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Zamani Zakaria A, Jepps OG, Gould T, Anissimov YG. Permeable Cornified Envelope Layer Regulates the Solute Transport in Human Stratum Corneum. J Pharm Sci 2023; 112:1939-1946. [PMID: 36931344 DOI: 10.1016/j.xphs.2023.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 03/06/2023] [Accepted: 03/06/2023] [Indexed: 03/17/2023]
Abstract
To unravel the diffusion mechanisms of percutaneous drug delivery, suitable numerical analysis of stratum corneum structure is essential. In this research paper, we accounted for the permeable envelope layer in the brick-and-mortar finite element models of human stratum corneum. Both penetration and desorption experiments for tritiated water were simulated by transient finite element analysis. Rivet-shaped corneodesmosomes were included in the brick and mortar model. Results showed that cornified lipid permeability (Penv) is a determinant in desorption of the solute, while lipid transverse diffusion coefficient (Dlip-trans) is prominent during penetration. These two major unknowns (Penv and Dlip-trans) were obtained by extensive fitting of the finite element model to the experimental water data. Penv and Dlip-trans were determined to be 1×10-2 cm/s and 5.7×10-10 cm2/s, respectively.
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Affiliation(s)
- Afshin Zamani Zakaria
- School of Environment and Science, Griffith University, Queensland 4111, Australia; Queensland Micro and Nanotechnology Centre, Griffith University, Nathan, Queensland 4111, Australia.
| | - Owen G Jepps
- School of Environment and Science, Griffith University, Queensland 4111, Australia; Queensland Micro and Nanotechnology Centre, Griffith University, Nathan, Queensland 4111, Australia.
| | - Tim Gould
- School of Environment and Science, Griffith University, Queensland 4111, Australia; Queensland Micro and Nanotechnology Centre, Griffith University, Nathan, Queensland 4111, Australia
| | - Yuri G Anissimov
- Queensland Micro and Nanotechnology Centre, Griffith University, Nathan, Queensland 4111, Australia
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2
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Wang J, Nitsche JM, Kasting GB, Wittum G, Nägel A. Transdermal and lateral effective diffusivities for drug transport in stratum corneum from a microscopic anisotropic diffusion model. Eur J Pharm Biopharm 2023:S0939-6411(23)00032-2. [PMID: 36764498 DOI: 10.1016/j.ejpb.2023.01.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 10/10/2022] [Accepted: 01/27/2023] [Indexed: 02/11/2023]
Abstract
This paper presents a computational model of molecular diffusion through the interfollicular stratum corneum. Specifically, it extends an earlier two-dimensional microscopic model for the permeability in two ways: (1) a microporous leakage pathway through the intercellular lipid lamellae allows slow permeation of highly hydrophilic permeants through the tissue; and (2) the model yields explicit predictions of both lateral (D‾‖sc) and transdermal (D‾⊥sc) effective (average, homogenized) diffusivities of solutes within the tissue. We present here the mathematical framework for the analysis and a comparison of the predictions with experimental data on desorption of both hydrophilic and lipophilic solutes from human stratum corneum in vitro. Diffusion in the lipid lamellae is found to make the effective diffusivity highly anisotropic, with the predicted ratio D‾‖sc/D‾⊥sc ranging from 34-39 for fully hydrated skin and 150 to more than 1000 for partially hydrated skin. The diffusivities and their ratio are in accord with both experimental data and the results of mathematical analyses performed by others.
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Affiliation(s)
- Junxi Wang
- Goethe Center for Scientific Computing, Kettenhofweg 139, Goethe University, 60325 Frankfurt a.M., Germany
| | - Johannes M Nitsche
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, NY 14260-4200, USA
| | - Gerald B Kasting
- James L. Winkle College of Pharmacy, University of Cincinnati Academic Health Center, Cincinnati, OH 45267-0514, USA
| | - Gabriel Wittum
- Goethe Center for Scientific Computing, Kettenhofweg 139, Goethe University, 60325 Frankfurt a.M., Germany; King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi-Arabia
| | - Arne Nägel
- Goethe Center for Scientific Computing, Kettenhofweg 139, Goethe University, 60325 Frankfurt a.M., Germany.
