Sayed Mohamed Derayea

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Although cytochromes P450 2C9 (CYP2C9) and 2C19 (CYP2C19) have 91% amino acid identity, they have different substrate specificities. Previous studies have suggested that several amino acid residues may be involved in substrate specificity. In this study, we focused on the roles of two amino acids, residues 72 and 241. The amino acids in these positions have(More)
The investigation of cytochrome P450 (CYP) mediated metabolism reactions by determination of enzyme kinetic parameters, Michaelis constant (K(m)), maximum reaction velocity (V(max)), and intrinsic clearance (CL(int)) is important aspects in discovery and development of drugs. The kinetic parameters can be used to predict the clearance prior to human(More)
A new validated spectrofluorimetric method has been developed for the determination of some cephalosporins namely; cefepime, cefaclor, cefadroxil, cefpodoxime and cefexime. The method was based on the reaction of these drugs with safranin in slightly alkaline medium (pH 8.0), to form ion-association complexes. The fluorescent products were extracted into(More)
A new sensitive and discriminating spectrofluorimetric method has been developed and validated for determination of Lisinopril, one of the angiotensin converting enzyme inhibitors, in its pure bulk form and pharmaceutical tablets. The reaction of Lisinopril with ethylacetoacetate and formaldehyde in acidic buffered medium (pH3.8) has yielded a pale yellow(More)
A validated simple and selective spectrophotometric method was developed for the selective determination of amlodipine and nicardipine in bulk powders and pharmaceutical formulation. The proposed method was based on the formulation of a binary complex between either of the studied drugs and eosin Y in aqueous buffered medium. The surfactant,(More)
Two simple, selective and accurate methods were developed for the determination of Labetalol hydrochloride in pure form and pharmaceutical tablets. Both methods are based on derivatization of the studied drug with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBDCl) in alkaline medium (pH7.5).The reaction product was measured spectrofluorimetrically at 540nm(More)
A selective and new spectrophotometric method is described for determination of five 1,4-dihydropyridine drugs (1,4DHP); namely nifedipine (NIF), nicardipine (NIC), nimodipine (NIM), felodipine (FEL) and amlodipine (AML). The method is based on a coupling reaction between the cited drugs and vanillin reagent in acidic condition. Under optimized conditions,(More)
New, sensitive, and selective spectrofluorimetric method was developed for determination of three aminoglycoside drugs in different dosage forms, namely; neomycin sulfate (NEO), tobramycin (TOB) and kanamycin sulfate (KAN). The method is based on Hantzsch condensation reaction between the primary amino group of aminoglycosides with acetylacetone and(More)
A novel, sensitive and selective spectrofluorimetric method has been developed and validated for determination of silodosine (SLD) in its dosage form and human plasma. The method is based on nucleophilic substitution reaction of SLD with 5-(dimethylamino) naphthalene-1-sulfonyl chloride (dansyl chloride) in presence of 5.0 × 10−4 M sodium carbonate (pH(More)
A newly developed thin-layer chromatographic (TLC) method coupled with fluorescence detection for specific determination of Febuxostat (FEB) was designed. The proposed method adopts exposure of FEB on a developed TLC plate to hydrochloric acid vapors, resulting in a large enhancement of its weak fluorescence, permitting its specific and sensitive(More)