The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Hoo-kyun Choi - One of the best experts on this subject based on the ideXlab platform.
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enhanced bioavailability of Piroxicam via salt formation with ethanolamines
International Journal of Pharmaceutics, 2005Co-Authors: Hyesun Gwak, Junshik Choi, Hoo-kyun ChoiAbstract:Abstract Piroxicam can be ionized as a zwitterion that has two pKa values (pKa1 = 1.86 and pKa2 = 5.46). Consequently, Piroxicam has a low solubility in both polar and nonpolar media, and a low lipophilicity, which results in a low permeability. Three Piroxicam-ethanolamine salts were prepared, which had a higher area under the curve (AUC) than Piroxicam. There were minimal differences in the AUC among the salt forms. It was reported that the Piroxicam triethanolamine salt had a lower permeability across the skin than Piroxicam but it had a higher oral bioavailability. Piroxicam monoethanolamine showed the highest Cmax followed by Piroxicam diethanolamine and Piroxicam triethanolamine. The dissolution rates of Piroxicam and its salts were similar at pH 1.2. Piroxicam monoethanolamine showed the highest dissolution rate at pH 6.8, which was followed by the Piroxicam diethanolamine and Piroxicam triethanolamine salts. The order of dissolution rate at pH 6.8 matched the order of Cmax or the AUC after oral administration.
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enhanced percutaneous absoption of Piroxicam via salt formation with ethanolamines
Pharmaceutical Research, 2002Co-Authors: Hyun-ah Cheong, Hoo-kyun ChoiAbstract:Purpose. The aim of this work was to prepare Piroxicam-ethanolamine salts (PX-EAs) with improved physicochemical properties for transdermal application. Methods. The physicochemical properties of prepared salts were investigated by DSC and FT-IR. Their percutaneous absorption characteristics across hairless mouse skin and the effect of various enhancers were studied using a flow-through diffusion cell system. Results. Three Piroxicam-ethanolamine salts were prepared. Piroxicam monoethanolamine salt (PX-MEA) and Piroxicam diethanolamine salt (PX-DEA) had higher solubility than Piroxicam in most of vehicles tested and a higher permeation rate across the skin. The solubility and permeation rate of Piroxicam triethanolamine salt (PX-TEA) was lower than those of Piroxicam in most of vehicles tested. However, there was no significant change in octanol/water partition coefficient by salt formation. Salt formation lowered the melting point of Piroxicam and, of the systems examined, PX-DEA showed the lowest melting point. When the effect of various enhancers were evaluated, nonionic surfactants having medium HLB, an alkyl chain length of C18 and an ethylene oxide chain were better able to modify the permeability of the stratum corneum and to promote the effective penetration of Piroxicam and PX-EAs. Conclusions. Piroxicam salt formation with MEA and DEA improved the physicochemical properties and enhanced the skin permeability of Piroxicam.
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Enhanced Percutaneous Absorption of Piroxicam via Salt Formation with Ethanolamines
Pharmaceutical Research, 2002Co-Authors: Hyun-ah Cheong, Hoo-kyun ChoiAbstract:Purpose . The aim of this work was to prepare Piroxicam-ethanolamine salts (PX-EAs) with improved physicochemical properties for transdermal application. Methods . The physicochemical properties of prepared salts were investigated by DSC and FT-IR. Their percutaneous absorption characteristics across hairless mouse skin and the effect of various enhancers were studied using a flow-through diffusion cell system. Results . Three Piroxicam-ethanolamine salts were prepared. Piroxicam monoethanolamine salt (PX-MEA) and Piroxicam diethanolamine salt (PX-DEA) had higher solubility than Piroxicam in most of vehicles tested and a higher permeation rate across the skin. The solubility and permeation rate of Piroxicam triethanolamine salt (PX-TEA) was lower than those of Piroxicam in most of vehicles tested. However, there was no significant change in octanol/water partition coefficient by salt formation. Salt formation lowered the melting point of Piroxicam and, of the systems examined, PX-DEA showed the lowest melting point. When the effect of various enhancers were evaluated, nonionic surfactants having medium HLB, an alkyl chain length of C18 and an ethylene oxide chain were better able to modify the permeability of the stratum corneum and to promote the effective penetration of Piroxicam and PX-EAs. Conclusions . Piroxicam salt formation with MEA and DEA improved the physicochemical properties and enhanced the skin permeability of Piroxicam.