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3
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Shamaprasad P, Frame CO, Moore TC, Yang A, Iacovella CR, Bouwstra JA, Bunge AL, McCabe C. Using molecular simulation to understand the skin barrier. Prog Lipid Res 2022; 88:101184. [PMID: 35988796 PMCID: PMC10116345 DOI: 10.1016/j.plipres.2022.101184] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 08/11/2022] [Accepted: 08/12/2022] [Indexed: 11/15/2022]
Abstract
Skin's effectiveness as a barrier to permeation of water and other chemicals rests almost entirely in the outermost layer of the epidermis, the stratum corneum (SC), which consists of layers of corneocytes surrounded by highly organized lipid lamellae. As the only continuous path through the SC, transdermal permeation necessarily involves diffusion through these lipid layers. The role of the SC as a protective barrier is supported by its exceptional lipid composition consisting of ceramides (CERs), cholesterol (CHOL), and free fatty acids (FFAs) and the complete absence of phospholipids, which are present in most biological membranes. Molecular simulation, which provides molecular level detail of lipid configurations that can be connected with barrier function, has become a popular tool for studying SC lipid systems. We review this ever-increasing body of literature with the goals of (1) enabling the experimental skin community to understand, interpret and use the information generated from the simulations, (2) providing simulation experts with a solid background in the chemistry of SC lipids including the composition, structure and organization, and barrier function, and (3) presenting a state of the art picture of the field of SC lipid simulations, highlighting the difficulties and best practices for studying these systems, to encourage the generation of robust reproducible studies in the future. This review describes molecular simulation methodology and then critically examines results derived from simulations using atomistic and then coarse-grained models.
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Affiliation(s)
- Parashara Shamaprasad
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America
| | - Chloe O Frame
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America
| | - Timothy C Moore
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America
| | - Alexander Yang
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America
| | - Christopher R Iacovella
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America
| | - Joke A Bouwstra
- Division of BioTherapeutics, LACDR, Leiden University, 2333 CC Leiden, the Netherlands
| | - Annette L Bunge
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO 80401, United States of America
| | - Clare McCabe
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235-1604, United States of America; Multiscale Modeling and Simulation (MuMS) Center, Vanderbilt University, Nashville, TN 37235-1604, United States of America; School of Engineering and Physical Science, Heriot-Watt University, Edinburgh, United Kingdom.
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Nitsche JM, Kasting GB. A Framework for Incorporating Transient Solute-Keratin Binding Into Dermal Absorption Models. J Pharm Sci 2022; 111:2093-2106. [DOI: 10.1016/j.xphs.2021.11.026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 11/28/2021] [Accepted: 11/29/2021] [Indexed: 12/28/2022]
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Roberts MS, Cheruvu HS, Mangion SE, Alinaghi A, Benson HA, Mohammed Y, Holmes A, van der Hoek J, Pastore M, Grice JE. Topical drug delivery: History, percutaneous absorption, and product development. Adv Drug Deliv Rev 2021; 177:113929. [PMID: 34403750 DOI: 10.1016/j.addr.2021.113929] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 08/05/2021] [Accepted: 08/11/2021] [Indexed: 02/07/2023]
Abstract
Topical products, widely used to manage skin conditions, have evolved from simple potions to sophisticated delivery systems. Their development has been facilitated by advances in percutaneous absorption and product design based on an increasingly mechanistic understanding of drug-product-skin interactions, associated experiments, and a quality-by-design framework. Topical drug delivery involves drug transport from a product on the skin to a local target site and then clearance by diffusion, metabolism, and the dermal circulation to the rest of the body and deeper tissues. Insights have been provided by Quantitative Structure Permeability Relationships (QSPR), molecular dynamics simulations, and dermal Physiologically Based PharmacoKinetics (PBPK). Currently, generic product equivalents of reference-listed products dominate the topical delivery market. There is an increasing regulatory interest in understanding topical product delivery behavior under 'in use' conditions and predicting in vivo response for population variations in skin barrier function and response using in silico and in vitro findings.
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Abstract
Biologics now constitute a significant element of available medical treatments. Owing to their clinical and commercial success, biologics are a rapidly growing class and have become a dominant therapeutic modality. Although most of the successful biologics to date are drugs that bear a peptidic backbone, ranging from small peptides to monoclonal antibodies (~500 residues; 150 kDa), new biologic modalities, such as nucleotide-based therapeutics and viral gene therapies, are rapidly maturing towards widespread clinical use. Given the rise of peptides and proteins in the pharmaceutical landscape, tremendous research and development interest exists in developing less-invasive or non-invasive routes for the systemic delivery of biologics, including subcutaneous, transdermal, oral, inhalation, nasal and buccal routes. This Review summarizes the current status, latest updates and future prospects for such delivery of peptides, proteins and other biologics.
