The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Kenji Sugibayashi - One of the best experts on this subject based on the ideXlab platform.
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analysis of hair follicle penetration of lidocaine and fluorescein isothiocyanate dextran 4 kda using hair follicle plugging method
Drug Development and Industrial Pharmacy, 2014Co-Authors: Daisuke Horita, Hiroaki Todo, Masato Yoshimoto, Kenji SugibayashiAbstract:AbstractObjective: Skin appendages including hair follicles (hfs) and the stratum corneum (sc) are beginning to be recognized as important Permeation pathways for the skin Permeation of drugs, but their detailed role is not yet clear. To investigate the contribution of hfs to drug Permeation, we conducted skin Permeation tests by controlling the hf contribution with a hf-plugging method.Method: Lidocaine (LC) and fluorescein isothiocyanate-dextran 4 kDa (FD-4) were selected as model drugs and pig ear skin was used as model skin.Results: Skin permeabilities of ionized LC and FD-4 decreased with hf-plugging, whereas no change was observed for the skin Permeation of unionized LC. A fairly good correlation was found for ionized LC and FD-4 between skin permeability and the number of hfs plugged. Permeation parameters of model drugs for both skin pathways were calculated utilizing Fick's second law of diffusion. Consequently, the sc pathway could highly contribute to the Permeation of unionized LC, since union...
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Mathematical model to predict skin concentration after topical application of drugs
Pharmaceutics, 2013Co-Authors: Hiroaki Todo, Wesam R. Kadhum, Takeshi Oshizaka, Kenji SugibayashiAbstract:Skin Permeation experiments have been broadly done since 1970s to 1980s as an evaluation method for transdermal drug delivery systems. In topically applied drug and cosmetic formulations, skin concentration of chemical compounds is more important than their skin Permeations, because primary target site of the chemical compounds is skin surface or skin tissues. Furthermore, the direct pharmacological reaction of a metabolically stable drug that binds with specific receptors of known expression levels in an organ can be determined by Hill's equation. Nevertheless, little investigation was carried out on the test method of skin concentration after topically application of chemical compounds. Recently we investigated an estimating method of skin concentration of the chemical compounds from their skin Permeation profiles. In the study, we took care of "3Rs" issues for animal experiments. We have proposed an equation which was capable to estimate animal skin concentration from Permeation profile through the artificial membrane (silicone membrane) and animal skin. This new approach may allow the skin concentration of a drug to be predicted using Fick's second law of diffusion. The silicone membrane was found to be useful as an alternative membrane to animal skin for predicting skin concentration of chemical compounds, because an extremely excellent extrapolation to animal skin concentration was attained by calculation using the silicone membrane Permeation data. In this chapter, we aimed to establish an accurate and convenient method for predicting the concentration profiles of drugs in the skin based on the skin Permeation parameters of topically active drugs derived from steady-state skin Permeation experiments. © 2013 by the authors; licensee MDPI, Basel, Switzerland.
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Effect of Direction (Epidermis-To-Dermis and Dermis-To-Epidermis) on the Permeation of Several Chemical Compounds through Full-Thickness Skin and Stripped Skin
Pharmaceutical Research, 2012Co-Authors: Takeshi Oshizaka, Hiroaki Todo, Kenji SugibayashiAbstract:ABSTRACTPurposeCompound Permeation through stratum corneum-stripped skin is generally greater than that through full-thickness skin. In addition, epidermis-to-dermis Permeation profile should be the same as dermis-to-epidermis Permeation profile. However, stripped skin permeability of some compounds was lower than full-thickness skin permeability and different permeabilities were found for some compounds between the two directions of skin Permeation. The reasons for these findings were investigated in this study.MethodsFull-thickness or stripped hairless rat skin was set in a Franz-type diffusion cell, and a solution of compound was applied on the epidermis or dermis side to determine the in vitro skin permeability.ResultsAlthough the stripped skin permeability of pentyl paraben (PeP) with extremely high log K _ o/w was lower than full-thickness skin permeabilities, the addition of 3% ethanol resulted in the expected Permeation order. Epidermis-to-dermis Permeation of PeP through full-thickness skin was higher than dermis-to-epidermis Permeation. Epidermis-to-dermis Permeations of fluorescein isothiocyanate dextran (FD-4) and isosorbide 5-mononitrate with negative log K _ o/w were also higher than those in the opposite direction.ConclusionsMorphological observation of skin after FD-4 Permeation suggested that a conically shaped trans-follicular Permeation pathway model could be advocated to explain the difference between the epidermis-to-dermis Permeation and that in the opposite direction.
