The Experts below are selected from a list of 9 Experts worldwide ranked by ideXlab platform
Donald S Risley - One of the best experts on this subject based on the ideXlab platform.
-
evaluation of a new pepsin enzyme chiral stationary phase for the optimized separation of Seproxetine s norfluoxetine from r norfluoxetine
Journal of Liquid Chromatography & Related Technologies, 1996Co-Authors: Donald S Risley, Scott V Sharp, John PalmerAbstract:Abstract A thorough analysis of a new commercially available pepsin chiral stationary phase (CSP) has been completed using Seproxetine (S-norfluoxetine) hydrochloride bulk drug substance and R-norfluoxetine hydrochloride as the test analytes. Chromatographic properties of this new Ultron ES-Pepsin column were investigated by varying key mobile phase parameters (pH, flow rate, buffer strength and organic concentration), column temperature and sample loading. After observing and plotting changes in retention, resolution and theoretical plates based on corresponding variation in these parameters, it is possible to choose conditions for the separation that are optimum and robust. The subsequent method validation demonstrated acceptable precision, linearity, recovery, selectivity, limit of detection and ruggedness for the determination of R-norfluoxetine in Seproxetine hydrochloride bulk drug substance.
-
drug excipient interactions of Seproxetine maleate hemi hydrate isothermal stress methods
Drug Development and Industrial Pharmacy, 1993Co-Authors: Sigmund A Schildcrout, Donald S Risley, Rita L KleemannAbstract:Seproxetine maleate hemi-hydrate was originally formulated with pregelatinized starch, to provide 1 and 20 mg free base equivalent gelatin capsule dosage forms for storage at 25°C and 40°C. HPLC analysis after 3 months revealed the formation of a 1,4 Michael addition adduct in each case. No additional degradation products were detected. To pursue a less interactive formulation, 5 mg formulation equivalent mixtures of Seproxetine maleate hemi-hydrate were prepared with pregelatinized starch, lactose, and talc; thus, three distinctly different excipient classifications. These were evaluated in additional isothermal stress experiments at 25°C, 40°C, and 50°C. The results indicated that each excipient interacted with the drug in a unique chemically and thermally dependent manner. Thus, the drug-pregelatinized starch data may be represented by an Arrhenius type relationship, with activation energy of 32 kcal/mol, and formation of the previously described adduct. However, the drug-lactose data suggest reaction ...
John Palmer - One of the best experts on this subject based on the ideXlab platform.
-
evaluation of a new pepsin enzyme chiral stationary phase for the optimized separation of Seproxetine s norfluoxetine from r norfluoxetine
Journal of Liquid Chromatography & Related Technologies, 1996Co-Authors: Donald S Risley, Scott V Sharp, John PalmerAbstract:Abstract A thorough analysis of a new commercially available pepsin chiral stationary phase (CSP) has been completed using Seproxetine (S-norfluoxetine) hydrochloride bulk drug substance and R-norfluoxetine hydrochloride as the test analytes. Chromatographic properties of this new Ultron ES-Pepsin column were investigated by varying key mobile phase parameters (pH, flow rate, buffer strength and organic concentration), column temperature and sample loading. After observing and plotting changes in retention, resolution and theoretical plates based on corresponding variation in these parameters, it is possible to choose conditions for the separation that are optimum and robust. The subsequent method validation demonstrated acceptable precision, linearity, recovery, selectivity, limit of detection and ruggedness for the determination of R-norfluoxetine in Seproxetine hydrochloride bulk drug substance.
Scott V Sharp - One of the best experts on this subject based on the ideXlab platform.
-
evaluation of a new pepsin enzyme chiral stationary phase for the optimized separation of Seproxetine s norfluoxetine from r norfluoxetine
Journal of Liquid Chromatography & Related Technologies, 1996Co-Authors: Donald S Risley, Scott V Sharp, John PalmerAbstract:Abstract A thorough analysis of a new commercially available pepsin chiral stationary phase (CSP) has been completed using Seproxetine (S-norfluoxetine) hydrochloride bulk drug substance and R-norfluoxetine hydrochloride as the test analytes. Chromatographic properties of this new Ultron ES-Pepsin column were investigated by varying key mobile phase parameters (pH, flow rate, buffer strength and organic concentration), column temperature and sample loading. After observing and plotting changes in retention, resolution and theoretical plates based on corresponding variation in these parameters, it is possible to choose conditions for the separation that are optimum and robust. The subsequent method validation demonstrated acceptable precision, linearity, recovery, selectivity, limit of detection and ruggedness for the determination of R-norfluoxetine in Seproxetine hydrochloride bulk drug substance.
