The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Keiji Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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insights into atomic level interaction between mefenamic acid and eudragit epo in a Supersaturated Solution by high reSolution magic angle spinning nmr spectroscopy
Molecular Pharmaceutics, 2014Co-Authors: Kenjirou Higashi, Kunikazu Moribe, Keiji Yamamoto, Kazutoshi Yamamoto, Manoj Kumar Pandey, Kamal H Mroue, Ayyalusamy RamamoorthyAbstract:The intermolecular interaction between mefenamic acid (MFA), a poorly water-soluble nonsteroidal anti-inflammatory drug, and Eudragit EPO (EPO), a water-soluble polymer, is investigated in their Supersaturated Solution using high-reSolution magic-angle spinning (HRMAS) nuclear magnetic resonance (NMR) spectroscopy. The stable Supersaturated Solution with a high MFA concentration of 3.0 mg/mL is prepared by dispersing the amorphous solid dispersion into a d-acetate buffer at pH 5.5 and 37 °C. By virtue of MAS at 2.7 kHz, the extremely broad and unresolved (1)H resonances of MFA in one-dimensional (1)H NMR spectrum of the Supersaturated Solution are well-resolved, thus enabling the complete assignment of MFA (1)H resonances in the aqueous Solution. Two-dimensional (2D) (1)H/(1)H nuclear Overhauser effect spectroscopy (NOESY) and radio frequency-driven recoupling (RFDR) under MAS conditions reveal the interaction of MFA with EPO in the Supersaturated Solution at an atomic level. The strong cross-correlations observed in the 2D (1)H/(1)H NMR spectra indicate a hydrophobic interaction between the aromatic group of MFA and the backbone of EPO. Furthermore, the aminoalkyl group in the side chain of EPO forms a hydrophilic interaction, which can be either electrostatic or hydrogen bonding, with the carboxyl group of MFA. We believe these hydrophobic and hydrophilic interactions between MFA and EPO molecules play a key role in the formation of this extremely stable Supersaturated Solution. In addition, 2D (1)H/(1)H RFDR demonstrates that the molecular MFA-EPO interaction is quite flexible and dynamic.
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inhibitory effect of hydroxypropyl methylcellulose acetate succinate on drug recrystallization from a Supersaturated Solution assessed using nuclear magnetic resonance measurements
Molecular Pharmaceutics, 2013Co-Authors: Keisuke Ueda, Kenjirou Higashi, Keiji Yamamoto, Kunikazu MoribeAbstract:We examined the inhibitory effect of hydroxypropyl methylcellulose acetate succinate (HPMC-AS) on drug recrystallization from a Supersaturated Solution using carbamazepine (CBZ) and phenytoin (PHT) as model drugs. HPMC-AS HF grade (HF) inhibited the recrystallization of CBZ more strongly than that by HPMC-AS LF grade (LF). 1D-1H NMR measurements showed that the molecular mobility of CBZ was clearly suppressed in the HF Solution compared to that in the LF Solution. Interaction between CBZ and HF in a Supersaturated Solution was directly detected using nuclear Overhauser effect spectroscopy (NOESY). The cross-peak intensity obtained using NOESY of HF protons with CBZ aromatic protons was greater than that with the amide proton, which indicated that CBZ had hydrophobic interactions with HF in a Supersaturated Solution. In contrast, no interaction was observed between CBZ and LF in the LF Solution. Saturation transfer difference NMR measurement was used to determine the interaction sites between CBZ and HF. S...
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stabilization of a Supersaturated Solution of mefenamic acid from a solid dispersion with eudragit epo
Pharmaceutical Research, 2012Co-Authors: Taro Kojima, Kenjirou Higashi, Toyofumi Suzuki, Kazuo Tomono, Kunikazu Moribe, Keiji YamamotoAbstract:Purpose The stabilization mechanism of a Supersaturated Solution of mefenamic acid (MFA) from a solid dispersion with EUDRAGIT® EPO (EPO) was investigated.