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effect of several electrolyzed waters on the skin Permeation of lidocaine benzoic acid and isosorbide mononitrate
Drug Development and Industrial Pharmacy, 2009Co-Authors: Toshihiko Kitamura, Hiroaki Todo, Kenji SugibayashiAbstract:The effects of several electrolyzed waters were evaluated on the Permeation of model base, acid and non-ionized compounds, lidocaine (LC), benzoic acid (BA), and isosorbide mononitrate (ISMN), respectively, through excised hairless rat skin. Strong alkaline-electrolyzed reducing water (ERW) enhanced and suppressed the skin Permeation of LC and BA, respectively, and it also increased the skin Permeation of ISMN, a non-ionized compound. On the contrary, strong acidic electrolyzed oxidizing water (EOW) enhanced BA Permeation, whereas suppressing LC Permeation. Only a marginal effect was observed on the skin Permeation of ISMN by EOW. These marked enhancing effects of ERW on the skin Permeation of LC and ISMN were explained by pH partition hypothesis as well as a decrease in skin impedance. The present results strongly support that electrolyzed waters, ERW and EOW, can be used as a new vehicle in topical pharmaceuticals or cosmetics to modify the skin Permeation of drugs without severe skin damage.
David R. Friend - One of the best experts on this subject based on the ideXlab platform.
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In vitro skin Permeation techniques
Journal of Controlled Release, 1992Co-Authors: David R. FriendAbstract:This paper reviews various techniques used to assess Permeation of drugs into and through skin under in vitro conditions. There have been a wide variety of diffusion cells designed for in vitro measurement of skin Permeation. These cells have generally been designed in one of two ways: side-by-side (bichambers) and vertical in vivo mimic diffusion cells. A primary goal of in vitro Permeation studies is the prediction of skin Permeation in vivo, in this regard, side-by-side diffusional cells are useful in delineating mechanisms of Permeation under controlled conditions, but are of more limited usefulness in predicting skin Permeation in vivo. Vertical cells are more versatile because a wide variety of experimental conditions can be used to gain information useful in the evaluation of formulations ultimately destined for clinical use. A number of diffusion cell designs are reviewed and some of their advantages and disadvantages are discussed. In addition to diffusion cells used to assess passive diffusion, iontophoretic- and phonophoretic-enhanced skin Permeation in vitro is also considered. Until the use of differentiated keratinocytes in culture becomes inexpensive and the relationships between skin Permeation in vitro and in vivo are established, skin permeability will be measured using excised animal or human skin in diffusion cells. © 1992.
Hiroaki Todo - One of the best experts on this subject based on the ideXlab platform.
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analysis of hair follicle penetration of lidocaine and fluorescein isothiocyanate dextran 4 kda using hair follicle plugging method
Drug Development and Industrial Pharmacy, 2014Co-Authors: Daisuke Horita, Hiroaki Todo, Masato Yoshimoto, Kenji SugibayashiAbstract:AbstractObjective: Skin appendages including hair follicles (hfs) and the stratum corneum (sc) are beginning to be recognized as important Permeation pathways for the skin Permeation of drugs, but their detailed role is not yet clear. To investigate the contribution of hfs to drug Permeation, we conducted skin Permeation tests by controlling the hf contribution with a hf-plugging method.Method: Lidocaine (LC) and fluorescein isothiocyanate-dextran 4 kDa (FD-4) were selected as model drugs and pig ear skin was used as model skin.Results: Skin permeabilities of ionized LC and FD-4 decreased with hf-plugging, whereas no change was observed for the skin Permeation of unionized LC. A fairly good correlation was found for ionized LC and FD-4 between skin permeability and the number of hfs plugged. Permeation parameters of model drugs for both skin pathways were calculated utilizing Fick's second law of diffusion. Consequently, the sc pathway could highly contribute to the Permeation of unionized LC, since union...
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Mathematical model to predict skin concentration after topical application of drugs
Pharmaceutics, 2013Co-Authors: Hiroaki Todo, Wesam R. Kadhum, Takeshi Oshizaka, Kenji SugibayashiAbstract:Skin Permeation experiments have been broadly done since 1970s to 1980s as an evaluation method for transdermal drug delivery systems. In topically applied drug and cosmetic formulations, skin concentration of chemical compounds is more important than their skin Permeations, because primary target site of the chemical compounds is skin surface or skin tissues. Furthermore, the direct pharmacological reaction of a metabolically stable drug that binds with specific receptors of known expression levels in an organ can be determined by Hill's equation. Nevertheless, little investigation was carried out on the test method of skin concentration after topically application of chemical compounds. Recently we investigated an estimating method of skin concentration of the chemical compounds from their skin Permeation profiles. In the study, we took care of "3Rs" issues for animal experiments. We have proposed an equation which was capable to estimate animal skin concentration from Permeation profile through the artificial membrane (silicone membrane) and animal skin. This new approach may allow the skin concentration of a drug to be predicted using Fick's second law of diffusion. The silicone membrane was found to be useful as an alternative membrane to animal skin for predicting skin concentration of chemical compounds, because an extremely excellent extrapolation to animal skin concentration was attained by calculation using the silicone membrane Permeation data. In this chapter, we aimed to establish an accurate and convenient method for predicting the concentration profiles of drugs in the skin based on the skin Permeation parameters of topically active drugs derived from steady-state skin Permeation experiments. © 2013 by the authors; licensee MDPI, Basel, Switzerland.