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Li BS, Cary JH, Maibach HI. Should we instruct patients to rub topical agents into skin? The evidence. J DERMATOL TREAT 2018; 30:328-332. [PMID: 30247942 DOI: 10.1080/09546634.2018.1527997] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Background: At least 15 factors influence the ability of compounds to penetrate the skin. Massage (rubbing) may be another factor that has gone relatively unrecognized. Method: PubMed, Google Scholar, and EMBASE databases were accessed online in March 2018 in search of studies measuring absorption through skin with and without rubbing or massage. Results: While some studies noted no difference in dermal absorption with regards to rubbing, others have demonstrated the opposite. In general, massage technique does indeed sometimes enhance dermal absorption. In addition to increase skin temperature and blood flow, rubbing likely modifies stratum corneum (SC) structure to enhance diffusion rates and increase retained penetrant amount within the skin. Conclusions: Understanding the mechanism of massage and its role in percutaneous penetration may help elucidate skin barrier function, dermal absorption, skin decontamination, and dermatotoxicology. To achieve such goals, an in vitro model that models in vivo behaviors must first be established. Subsequently, experiments with different penetrants, vehicles, massage time, and other variables may be considered.
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Affiliation(s)
- Becky S Li
- a Howard University College of Medicine , Washington , DC , USA.,b Department of Dermatology, San Francisco School of Medicine , University of California San Francisco , San Francisco , CA , USA
| | - John Havens Cary
- b Department of Dermatology, San Francisco School of Medicine , University of California San Francisco , San Francisco , CA , USA.,c Louisiana State University School of Medicine , New Orleans , LA , USA
| | - Howard I Maibach
- b Department of Dermatology, San Francisco School of Medicine , University of California San Francisco , San Francisco , CA , USA
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8
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Nitsche JM, Kasting GB. How Predictable Are Human Stratum Corneum Lipid/Water Partition Coefficients? Assessment and Useful Correlations for Dermal Absorption. J Pharm Sci 2017; 107:727-738. [PMID: 28818392 DOI: 10.1016/j.xphs.2017.07.026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 07/24/2017] [Accepted: 07/31/2017] [Indexed: 10/19/2022]
Abstract
Partition coefficients between human stratum corneum lipids and water (Ksclip/w) are collected or deduced from a variety of sources in a manner that approximately doubles the available data compared to the current state-of-the-art model (Hansen et al., Adv Drug Deliv Rev. 2013;65(2):251-264). An additional datum for water itself in porcine SC that considerably extends the molecular size and lipophilicity range of the data set is considered. The data are analyzed in terms of an extended linear free energy relationship involving octanol/water partition coefficients, Abraham solvation parameters, and a secondary, power law molecular weight dependence. The optimum fit to log Ksclip/w for the full data set reduces the standard error of prediction from 0.50 for a Hansen-like model to 0.39; corresponding multiplicative errors in Ksclip/w are reduced from a factor of 3.1 to one of 2.5. The difference in performance is driven by the water datum, which requires a more complex dependence on molecular size than that afforded by Abraham parameters. In the absence of the water value, the Hansen-like model, which does not include a dependence on molecular size, is essentially optimum. A comparison is presented to fluid-phase phospholipid-water systems, which have a demonstrably different structure-property relationship.
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Affiliation(s)
- Johannes M Nitsche
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-4200.
| | - Gerald B Kasting
- James L. Winkle College of Pharmacy, University of Cincinnati Academic Health Center, Cincinnati, Ohio 45267-0514
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Zhang A, Jung EC, Zhu H, Zou Y, Hui X, Maibach H. Vehicle effects on human stratum corneum absorption and skin penetration. Toxicol Ind Health 2016; 33:416-425. [PMID: 27436841 DOI: 10.1177/0748233716656119] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This study evaluated the effects of three vehicles-ethanol (EtOH), isopropyl alcohol (IPA), and isopropyl myristate (IPM)-on stratum corneum (SC) absorption and diffusion of the [14C]-model compounds benzoic acid and butenafine hydrochloride to better understand the transport pathways of chemicals passing through and resident in SC. Following application of topical formulations to human dermatomed skin for 30 min, penetration flux was observed for 24 h post dosing, using an in vitro flow-through skin diffusion system. Skin absorption and penetration was compared to the chemical-SC (intact, delipidized, or SC lipid film) binding levels. A significant vehicle effect was observed for chemical skin penetration and SC absorption. IPA resulted in the greatest levels of intact SC/SC lipid absorption, skin penetration, and total skin absorption/penetration of benzoic acid, followed by IPM and EtOH, respectively. For intact SC absorption and total skin absorption/penetration of butenafine, the vehicle that demonstrated the highest level of sorption/penetration was EtOH, followed by IPA and IPM, respectively. The percent doses of butenafine that were absorbed in SC lipid film and penetrated through skin in 24 h were greatest for IPA, followed by EtOH and IPM, respectively. The vehicle effect was consistent between intact SC absorption and total chemical skin absorption and penetration, as well as SC lipid absorption and chemical penetration through skin, suggesting intercellular transport as a main pathway of skin penetration for model chemicals. These results suggest the potential to predict vehicle effects on skin permeability with simple SC absorption assays. As decontamination was applied 30 min after chemical exposure, significant vehicle effects on chemical SC partitioning and percutaneous penetration also suggest that skin decontamination efficiency is vehicle dependent, and an effective decontamination method should act on chemical solutes in the lipid domain.
