Browsing by Author "Elshahed M.S."

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Different mathematical processing of absorption, ratio and derivative spectra for quantification of mixtures containing minor component: An application to the analysis of the recently co-formulated antidiabetic drugs; canagliflozin and metformin
(Elsevier B.V., 2018) Lotfy H.M.; Mohamed D.; Elshahed M.S.; Pharmaceutical Chemistry Department; Faculty of Pharmaceutical Sciences & Pharmaceutical Industries; Future University in Egypt; Cairo; 12311; Egypt; Analytical Chemistry Department; Faculty of Pharmacy; Helwan University; Ein Helwan; Cairo; 11795; Egypt; Pharmaceutical Analytical Chemistry Department; Faculty of Pharmacy; October University for Modern Sciences and Arts11787; Egypt
In the presented work several spectrophotometric methods were performed for the quantification of canagliflozin (CGZ) and metformin hydrochloride (MTF) simultaneously in their binary mixture. Two of these methods; response correlation (RC) and advanced balance point-spectrum subtraction (ABP-SS) were developed and introduced for the first time in this work, where the latter method (ABP-SS) was performed on both the zero order and the first derivative spectra of the drugs. Besides, two recently established methods; advanced amplitude modulation (AAM) and advanced absorbance subtraction (AAS) were also accomplished. All the proposed methods were validated in accordance to the ICH guidelines, where all methods were proved to be accurate and precise. Additionally, the linearity range, limit of detection and limit of quantification were determined and the selectivity was examined through the analysis of laboratory prepared mixtures and the combined dosage form of the drugs. The proposed methods were capable of determining the two drugs in the ratio present in the pharmaceutical formulation CGZ:MTF (1:17) without the requirement of any preliminary separation, further dilution or standard spiking. The results obtained by the proposed methods were in compliance with the reported chromatographic method when compared statistically, proving the absence of any significant difference in accuracy and precision between the proposed and reported methods. � 2017 Elsevier B.V.
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.
The Nile River Microbiome Reveals a Remarkably Stable Community between Wet and Dry Seasons, and Sampling Sites, in a Large Urban Metropolis (Cairo, Egypt)
(Mary Ann Liebert Inc., 2018) Eraqi W.A.; Elrakaiby M.T.; Megahed S.A.; Yousef N.H.; Elshahed M.S.; Yassin A.S.; Department of Microbiology and Immunology; Faculty of Pharmacy; Cairo University; Cairo; Egypt; Department of Microbiology and Immunology; Faculty of Pharmacy; October University for Modern Sciences and Arts (MSA); 6th of October; Giza; Egypt; Department of Microbiology and Molecular Genetics; Oklahoma State University; Stillwater; OK; United States
World freshwater supplies are in need of microbiome diversity analyses as a first step to future ecological studies, and to monitor water safety and quality. The Nile is a major north-flowing river in Africa that displays both spatial and temporal variations in its water quality. Here, we present the first microbiome analysis of the Nile River water in two seasons: (1) summer representing the wet season, and (2) winter representing the dry season, as sampled around Cairo, the capital of Egypt. Surface river water samples were collected from selected locations along the path of river, and the microbial composition was analyzed by next-generation sequencing of the 16S rRNA gene. We found a striking stability in the Nile microbiome community structure along the examined geographical urban sites and between the wet and dry seasons as evidenced by the high proportion of shared operational taxonomic unit values among all samples. The community was dominated by the Cyanobacteria (mainly Synechococcus), Actinobacteria candidate family (ACK-M1), and Proteobacteria (mainly family Comamonadaceae). Among these dominant taxa, Synechococcus exhibited seasonal driven variation in relative abundance. Other taxa were predominantly rare across all seasons and locations, including genera members of which have been implicated as pathogens such as Acinetobacter, Aeromonas, and Legionella. In addition, comparisons with data on freshwater microbiome in other world regions suggest that surface water communities in large rivers exhibit limited variation. Our results offer the first insights on microbial composition in one of the most notable rivers near a large metropolis. � 2018, Mary Ann Liebert, Inc.
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.
Novel univariate spectrophotometric determination of the recently released solid dosage form comprising dapagliflozin and saxagliptin via factorized response spectra: Assessment of the average content and dosage unit uniformity of tablets
(Elsevier B.V., 2019) Lotfy H.M.; Mohamed D.; Elshahed M.S.; Analytical Chemistry Department; Faculty of Pharmacy; Cairo University; Kasr-El Aini Street; Cairo; 11562; Egypt; Pharmaceutical Chemistry Department; Faculty of Pharmaceutical Sciences & Pharmaceutical Industries; Future University in Egypt; Cairo; 11835; Egypt; Analytical Chemistry Department; Faculty of Pharmacy; Helwan University; Ein Helwan; Cairo; 11795; Egypt; Pharmaceutical Analytical Chemistry Department; Faculty of Pharmacy; October University for Modern Sciences and Arts; October City 6; 11787; Egypt
Dapagliflozin (DPF) and saxagliptin (SXG) are currently co-formulated in a tablet dosage form which is prescribed to improve glycemic control. The absorption spectra of DPF and SXG were highly overlapped which completely hindered their simultaneous estimation at their ?max 224 nm and 209 nm, respectively. Thus, in this work three smart and simple univariate spectrophotometric methods were originally established and validated for the first time in order to quantitatively estimate DPF and SXG in bulk forms and in combined pharmaceutical formulation without the requirement for any initial separation or treatment. These methods are; factorized zero order method (FZM), factorized derivative method (FDM) and factorized ratio difference method (FRM). These methods were capable of determining DPF and SXG over the range of 2.5�50.0 ?g/mL and 2.5�60.0 ?g/mL, respectively. All the developed methods are based on a novel and unique approach for the spectral recovery of unresolved spectra named; factorized response spectrum (FRS). The exclusivity of the FRS originates from its ability to completely resolve the cited drugs in the mixture and retrieve their original spectra. Selectivity of all proposed methods was assessed by comparing the obtained results of the mixture analysis with those of the pure powdered drugs. Validation of the newly developed methods was applied as recommended by the ICH demonstrating acceptable accuracy and precision. In general, these methods could be effectively employed for the routine quality control investigation of bulk materials and available market formulations. � 2019 Elsevier B.V.