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Effect of Direction (Epidermis-To-Dermis and Dermis-To-Epidermis) on the Permeation of Several Chemical Compounds through Full-Thickness Skin and Stripped Skin
Pharmaceutical Research, 2012Co-Authors: Takeshi Oshizaka, Hiroaki Todo, Kenji SugibayashiAbstract:ABSTRACTPurposeCompound Permeation through stratum corneum-stripped skin is generally greater than that through full-thickness skin. In addition, epidermis-to-dermis Permeation profile should be the same as dermis-to-epidermis Permeation profile. However, stripped skin permeability of some compounds was lower than full-thickness skin permeability and different permeabilities were found for some compounds between the two directions of skin Permeation. The reasons for these findings were investigated in this study.MethodsFull-thickness or stripped hairless rat skin was set in a Franz-type diffusion cell, and a solution of compound was applied on the epidermis or dermis side to determine the in vitro skin permeability.ResultsAlthough the stripped skin permeability of pentyl paraben (PeP) with extremely high log K _ o/w was lower than full-thickness skin permeabilities, the addition of 3% ethanol resulted in the expected Permeation order. Epidermis-to-dermis Permeation of PeP through full-thickness skin was higher than dermis-to-epidermis Permeation. Epidermis-to-dermis Permeations of fluorescein isothiocyanate dextran (FD-4) and isosorbide 5-mononitrate with negative log K _ o/w were also higher than those in the opposite direction.ConclusionsMorphological observation of skin after FD-4 Permeation suggested that a conically shaped trans-follicular Permeation pathway model could be advocated to explain the difference between the epidermis-to-dermis Permeation and that in the opposite direction.
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effect of several electrolyzed waters on the skin Permeation of lidocaine benzoic acid and isosorbide mononitrate
Drug Development and Industrial Pharmacy, 2009Co-Authors: Toshihiko Kitamura, Hiroaki Todo, Kenji SugibayashiAbstract:The effects of several electrolyzed waters were evaluated on the Permeation of model base, acid and non-ionized compounds, lidocaine (LC), benzoic acid (BA), and isosorbide mononitrate (ISMN), respectively, through excised hairless rat skin. Strong alkaline-electrolyzed reducing water (ERW) enhanced and suppressed the skin Permeation of LC and BA, respectively, and it also increased the skin Permeation of ISMN, a non-ionized compound. On the contrary, strong acidic electrolyzed oxidizing water (EOW) enhanced BA Permeation, whereas suppressing LC Permeation. Only a marginal effect was observed on the skin Permeation of ISMN by EOW. These marked enhancing effects of ERW on the skin Permeation of LC and ISMN were explained by pH partition hypothesis as well as a decrease in skin impedance. The present results strongly support that electrolyzed waters, ERW and EOW, can be used as a new vehicle in topical pharmaceuticals or cosmetics to modify the skin Permeation of drugs without severe skin damage.
Faiyaz Shakeel - One of the best experts on this subject based on the ideXlab platform.
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Comparative topical delivery of antifungal drug croconazole using liposome and micro-emulsion-based gel formulations
Drug Delivery, 2014Co-Authors: Mahmoud El-badry, Gihan Fetih, Faiyaz ShakeelAbstract:The aim of this study was to develop liposomal-based (LBGF) and micro-emulsion-based (MBGF) gel formulations of croconazole to compare their topical delivery potential. Conventional gels were also prepared using various polymers such as sodium carboxymethyl cellulose (SCMC), Poloxamer 407, Carbopol 971P and chitosan. The in vitro release of croconazole from conventional gel formulations, LBGF and MBGF were carried out using cellophane membrane as Permeation membrane. However, in vitro skin Permeations studies of all formulations were carried out using rat skin. The results of the drug release/skin Permeation studies indicated that the highest release was obtained from SCMC followed by chitosan, Poloxamer 407 and finally Carbopol 971P gel. Therefore, liposomes and micro-emulsions were loaded on Carbopol 971P gel. The drug release and skin Permeation of croconazole from different LBGF and MBGF showed that MBGF had superior release/Permeation than LBGF. MBGF having ethanol as co-surfactant showed higher release/Permeation of drug than MBGF-containing propylene glycol. The analysis of data according to different kinetic models indicated that the release of drug from different LBGF and MBGF followed the Higuchi model. The antimicrobial activity of the different LBGF and MBGF of croconazole was carried out by measuring the inhibition zone (mm) and compared by the effect of miconazole cream as control. The different LBGF and MBGF showed an excellent activity against different species of fungi as compared with miconazole cream. Overall, these results indicated that developed LBGF and MBGF could have great potential for topical delivery of croconazole. © 2014 Informa Healthcare USA, Inc.