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Affiliation(s)
- Alissa Zhang
- 1 Department of Chemical and Physical Biology, Harvard University, Cambridge, MA, USA
| | - Eui-Chang Jung
- 2 Department of Dermatology, University of California San Francisco, San Francisco, CA, USA
| | - Hanjiang Zhu
- 2 Department of Dermatology, University of California San Francisco, San Francisco, CA, USA
| | - Ying Zou
- 3 Skin & Cosmetic Research Department, Shanghai Skin Disease Hospital, Shanghai, China
| | - Xiaoying Hui
- 2 Department of Dermatology, University of California San Francisco, San Francisco, CA, USA
| | - Howard Maibach
- 2 Department of Dermatology, University of California San Francisco, San Francisco, CA, USA
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10
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Rush AK, Miller MA, Smith ED, Kasting GB. A quantitative radioluminographic imaging method for evaluating lateral diffusion rates in skin. J Control Release 2015; 216:1-8. [DOI: 10.1016/j.jconrel.2015.07.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 07/29/2015] [Accepted: 07/30/2015] [Indexed: 11/28/2022]
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11
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Zhu H, Jung EC, Hui X, Maibach H. Proposed human stratum corneum water domain in chemical absorption. J Appl Toxicol 2015. [PMID: 26206725 DOI: 10.1002/jat.3208] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Compounds with varying physical and chemical properties may have different affinities to the stratum corneum (SC) and/or its intercellular lipids, keratin protein, and possible water domains. To better understand the mechanism of percutaneous absorption, we utilized 21 carbon-14 labeled chemicals, with wide hydrophilicity (log P = -0.05 to 6.17), and quantified their absorption/adsorption properties for a short incubation time (15 min) with regards to intact SC membrane, delipidized SC membrane and SC lipid. A facile method was developed for SC/lipid absorption, providing a more equivalent procedure and comparable data. SC lipid absorption of chemical solutes positively correlated with the octanol/water partition coefficient (log P). Differences between the percent dose of chemical absorption to intact SC and the total percent dose contributed by the protein and lipid domains suggest the possibility and significance of a water domain. Absorption rate experiments showed a longer lag time for intact SC than for delipidized SC or SC lipid, suggesting that the water domain may delay chemical binding to protein and lipid domains, and may be a factor in the resistance of many chemicals to current decontamination methods. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Hanjiang Zhu
- Department of Dermatology, University of California, San Francisco, CA, 94143-0989, USA
| | - Eui-Chang Jung
- Department of Dermatology, University of California, San Francisco, CA, 94143-0989, USA
| | - Xiaoying Hui
- Department of Dermatology, University of California, San Francisco, CA, 94143-0989, USA
| | - Howard Maibach
- Department of Dermatology, University of California, San Francisco, CA, 94143-0989, USA
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12
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Selzer D, Neumann D, Schaefer UF. Mathematical models for dermal drug absorption. Expert Opin Drug Metab Toxicol 2015; 11:1567-83. [PMID: 26166490 DOI: 10.1517/17425255.2015.1063615] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
INTRODUCTION Mathematical models of dermal transport offer the advantages of being much faster and less expensive than in vitro or in vivo studies. The number of methods used to create such models has been increasing rapidly, probably due to the steady rise in computational power. Although each of the various approaches has its own virtues and limitations, it may be difficult to decide which approach is best suited to address a given problem. AREAS COVERED Here we outline the basic ideas, drawbacks and advantages of compartmental and quantitative structure-activity relationship models, as well as of analytical and numerical approaches for solving the diffusion equation. Examples of special applications of the different approaches are given. EXPERT OPINION Although some models are sophisticated and might be used in future to predict transport through damaged or diseased skin, the comparatively low availability of suitable and accurate experimental data limits extensive usage of these models and their predictive accuracy. Due to the lack of experimental data, the possibility of validating mathematical models is limited.