Moamen S Refat - One of the best experts on this subject based on the ideXlab platform.
-
solution and solid investigations on the charge transfer complexation between Seproxetine as a selective serotonin reuptake inhibitor drug with six kinds of π electron acceptors
Journal of Molecular Liquids, 2021Co-Authors: Jehan Y Alhumaidi, Moamen S RefatAbstract:Abstract The study in this article deals with the donor–acceptor interaction between Seproxetine (SRX) donor and π–electron acceptors such as picric acid, dinitrobenzene, p-nitro benzoic acid, 2,6-dichloroquinone-4-chloroimide, 2,6-dibromoquinone-4-chloroimide, and 7,7′,8,8′-tetracyanoquinodi methane which can be referred to by the following chemical abbreviations “PA, DNB, p-NBA, DCQ, DBQ, and TCNQ” respectively, in a liquid medium, and the associated complexes in the solid form were also isolated and characterized. A spectrophotometric titration method was employed to the quantitative analyses of Seproxetine HCl in pure form. The stoichiometric analysis based on the molar ratio technique was found to be 1:1 (SRX: π–acceptor) regarding the charge–transfer interactions between the electrons of donor and acceptors. The different physical spectroscopic parameters “formation constant (KCT), molar extinction coefficient (eCT), standard free energy (∆Go), oscillator strength (ƒ), transition dipole moment (μ), resonance energy (RN) and ionization potential (ID)” were calculated according to the spectroscopic data. The charge–transfer complexes which isolated in solid form were well characterized using some of analytical tools “microanalytical, molar conductance, FTIR, 1H-NMR and X-ray powder diffraction”. Thermal stability of solid charge transfer complexes was investigated using TG/DTG thermogravimetric technique. The kinetic thermodynamic values were calculated upon the thermal decomposition diagrams. The surface morphology, particle size and the elementary percentages of the solid SRX charge–transfer complexes were investigated with the help of scanning (SEM) and transmission (TEM) electron microscopies as well as energy-dispersive X-ray spectroscopy (EDX)
Jehan Y Alhumaidi - One of the best experts on this subject based on the ideXlab platform.
-
solution and solid investigations on the charge transfer complexation between Seproxetine as a selective serotonin reuptake inhibitor drug with six kinds of π electron acceptors
Journal of Molecular Liquids, 2021Co-Authors: Jehan Y Alhumaidi, Moamen S RefatAbstract:Abstract The study in this article deals with the donor–acceptor interaction between Seproxetine (SRX) donor and π–electron acceptors such as picric acid, dinitrobenzene, p-nitro benzoic acid, 2,6-dichloroquinone-4-chloroimide, 2,6-dibromoquinone-4-chloroimide, and 7,7′,8,8′-tetracyanoquinodi methane which can be referred to by the following chemical abbreviations “PA, DNB, p-NBA, DCQ, DBQ, and TCNQ” respectively, in a liquid medium, and the associated complexes in the solid form were also isolated and characterized. A spectrophotometric titration method was employed to the quantitative analyses of Seproxetine HCl in pure form. The stoichiometric analysis based on the molar ratio technique was found to be 1:1 (SRX: π–acceptor) regarding the charge–transfer interactions between the electrons of donor and acceptors. The different physical spectroscopic parameters “formation constant (KCT), molar extinction coefficient (eCT), standard free energy (∆Go), oscillator strength (ƒ), transition dipole moment (μ), resonance energy (RN) and ionization potential (ID)” were calculated according to the spectroscopic data. The charge–transfer complexes which isolated in solid form were well characterized using some of analytical tools “microanalytical, molar conductance, FTIR, 1H-NMR and X-ray powder diffraction”. Thermal stability of solid charge transfer complexes was investigated using TG/DTG thermogravimetric technique. The kinetic thermodynamic values were calculated upon the thermal decomposition diagrams. The surface morphology, particle size and the elementary percentages of the solid SRX charge–transfer complexes were investigated with the help of scanning (SEM) and transmission (TEM) electron microscopies as well as energy-dispersive X-ray spectroscopy (EDX)