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Stabilization of a Supersaturated Solution of Mefenamic Acid from a Solid Dispersion with EUDRAGIT ® EPO
Pharmaceutical research, 2012Co-Authors: Taro Kojima, Kenjirou Higashi, Toyofumi Suzuki, Kazuo Tomono, Kunikazu Moribe, Keiji YamamotoAbstract:Purpose The stabilization mechanism of a Supersaturated Solution of mefenamic acid (MFA) from a solid dispersion with EUDRAGIT® EPO (EPO) was investigated.
Kenjirou Higashi - One of the best experts on this subject based on the ideXlab platform.
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insights into atomic level interaction between mefenamic acid and eudragit epo in a Supersaturated Solution by high reSolution magic angle spinning nmr spectroscopy
Molecular Pharmaceutics, 2014Co-Authors: Kenjirou Higashi, Kunikazu Moribe, Keiji Yamamoto, Kazutoshi Yamamoto, Manoj Kumar Pandey, Kamal H Mroue, Ayyalusamy RamamoorthyAbstract:The intermolecular interaction between mefenamic acid (MFA), a poorly water-soluble nonsteroidal anti-inflammatory drug, and Eudragit EPO (EPO), a water-soluble polymer, is investigated in their Supersaturated Solution using high-reSolution magic-angle spinning (HRMAS) nuclear magnetic resonance (NMR) spectroscopy. The stable Supersaturated Solution with a high MFA concentration of 3.0 mg/mL is prepared by dispersing the amorphous solid dispersion into a d-acetate buffer at pH 5.5 and 37 °C. By virtue of MAS at 2.7 kHz, the extremely broad and unresolved (1)H resonances of MFA in one-dimensional (1)H NMR spectrum of the Supersaturated Solution are well-resolved, thus enabling the complete assignment of MFA (1)H resonances in the aqueous Solution. Two-dimensional (2D) (1)H/(1)H nuclear Overhauser effect spectroscopy (NOESY) and radio frequency-driven recoupling (RFDR) under MAS conditions reveal the interaction of MFA with EPO in the Supersaturated Solution at an atomic level. The strong cross-correlations observed in the 2D (1)H/(1)H NMR spectra indicate a hydrophobic interaction between the aromatic group of MFA and the backbone of EPO. Furthermore, the aminoalkyl group in the side chain of EPO forms a hydrophilic interaction, which can be either electrostatic or hydrogen bonding, with the carboxyl group of MFA. We believe these hydrophobic and hydrophilic interactions between MFA and EPO molecules play a key role in the formation of this extremely stable Supersaturated Solution. In addition, 2D (1)H/(1)H RFDR demonstrates that the molecular MFA-EPO interaction is quite flexible and dynamic.
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inhibitory effect of hydroxypropyl methylcellulose acetate succinate on drug recrystallization from a Supersaturated Solution assessed using nuclear magnetic resonance measurements
Molecular Pharmaceutics, 2013Co-Authors: Keisuke Ueda, Kenjirou Higashi, Keiji Yamamoto, Kunikazu MoribeAbstract:We examined the inhibitory effect of hydroxypropyl methylcellulose acetate succinate (HPMC-AS) on drug recrystallization from a Supersaturated Solution using carbamazepine (CBZ) and phenytoin (PHT) as model drugs. HPMC-AS HF grade (HF) inhibited the recrystallization of CBZ more strongly than that by HPMC-AS LF grade (LF). 1D-1H NMR measurements showed that the molecular mobility of CBZ was clearly suppressed in the HF Solution compared to that in the LF Solution. Interaction between CBZ and HF in a Supersaturated Solution was directly detected using nuclear Overhauser effect spectroscopy (NOESY). The cross-peak intensity obtained using NOESY of HF protons with CBZ aromatic protons was greater than that with the amide proton, which indicated that CBZ had hydrophobic interactions with HF in a Supersaturated Solution. In contrast, no interaction was observed between CBZ and LF in the LF Solution. Saturation transfer difference NMR measurement was used to determine the interaction sites between CBZ and HF. S...
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stabilization of a Supersaturated Solution of mefenamic acid from a solid dispersion with eudragit epo
Pharmaceutical Research, 2012Co-Authors: Taro Kojima, Kenjirou Higashi, Toyofumi Suzuki, Kazuo Tomono, Kunikazu Moribe, Keiji YamamotoAbstract:Purpose The stabilization mechanism of a Supersaturated Solution of mefenamic acid (MFA) from a solid dispersion with EUDRAGIT® EPO (EPO) was investigated.