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Affiliation(s)
- Dominik Selzer
- a 1 Saarland University, Biopharmaceutics and Pharmaceutical Technology , 66123 Saarbruecken, Germany.,b 2 Scientific Consilience GmbH, Saarland University , Bldg. 30, 66123 Saarbruecken, Germany +49 681 302 71230 ; +49 681 302 64956 ;
| | - Dirk Neumann
- a 1 Saarland University, Biopharmaceutics and Pharmaceutical Technology , 66123 Saarbruecken, Germany.,b 2 Scientific Consilience GmbH, Saarland University , Bldg. 30, 66123 Saarbruecken, Germany +49 681 302 71230 ; +49 681 302 64956 ;
| | - Ulrich F Schaefer
- c 3 Saarland University, Biopharmaceutics and Pharmaceutical Technology , 66123 Saarbruecken, Germany
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A strategy for in-silico prediction of skin absorption in man. Eur J Pharm Biopharm 2015; 95:68-76. [PMID: 26022643 DOI: 10.1016/j.ejpb.2015.05.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 03/09/2015] [Accepted: 05/06/2015] [Indexed: 11/21/2022]
Abstract
For some time, in-silico models to address substance transport into and through the skin are gaining more and more importance in different fields of science and industry. In particular, the mathematical prediction of in-vivo skin absorption is of great interest to overcome ethical and economical issues. The presented work outlines a strategy to address this problem and in particular, investigates in-vitro and in-vivo skin penetration experiments of the model compound flufenamic acid solved in an ointment by means of a mathematical model. Experimental stratum corneum concentration-depth profiles (SC-CDP) for various time intervals using two different in-vitro systems (Franz diffusion cell, Saarbruecken penetration model) were examined and simulated with the help of a highly optimized three compartment numerical diffusion model and compared to the findings of SC-CDPs of the in-vivo scenario. Fitted model input parameters (diffusion coefficient and partition coefficient with respect to the stratum corneum) for the in-vitro infinite dose case could be used to predict the in-use conditions in-vitro. Despite apparent differences in calculated partition coefficients between in-vivo and in-vitro studies, prediction of in-vivo scenarios from input parameters calculated from the in-vitro case yielded reasonable results.
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14
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Mojumdar EH, Helder RWJ, Gooris GS, Bouwstra JA. Monounsaturated fatty acids reduce the barrier of stratum corneum lipid membranes by enhancing the formation of a hexagonal lateral packing. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:6534-43. [PMID: 24818519 DOI: 10.1021/la500972w] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The effectiveness of the skin barrier underlies the outer layer of the skin: the stratum corneum (SC). However, in several skin diseases this barrier is impaired. In two inflammatory skin diseases, atopic eczema and Netherton syndrome, an increased level of monounsaturated fatty acids (MUFAs) has been observed as opposed to healthy skin. In the present study, we aimed to investigate the effect of MUFAs on the lipid organization and skin lipid barrier using an in vitro model membrane system, the stratum corneum substitute (SCS), mimicking the SC lipid composition and organization. To achieve our goal, the SCS has been prepared with increasing levels of MUFAs using various chain length. Permeation studies and trans-epidermal water loss measurements show that an increment of MUFAs reduces the lipid barrier in the SCS. The increased level of unsaturation exerts its effect by reducing the packing density in the lipid organization, while the lamellar phases are not affected. Our findings indicate that increased levels of MUFAs may contribute to the impaired skin barrier in diseased skin.
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Affiliation(s)
- Enamul H Mojumdar
- Leiden Academic Center for Drug Research, Department of Drug Delivery Technology, Gorlaeus Laboratories, University of Leiden , 2333 CC Leiden, The Netherlands
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15
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Lorencini M, Brohem CA, Dieamant GC, Zanchin NI, Maibach HI. Active ingredients against human epidermal aging. Ageing Res Rev 2014; 15:100-15. [PMID: 24675046 DOI: 10.1016/j.arr.2014.03.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 03/10/2014] [Accepted: 03/17/2014] [Indexed: 02/07/2023]
Abstract
The decisive role of the epidermis in maintaining body homeostasis prompted studies to evaluate the changes in epidermal structure and functionality over the lifetime. This development, along with the identification of molecular mechanisms of epidermal signaling, maintenance, and differentiation, points to a need for new therapeutic alternatives to treat and prevent skin aging. In addition to recovering age- and sun-compromised functions, proper treatment of the epidermis has important esthetic implications. This study reviews active ingredients capable of counteracting symptoms of epidermal aging, organized according to the regulation of specific age-affected epidermal functions: (1) several compounds, other than retinoids and derivatives, act on the proliferation and differentiation of keratinocytes, supporting the protective barrier against mechanical and chemical insults; (2) natural lipidic compounds, as well as glycerol and urea, are described as agents for maintaining water-ion balance; (3) regulation of immunological pathogen defense can be reinforced by natural extracts and compounds, such as resveratrol; and (4) antioxidant exogenous sources enriched with flavonoids and vitamin C, for example, improve solar radiation protection and epidermal antioxidant activity. The main objective is to provide a functional classification of active ingredients as regulatory elements of epidermal homeostasis, with potential cosmetic and/or dermatological applications.