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Permeation of Piroxicam from the Poloxamer Gels
Drug Development and Industrial Pharmacy, 1999Co-Authors: Sang-chul Shin, Hoo-kyun ChoiAbstract:Topical formulations of Piroxicam were prepared using poloxamer 407 or poloxamer 188 by a cold method, and the permeation characteristics of Piroxicam were evaluated. The permeation rate of Piroxicam across the synthetic cellulose membrane and the rat skin decreased as the concentration of poloxamer increased. Though poloxamer gel exhibits reversed thermal behavior, the permeation rate of Piroxicam increased with increasing temperature, indicating that the diffusional pathway of Piroxicam is a water channel within the gel formulation. The pH of the gel did not affect the permeation rate of Piroxicam significantly. As the concentration of Piroxicam in the gel formulation increased, the permeation rate of Piroxicam increased up to 1% and reached a plateau above 1%. Among various enhancers tested, polyoxyethylene-2-oleyl ether showed the highest enhancing effect, with an enhancement ratio of 2.84. Based on experimental results, the permeation rate of Piroxicam can be controlled by changing the poloxamer conc...
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Permeation of Piroxicam from the poloxamer gels
Drug development and industrial pharmacy, 1999Co-Authors: Sang-chul Shin, Cheong-weon Cho, Hoo-kyun ChoiAbstract:Topical formulations of Piroxicam were prepared using poloxamer 407 or poloxamer 188 by a cold method, and the permeation characteristics of Piroxicam were evaluated. The permeation rate of Piroxicam across the synthetic cellulose membrane and the rat skin decreased as the concentration of poloxamer increased. Though poloxamer gel exhibits reversed thermal behavior, the permeation rate of Piroxicam increased with increasing temperature, indicating that the diffusional pathway of Piroxicam is a water channel within the gel formulation. The pH of the gel did not affect the permeation rate of Piroxicam significantly. As the concentration of Piroxicam in the gel formulation increased, the permeation rate of Piroxicam increased up to 1% and reached a plateau above 1%. Among various enhancers tested, polyoxyethylene-2-oleyl ether showed the highest enhancing effect, with an enhancement ratio of 2.84. Based on experimental results, the permeation rate of Piroxicam can be controlled by changing the poloxamer concentration or drug concentration and by the addition of an appropriate enhancer.
Panida Vayumhasuwan - One of the best experts on this subject based on the ideXlab platform.
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Viscoelastic Properties of Carbopol 940 Gels and Their Relationships to Piroxicam Diffusion Coefficients in Gel Bases
Pharmaceutical Research, 2005Co-Authors: Rathapon A-sasutjarit, Anuvat Sirivat, Panida VayumhasuwanAbstract:Purpose This study was conducted to determine the effect of formula compositions on viscoelastic properties of Piroxicam gels using Carbopol 940 as a gelling agent and to determine the relationships between viscoelastic properties of Carbopol 940 gel bases and diffusion coefficients of Piroxicam in gel bases. Methods Piroxicam gels (1.0% w/w) were prepared by using Carbopol 940 as a gelling agent and varying Carbopol 940 concentrations, glycerin, and sodium chloride contents. The in vitro release of Piroxicam from gel bases to the receiving media, isotonic phosphate buffer solution (pH 7.4), were carried out using Franz-modified cell. The Piroxicam diffusion coefficients were obtained by Higuchi's equation. Rheological property measurements of gel samples were performed via a cone and plate fluid rheometer. Relationships between viscoelastic properties of gel samples and Piroxicam diffusion in gel bases were analyzed by Pearson's test at a p value of less than 0.05. Results All Piroxicam gels exhibited predominantly elastic solid behavior whose magnitude depended on Carbopol 940 concentration. Preparations containing good solvent exhibited more elastic solid characters. In contrast, the Piroxicam gels containing higher sodium chloride contents possessed more viscous fluid behavior. Analyzed by Pearson's test at a p value of less than 0.05, Piroxicam diffusion coefficients were directly proportional to loss tangent, but were inversely proportional to storage modulus, loss modulus, complex modulus, and viscosity. Conclusions There is a potential for predicting drug diffusion coefficients from their correlations to rheological parameters. This could be beneficial to the formulation design of transdermal drug delivery systems including mucoadhesive drug delivery systems.