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Stabilization of a Supersaturated Solution of Mefenamic Acid from a Solid Dispersion with EUDRAGIT ® EPO
Pharmaceutical research, 2012Co-Authors: Taro Kojima, Kenjirou Higashi, Toyofumi Suzuki, Kazuo Tomono, Kunikazu Moribe, Keiji YamamotoAbstract:Purpose The stabilization mechanism of a Supersaturated Solution of mefenamic acid (MFA) from a solid dispersion with EUDRAGIT® EPO (EPO) was investigated.
Kunikazu Moribe - One of the best experts on this subject based on the ideXlab platform.
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insights into atomic level interaction between mefenamic acid and eudragit epo in a Supersaturated Solution by high reSolution magic angle spinning nmr spectroscopy
Molecular Pharmaceutics, 2014Co-Authors: Kenjirou Higashi, Kunikazu Moribe, Keiji Yamamoto, Kazutoshi Yamamoto, Manoj Kumar Pandey, Kamal H Mroue, Ayyalusamy RamamoorthyAbstract:The intermolecular interaction between mefenamic acid (MFA), a poorly water-soluble nonsteroidal anti-inflammatory drug, and Eudragit EPO (EPO), a water-soluble polymer, is investigated in their Supersaturated Solution using high-reSolution magic-angle spinning (HRMAS) nuclear magnetic resonance (NMR) spectroscopy. The stable Supersaturated Solution with a high MFA concentration of 3.0 mg/mL is prepared by dispersing the amorphous solid dispersion into a d-acetate buffer at pH 5.5 and 37 °C. By virtue of MAS at 2.7 kHz, the extremely broad and unresolved (1)H resonances of MFA in one-dimensional (1)H NMR spectrum of the Supersaturated Solution are well-resolved, thus enabling the complete assignment of MFA (1)H resonances in the aqueous Solution. Two-dimensional (2D) (1)H/(1)H nuclear Overhauser effect spectroscopy (NOESY) and radio frequency-driven recoupling (RFDR) under MAS conditions reveal the interaction of MFA with EPO in the Supersaturated Solution at an atomic level. The strong cross-correlations observed in the 2D (1)H/(1)H NMR spectra indicate a hydrophobic interaction between the aromatic group of MFA and the backbone of EPO. Furthermore, the aminoalkyl group in the side chain of EPO forms a hydrophilic interaction, which can be either electrostatic or hydrogen bonding, with the carboxyl group of MFA. We believe these hydrophobic and hydrophilic interactions between MFA and EPO molecules play a key role in the formation of this extremely stable Supersaturated Solution. In addition, 2D (1)H/(1)H RFDR demonstrates that the molecular MFA-EPO interaction is quite flexible and dynamic.
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inhibitory effect of hydroxypropyl methylcellulose acetate succinate on drug recrystallization from a Supersaturated Solution assessed using nuclear magnetic resonance measurements
Molecular Pharmaceutics, 2013Co-Authors: Keisuke Ueda, Kenjirou Higashi, Keiji Yamamoto, Kunikazu MoribeAbstract:We examined the inhibitory effect of hydroxypropyl methylcellulose acetate succinate (HPMC-AS) on drug recrystallization from a Supersaturated Solution using carbamazepine (CBZ) and phenytoin (PHT) as model drugs. HPMC-AS HF grade (HF) inhibited the recrystallization of CBZ more strongly than that by HPMC-AS LF grade (LF). 1D-1H NMR measurements showed that the molecular mobility of CBZ was clearly suppressed in the HF Solution compared to that in the LF Solution. Interaction between CBZ and HF in a Supersaturated Solution was directly detected using nuclear Overhauser effect spectroscopy (NOESY). The cross-peak intensity obtained using NOESY of HF protons with CBZ aromatic protons was greater than that with the amide proton, which indicated that CBZ had hydrophobic interactions with HF in a Supersaturated Solution. In contrast, no interaction was observed between CBZ and LF in the LF Solution. Saturation transfer difference NMR measurement was used to determine the interaction sites between CBZ and HF. S...