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formulation and evaluation of once a day transdermal gels of diclofenac diethylamine
Methods and Findings in Experimental and Clinical Pharmacology, 2006Co-Authors: Sanjula Baboota, Faiyaz Shakeel, Kanchan KohliAbstract:The present study was undertaken to prepare and evaluate transdermal gels of diclofenac diethylamine (DDEA) containing penetration enhancers such as olesan oil® and dimethyl sulfoxide (DMSO). Transdermal gels were prepared using different polymers such as carbopol-940, polyvinyl alcohol (PVA), hydroxy propyl methyl cellulose-K 4 M, hydroxy propyl cellulose-M, and sodium carboxy methyl cellulose. The formulated gels were subjected to physicochemical studies, in vitro release studies and in vitro skin Permeations studies and were evaluated for drug content, viscosity, extrudability, spreadability, and pH. The in vitro release studies of prepared gels were performed using specially designed Fites cell and in vitro skin Permeation studies were performed using keshary-chien diffusion cell through rat skin. Selected formulations were evaluated for their antiinflammatory activity using the carrageenan-induced paw edema in rats. The carbopol-940 and PVA gels containing 10% DMSO showed best in vitro skin Permeation of DDEA. In vivo study for the selected formulation showed a sustained reduction in inflammation in the carrageenan-induced paw edema in rats. The efficacies of carbopol-940 and PVA gels were also compared with that of the marketed Voveran gel,® and it was found that carbopol and PVA gels produced better results than the Voveran gel.
Bojan Zajec - One of the best experts on this subject based on the ideXlab platform.
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hydrogen Permeation barrier recognition of defective barrier film from transient Permeation rate
International Journal of Hydrogen Energy, 2011Co-Authors: Bojan ZajecAbstract:Hydrogen Permeation barrier films often exhibit lower efficiency than anticipated. The cause could be defects in the barrier film, high permeability of the defect-free (dense) barrier film, or a combination of both. It is very difficult to point at and quantify the responsible mechanism since the defects can be of submicrometer dimensions and very sparsely populated. This study addresses the recognition of the defects in the hydrogen Permeation barrier films using the hydrogen Permeation rate transient evolution analysis. For this purpose a mathematical model of the steady-state and transient hydrogen Permeation through the membrane coated either with a defective or a defect-free barrier film was developed for the diffusion limited Permeation regime. Analysis shows that a defective barrier film might be recognized only in a transient Permeation experiment. The effective diffusion coefficient of the membrane with the defect-free barrier film is variable and depends mainly on the ratio of diffusion coefficients in the film and the substrate. Contrary to this, the transient Permeation only through pinholes has a constant value of the effective diffusion coefficient. Result of the study is an experimentally useful criterion when and how the Permeation through the defects in the barrier layer can be recognized and its extent determined.
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Hydrogen Permeation barrier – Recognition of defective barrier film from transient Permeation rate
International Journal of Hydrogen Energy, 2011Co-Authors: Bojan ZajecAbstract:Hydrogen Permeation barrier films often exhibit lower efficiency than anticipated. The cause could be defects in the barrier film, high permeability of the defect-free (dense) barrier film, or a combination of both. It is very difficult to point at and quantify the responsible mechanism since the defects can be of submicrometer dimensions and very sparsely populated. This study addresses the recognition of the defects in the hydrogen Permeation barrier films using the hydrogen Permeation rate transient evolution analysis. For this purpose a mathematical model of the steady-state and transient hydrogen Permeation through the membrane coated either with a defective or a defect-free barrier film was developed for the diffusion limited Permeation regime. Analysis shows that a defective barrier film might be recognized only in a transient Permeation experiment. The effective diffusion coefficient of the membrane with the defect-free barrier film is variable and depends mainly on the ratio of diffusion coefficients in the film and the substrate. Contrary to this, the transient Permeation only through pinholes has a constant value of the effective diffusion coefficient. Result of the study is an experimentally useful criterion when and how the Permeation through the defects in the barrier layer can be recognized and its extent determined.