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viscoelastic properties of carbopol 940 gels and their relationships to Piroxicam diffusion coefficients in gel bases
Pharmaceutical Research, 2005Co-Authors: Rathapon Asasutjarit, Anuvat Sirivat, Panida VayumhasuwanAbstract:This study was conducted to determine the effect of formula compositions on viscoelastic properties of Piroxicam gels using Carbopol 940 as a gelling agent and to determine the relationships between viscoelastic properties of Carbopol 940 gel bases and diffusion coefficients of Piroxicam in gel bases. Piroxicam gels (1.0% w/w) were prepared by using Carbopol 940 as a gelling agent and varying Carbopol 940 concentrations, glycerin, and sodium chloride contents. The in vitro release of Piroxicam from gel bases to the receiving media, isotonic phosphate buffer solution (pH 7.4), were carried out using Franz-modified cell. The Piroxicam diffusion coefficients were obtained by Higuchi's equation. Rheological property measurements of gel samples were performed via a cone and plate fluid rheometer. Relationships between viscoelastic properties of gel samples and Piroxicam diffusion in gel bases were analyzed by Pearson's test at a p value of less than 0.05. All Piroxicam gels exhibited predominantly elastic solid behavior whose magnitude depended on Carbopol 940 concentration. Preparations containing good solvent exhibited more elastic solid characters. In contrast, the Piroxicam gels containing higher sodium chloride contents possessed more viscous fluid behavior. Analyzed by Pearson's test at a p value of less than 0.05, Piroxicam diffusion coefficients were directly proportional to loss tangent, but were inversely proportional to storage modulus, loss modulus, complex modulus, and viscosity. There is a potential for predicting drug diffusion coefficients from their correlations to rheological parameters. This could be beneficial to the formulation design of transdermal drug delivery systems including mucoadhesive drug delivery systems.
Sang-cheol Chi - One of the best experts on this subject based on the ideXlab platform.
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Transdermal delivery of Piroxicam using microemulsions
Archives of Pharmacal Research, 2005Co-Authors: Eun-seok Park, Bum Jin Yun, In Ja Ko, Yu Cui, Sang-cheol ChiAbstract:To improve the skin permeability of Piroxicam, a new oil-in-water microemulsion containing 0.5% Piroxicam was developed. Among various oils investigated for their suitability as an oil phase for the microemulsion system, oleic acid showed both excellent solubility and skin permeation enhancing effect for Piroxicam. Microemulsion existence ranges were identified through the construction of the pseudo-ternary phase diagram. The effect of the content of oleic acid and the ratio of the surfactant/cosurfactant on skin permeation of Piroxicam were evaluated with excised rat skins. The optimum formulation with the highest skin permeation rate (47.14 μg/cm2/h) consisted of 0.5% Piroxicam, 10% oleic acid, 60% Labrasol/ethanol (1:5) and water.
David J.w. Grant - One of the best experts on this subject based on the ideXlab platform.