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stabilization of a Supersaturated Solution of mefenamic acid from a solid dispersion with eudragit epo
Pharmaceutical Research, 2012Co-Authors: Taro Kojima, Kenjirou Higashi, Toyofumi Suzuki, Kazuo Tomono, Kunikazu Moribe, Keiji YamamotoAbstract:Purpose The stabilization mechanism of a Supersaturated Solution of mefenamic acid (MFA) from a solid dispersion with EUDRAGIT® EPO (EPO) was investigated.
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Stabilization of a Supersaturated Solution of Mefenamic Acid from a Solid Dispersion with EUDRAGIT ® EPO
Pharmaceutical research, 2012Co-Authors: Taro Kojima, Kenjirou Higashi, Toyofumi Suzuki, Kazuo Tomono, Kunikazu Moribe, Keiji YamamotoAbstract:Purpose The stabilization mechanism of a Supersaturated Solution of mefenamic acid (MFA) from a solid dispersion with EUDRAGIT® EPO (EPO) was investigated.
Shen Chih Lee - One of the best experts on this subject based on the ideXlab platform.
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Effect of ultrasonic waves on crystallization from a Supersaturated Solution of alum
Journal of Materials Science, 1992Co-Authors: Naoya Enomoto, Tae Hyun Sung, Zenbe E. Nakagawa, Shen Chih LeeAbstract:The effect of ultrasonic waves on the particle size and distribution of precipitated crystals from a slowly cooled Supersaturated Solution of ammonium aluminium sulphate hydrate was investigated. It was found that ultrasonic irradiation greatly promoted the homogeneity in particle sizes of the crystals precipitated. Average particle sizes of both the mechanical stirred and the ultrasonically treated samples did not change much if the initial solute concentration was beyond the saturation solubility of the Solution. The higher acoustic intensity of the higher frequency ultrasonic transducer resulted in a larger average particle size in the recrystallization process.
A. E. Kuchma - One of the best experts on this subject based on the ideXlab platform.
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Gas bubble growth dynamics in a Supersaturated Solution: Henry's and Sievert's solubility laws
arXiv: Chemical Physics, 2009Co-Authors: A. E. Kuchma, Gennady Y. Gor, F M KuniAbstract:Theoretical description of diffusion growth of a gas bubble after its nucleation in Supersaturated liquid Solution is p resented. We study the influence of Laplace pressure on the bubble growt h. We consider two different solubility laws: Henry’s law, whi ch is fulfilled for the systems where no gas molecules dissociat ion takes place and Sievert’s law, which is fulfilled for the syst ems where gas molecules completely dissociate in the solvent into two parts. We show that the difference between Henry’s and Sievert’s laws for chemical equilibrium conditions causes the difference in bubble growth dynamics. Assuming that diffusion flux of dissolved gas molecules to the bubble is steady we obtain differential equations on bubble radius for both solubility la ws. For the case of homogeneous nucleation of a bubble, which takes place at a significant pressure drop bubble dynamics equatio ns for Henry’s and Sievert’s laws are solved analytically. For both solubility laws three characteristic stages of bubble grow th are marked out. Intervals of bubble size change and time intervals of these stages are found. We also obtain conditions of diffusion flux steadiness corresponding to consecutive stages. The fu lfillment of these conditions is discussed for the case of nucleation of water vapor bubbles in magmatic melts. For Sievert’s law the analytical treatment of the problem of bubble disSolution in a pure solvent is also presented.
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dynamics of gas bubble growth in a Supersaturated Solution with sievert s solubility law
Journal of Chemical Physics, 2009Co-Authors: A. E. KuchmaAbstract:This paper presents a theoretical description of diffusion growth of a gas bubble after its nucleation in Supersaturated liquid Solution. We study systems where gas molecules completely dissociate in the solvent into two parts, thus making Sievert’s solubility law valid. We show that the difference between Henry’s and Sievert’s laws for chemical equilibrium conditions causes the difference in bubble growth dynamics. Assuming that diffusion flux is steady we obtain a differential equation on bubble radius. Bubble dynamics equation is solved analytically for the case of homogeneous nucleation of a bubble, which takes place at a significant pressure drop. We also obtain conditions of diffusion flux steadiness. The fulfillment of these conditions is studied for the case of nucleation of water vapor bubbles in magmatic melts.