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16
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A microscopic multiphase diffusion model of viable epidermis permeability. Biophys J 2013; 104:2307-20. [PMID: 23708370 DOI: 10.1016/j.bpj.2013.03.056] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2012] [Revised: 03/25/2013] [Accepted: 03/26/2013] [Indexed: 11/21/2022] Open
Abstract
A microscopic model of passive transverse mass transport of small solutes in the viable epidermal layer of human skin is formulated on the basis of a hexagonal array of cells (i.e., keratinocytes) bounded by 4-nm-thick, anisotropic lipid bilayers and separated by 1-μm layers of extracellular fluid. Gap junctions and tight junctions with adjustable permeabilities are included to modulate the transport of solutes with low membrane permeabilities. Two keratinocyte aspect ratios are considered to represent basal and spinous cells (longer) and granular cells (more flattened). The diffusion problem is solved in a unit cell using a coordinate system conforming to the hexagonal cross section, and an efficient two-dimensional treatment is applied to describe transport in both the cell membranes and intercellular spaces, given their thinness. Results are presented in terms of an effective diffusion coefficient, D¯(epi), and partition coefficient, K¯(epi/w), for a homogenized representation of the microtransport problem. Representative calculations are carried out for three small solutes-water, L-glucose, and hydrocortisone-covering a wide range of membrane permeability. The effective transport parameters and their microscopic interpretation can be employed within the context of existing three-layer models of skin transport to provide more realistic estimates of the epidermal concentrations of topically applied solutes.
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17
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Chen L, Han L, Lian G. Recent advances in predicting skin permeability of hydrophilic solutes. Adv Drug Deliv Rev 2013; 65:295-305. [PMID: 22580335 DOI: 10.1016/j.addr.2012.05.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Revised: 05/02/2012] [Accepted: 05/02/2012] [Indexed: 11/24/2022]
Abstract
Understanding the permeation of hydrophilic molecules is of relevance to many applications including transdermal drug delivery, skin care as well as risk assessment of occupational, environmental, or consumer exposure. This paper reviews recent advances in modeling skin permeability of hydrophilic solutes, including quantitative structure-permeability relationships (QSPR) and mechanistic models. A dataset of measured human skin permeability of hydrophilic and low hydrophobic solutes has been compiled. Generally statistically derived QSPR models under-estimate skin permeability of hydrophilic solutes. On the other hand, including additional aqueous pathway is necessary for mechanistic models to improve the prediction of skin permeability of hydrophilic solutes, especially for highly hydrophilic solutes. A consensus yet has to be reached as to how the aqueous pathway should be modeled. Nevertheless it is shown that the contribution of aqueous pathway can constitute to more than 95% of the overall skin permeability. Finally, future prospects and needs in improving the prediction of skin permeability of hydrophilic solutes are discussed.
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Naegel A, Heisig M, Wittum G. Detailed modeling of skin penetration--an overview. Adv Drug Deliv Rev 2013; 65:191-207. [PMID: 23142646 DOI: 10.1016/j.addr.2012.10.009] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 06/28/2012] [Accepted: 10/17/2012] [Indexed: 11/20/2022]
Abstract
In recent years, the combination of computational modeling and experiments has become a useful tool that is proving increasingly powerful for explaining biological complexity. As computational power is increasing, scientists are able to explore ever more complex models in finer detail and to explain very complex real world data. This work provides an overview of one-, two- and three-dimensional diffusion models for penetration into mammalian skin. Besides diffusive transport this includes also binding of substances to skin proteins and metabolism. These models are based on partial differential equations that describe the spatial evolution of the transport process through the biological barrier skin. Furthermore, the work focuses on analytical and numerical techniques for this type of equations such as discretization schemes or homogenization (upscaling) techniques. Finally, the work compares different geometry models with respect to the permeability.