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mechanochromism of Piroxicam accompanied by intermolecular proton transfer probed by spectroscopic methods and solid phase changes
Journal of the American Chemical Society, 2005Co-Authors: Agam R. Sheth, Francis X. Muller, Joseph W Lubach, Eric J Munson, David J.w. GrantAbstract:Structural and solid-state changes of Piroxicam in its crystalline form under mechanical stress were investigated using cryogenic grinding, powder X-ray diffractometry, diffuse-reflectance solid-state ultraviolet-visible spectroscopy, variable-temperature solid-state (13)C nuclear magnetic resonance spectroscopy, and solid-state diffuse-reflectance infrared Fourier transform spectroscopy. Crystalline Piroxicam anhydrate exists as colorless single crystals irrespective of the polymorphic form and contains neutral Piroxicam molecules. Under mechanical stress, these crystals become yellow amorphous Piroxicam, which has a strong propensity to recrystallize to a colorless crystalline phase. The yellow color of amorphous Piroxicam is attributed to charged Piroxicam molecules. Variable-temperature solid-state (13)C NMR spectroscopy indicates that most of the amorphous Piroxicam consists of neutral Piroxicam molecules; the charged species comprise only about 8% of the amorphous phase. This ability to quantify the fractions of charged and neutral molecules of Piroxicam in the amorphous phase highlights the unique capability of solid-state NMR to quantify mixtures in the absence of standards. Other compounds of Piroxicam, which are yellow, are known to contain zwitterionic Piroxicam molecules. The present work describes a system in which proton transfer accompanies both solid-state disorder and a change in color induced by mechanical stress, a phenomenon which may be termed mechanochromism of Piroxicam.
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Communications Polymorphism in Piroxicam
2004Co-Authors: Agam R. Sheth, Simon Bates, Francis X. Muller, David J.w. GrantAbstract:Piroxciam is a polymorphic drug. However, reports on the number and nomenclature of the polymorphs of Piroxicam and the complete hydrogen-bonding patterns of Piroxicam molecules in the crystal forms are in conflict and are sources of confusion, which we attempt to clarify. The difference in energy of the two polymorphs, I and II, of Piroxicam arises predominantly from the difference between their lattice energies, rather than between their conformational energies. The detailed hydrogen-bonding networks of the two polymorphs are described and compared. Despite stabilization of the polymorphs by hydrogen bonds, a loss of polymorphic memory was observed upon cryogrinding the two polymorphs, leading to differences in recrystallization behavior between amorphous Piroxicam prepared from polymorphs I and II.
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Polymorphism in Piroxicam
Crystal Growth & Design, 2004Co-Authors: Agam R. Sheth, Simon Bates, Francis X. Muller, David J.w. GrantAbstract:Piroxciam is a polymorphic drug. However, reports on the number and nomenclature of the polymorphs of Piroxicam and the complete hydrogen-bonding patterns of Piroxicam molecules in the crystal forms are in conflict and are sources of confusion, which we attempt to clarify. The difference in energy of the two polymorphs, I and II, of Piroxicam arises predominantly from the difference between their lattice energies, rather than between their conformational energies. The detailed hydrogen-bonding networks of the two polymorphs are described and compared. Despite stabilization of the polymorphs by hydrogen bonds, a loss of polymorphic memory was observed upon cryogrinding the two polymorphs, leading to differences in recrystallization behavior between amorphous Piroxicam prepared from polymorphs I and II.
Eun-seok Park - One of the best experts on this subject based on the ideXlab platform.
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Transdermal delivery of Piroxicam using microemulsions
Archives of Pharmacal Research, 2005Co-Authors: Eun-seok Park, Bum Jin Yun, In Ja Ko, Yu Cui, Sang-cheol ChiAbstract:To improve the skin permeability of Piroxicam, a new oil-in-water microemulsion containing 0.5% Piroxicam was developed. Among various oils investigated for their suitability as an oil phase for the microemulsion system, oleic acid showed both excellent solubility and skin permeation enhancing effect for Piroxicam. Microemulsion existence ranges were identified through the construction of the pseudo-ternary phase diagram. The effect of the content of oleic acid and the ratio of the surfactant/cosurfactant on skin permeation of Piroxicam were evaluated with excised rat skins. The optimum formulation with the highest skin permeation rate (47.14 μg/cm2/h) consisted of 0.5% Piroxicam, 10% oleic acid, 60% Labrasol/ethanol (1:5) and water.