4000 ng/mL for levodopa. The proposed method was effectively applied for monitoring both drugs in plasma samples of healthy volunteers. The Author(s) 2018.