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Affiliation(s)
- Arne Naegel
- Frankfurt University, Goethe Center for Scientific Computing, Kettenhofweg 139, 60325 Frankfurt am Main, Germany
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Hansen S, Lehr CM, Schaefer UF. Improved input parameters for diffusion models of skin absorption. Adv Drug Deliv Rev 2013; 65:251-64. [PMID: 22626979 DOI: 10.1016/j.addr.2012.04.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Revised: 04/25/2012] [Accepted: 04/30/2012] [Indexed: 10/28/2022]
Abstract
To use a diffusion model for predicting skin absorption requires accurate estimates of input parameters on model geometry, affinity and transport characteristics. This review summarizes methods to obtain input parameters for diffusion models of skin absorption focusing on partition and diffusion coefficients. These include experimental methods, extrapolation approaches, and correlations that relate partition and diffusion coefficients to tabulated physico-chemical solute properties. Exhaustive databases on lipid-water and corneocyte protein-water partition coefficients are presented and analyzed to provide improved approximations to estimate lipid-water and corneocyte protein-water partition coefficients. The most commonly used estimates of lipid and corneocyte diffusion coefficients are also reviewed. In order to improve modeling of skin absorption in the future diffusion models should include the vertical stratum corneum heterogeneity, slow equilibration processes, the absorption from complex non-aqueous formulations, and an improved representation of dermal absorption processes. This will require input parameters for which no suitable estimates are yet available.
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Seif S, Hansen S. Measuring the stratum corneum reservoir: desorption kinetics from keratin. J Pharm Sci 2012; 101:3718-28. [PMID: 22733612 DOI: 10.1002/jps.23245] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 05/30/2012] [Accepted: 06/08/2012] [Indexed: 11/11/2022]
Abstract
High keratin binding and slow desorption kinetics are assumed to be responsible for the formation of the stratum corneum (SC) reservoir. We measured equilibrium binding coefficients (K(b)) and desorption rate constants (k(off)) with bovine hoof/horn keratin and six solutes with similar molecular weight (180-288 Da) and varying lipophilicities [expressed as octanol-water distribution coefficient, i.e., a partition coefficient corrected for pH (log K(pH))-0.13 to 3.8]. Two ionizable solutes within this set were tested at different pH values as degree of ionization and lipophilicity were expected to influence equilibrium binding and desorption kinetics. The unbound fraction at equilibrium varied between 18% and 93%. All solutes exhibited linear binding isotherms within the investigated concentration range. Equilibrium binding and the rate of desorption are both functions of solute lipophilicity [log K(b) = 1.23 + 0.32 log K(pH); log k(off) = 1/(25.75 + 8.35 K(pH) (0.34))]. Our results prove that slow desorption from keratin may be a major contributor to the SC reservoir. Also, they prove that reservoir formation is relevant for lipophilic solutes independent of drug class, thus allowing new options for topical pharmacotherapy.
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Affiliation(s)
- Salem Seif
- Biopharmaceutics and Pharmaceutical Technology, Saarland University, Saarbruecken, Germany
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Moss GP, Wilkinson SC, Sun Y. Mathematical modelling of percutaneous absorption. Curr Opin Colloid Interface Sci 2012. [DOI: 10.1016/j.cocis.2012.01.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Mathematical models of skin permeability: An overview. Int J Pharm 2011; 418:115-29. [DOI: 10.1016/j.ijpharm.2011.02.023] [Citation(s) in RCA: 244] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 02/14/2011] [Accepted: 02/16/2011] [Indexed: 11/23/2022]
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Abstract
The living epidermis and dermis are rich in antigen presenting cells (APCs). Their activation can elicit a strong humoral and cellular immune response as well as mucosal immunity. Therefore, the skin is a very attractive site for vaccination, and an intradermal application of antigen may be much more effective than a subcutaneous or intramuscular injection. However, the stratum corneum (SC) is a most effective barrier against the invasion of topically applied vaccines. Products which have reached the stage of clinical testing, avoid this problem by injecting the nano‐vaccine intradermally or by employing a barrier disrupting method and applying the vaccine to a relatively large skin area. Needle‐free vaccination is desirable from a number of aspects: ease of application, improved patient acceptance and less risk of infection among them. Nanocarriers can be designed in a way that they can overcome the SC. Also incorporation into nanocarriers protects instable antigen from degradation, improves uptake and processing by APCs, and facilitates endosomal escape and nuclear delivery of DNA vaccines. In addition, sustained release systems may build a depot in the tissue gradually releasing antigen which may avoid booster doses. Therefore, nanoformulations of vaccines for transcutaneous immunization are currently a very dynamic field of research. Among the huge variety of nanocarrier systems that are investigated hopes lie on ultra‐flexible liposomes, superfine rigid nanoparticles and nanocarriers, which are taken up by hair follicles. The potential and pitfalls associated with these three classes of carriers will be discussed.
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Affiliation(s)
- Steffi Hansen
- Department of Drug Delivery, Helmholtz-Institute for Pharmaceutical Research Saarland-HIPS, Helmholtz-Center for Infection Research-HZI, Saarbruecken, Germany.
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Frasch HF, Barbero AM, Hettick JM, Nitsche JM. Tissue Binding Affects the Kinetics of Theophylline Diffusion Through the Stratum Corneum Barrier Layer of Skin. J Pharm Sci 2011; 100:2989-95. [DOI: 10.1002/jps.22489] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Revised: 11/22/2010] [Accepted: 01/01/2011] [Indexed: 11/10/2022]
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Torin Huzil J, Sivaloganathan S, Kohandel M, Foldvari M. Drug delivery through the skin: molecular simulations of barrier lipids to design more effective noninvasive dermal and transdermal delivery systems for small molecules, biologics, and cosmetics. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2011; 3:449-462. [PMID: 21595050 DOI: 10.1002/wnan.147] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The delivery of drugs through the skin provides a convenient route of administration that is often preferable to injection because it is noninvasive and can typically be self-administered. These two factors alone result in a significant reduction of medical complications and improvement in patient compliance. Unfortunately, a significant obstacle to dermal and transdermal drug delivery alike is the resilient barrier that the epidermal layers of the skin, primarily the stratum corneum, presents for the diffusion of exogenous chemical agents. Further advancement of transdermal drug delivery requires the development of novel delivery systems that are suitable for modern, macromolecular protein and nucleotide therapeutic agents. Significant effort has already been devoted to obtain a functional understanding of the physical barrier properties imparted by the epidermis, specifically the membrane structures of the stratum corneum. However, structural observations of membrane systems are often hindered by low resolutions, making it difficult to resolve the molecular mechanisms related to interactions between lipids found within the stratum corneum. Several models describing the molecular diffusion of drug molecules through the stratum corneum have now been postulated, where chemical permeation enhancers are thought to disrupt the underlying lipid structure, resulting in enhanced permeability. Recent investigations using biphasic vesicles also suggested a possibility for novel mechanisms involving the formation of complex polymorphic lipid phases. In this review, we discuss the advantages and limitations of permeation-enhancing strategies and how computational simulations, at the atomic scale, coupled with physical observations can provide insight into the mechanisms of diffusion through the stratum corneum.
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Affiliation(s)
- J Torin Huzil
- School of Pharmacy, University of Waterloo, Waterloo, Ontario, Canada.,Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
| | - Siv Sivaloganathan
- Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
| | - Mohammad Kohandel
- Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
| | - Marianna Foldvari
- School of Pharmacy, University of Waterloo, Waterloo, Ontario, Canada
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Hansen S, Selzer D, Schaefer UF, Kasting GB. An Extended Database of Keratin Binding. J Pharm Sci 2011; 100:1712-26. [DOI: 10.1002/jps.22396] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 10/01/2010] [Accepted: 10/07/2010] [Indexed: 11/08/2022]
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Nitsche JM, Frederick Frasch H. Dynamics of diffusion with reversible binding in microscopically heterogeneous membranes: General theory and applications to dermal penetration. Chem Eng Sci 2011. [DOI: 10.1016/j.ces.2011.01.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Wang L, Chen L, Lian G, Han L. Determination of partition and binding properties of solutes to stratum corneum. Int J Pharm 2010; 398:114-22. [PMID: 20674724 DOI: 10.1016/j.ijpharm.2010.07.035] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 06/30/2010] [Accepted: 07/22/2010] [Indexed: 10/19/2022]
Abstract
The binding property of a number of relatively hydrophilic solutes to native and delipidized stratum corneum (SC) and their partition coefficients to extracted lipid have been measured by equilibration experiments to expand the current database which consisted of mostly hydrophobic solutes. Using the extended database, quantitative structure property relationships (QSPR) have been proposed for predicting the partition and binding coefficients of both hydrophobic and hydrophilic solutes to the SC protein, and lipid. Solute partition to the SC lipid is best fitted by PC(lip/w)=K(ow)(0.69) and solute binding to the SC protein is best described by PC(pro/w)=4.2K(ow)(0.31). The two QSPR models of solute partition to the SC lipid and binding to the SC protein have been further combined into a two-phase model to predict the overall partition coefficient of solutes to the stratum corneum (K(sc/w)). Our study not only extends the database of solute partition and binding properties of the SC to include hydrophilic solutes, but also demonstrates that the thermodynamic equilibrium properties of the SC partition and binding can be fitted with good accuracy by combining QSPR models with the multiphase and heterogeneous structures of the SC.
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Affiliation(s)
- Liming Wang
- China Agricultural University, Beijing 100083, China
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