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Xu L, Kasting GB. Solvent and Crystallization Effects on the Dermal Absorption of Hydrophilic and Lipophilic Compounds. J Pharm Sci 2024; 113:948-960. [PMID: 37797884 DOI: 10.1016/j.xphs.2023.09.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 09/27/2023] [Accepted: 09/28/2023] [Indexed: 10/07/2023]
Abstract
This study probes the mechanisms by which volatile solvents (water, ethanol) and a nonionic surfactant (Triton X-100) influence the skin permeation of dissolved solutes following deposition of small doses onto unoccluded human skin. A secondary objective was to sharpen guidelines for the use of these and other simple solvent systems for dermal safety testing of cosmetic ingredients at finite doses. Four solutes were studied - niacinamide, caffeine, testosterone and geraniol - at doses close to that estimated to saturate the upper layers of the stratum corneum. Methods included tensiometry, visualization of spreading on skin, polarized light microscopy and in vitro permeation testing using radiolabeled solutes. Ethanol, aqueous ethanol and dilute aqueous Triton solutions all yielded surface tensions below 36 mN/m, allowing them to spread easily on the skin, unlike water (72.4 mN/m) which did not spread. Deposition onto skin of niacinamide (32 μg·cm-2) or caffeine (3.2 μg·cm-2) from water and ethanol led to crystalline deposits on the skin surface, whereas the same amounts applied from aqueous ethanol and 2 % Triton did not. Skin permeation of these compounds was inversely correlated to the extent of crystallization. A separate study with caffeine showed the absence of a dose-related skin permeability increase with Triton. Permeation of testosterone (8.2 μg·cm-2) was modestly increased when dosed from aqueous ethanol versus ethanol. Permeation of geraniol (2.9 μg·cm-2) followed the order aqueous ethanol > water ∼ 2 % Triton >> ethanol and was inversely correlated with evaporative loss. We conclude that, under the conditions tested, aqueous ethanol and Triton serve primarily as deposition aids and do not substantially disrupt stratum corneum lipids. Implications for the design of in vitro skin permeability tests are discussed.
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Affiliation(s)
- Lijing Xu
- James L. Winkle College of Pharmacy, The University of Cincinnati, Cincinnati, OH 45267-0514, USA
| | - Gerald B Kasting
- James L. Winkle College of Pharmacy, The University of Cincinnati, Cincinnati, OH 45267-0514, USA.
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2
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Tonnis K, Jaworska J, Kasting GB. Modeling the percutaneous absorption of solvent-deposited solids over a wide dose range: II. Weak electrolytes. J Control Release 2024; 365:435-447. [PMID: 37996054 DOI: 10.1016/j.jconrel.2023.11.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/13/2023] [Accepted: 11/19/2023] [Indexed: 11/25/2023]
Abstract
Dermal absorption of weak electrolytes applied to skin from pharmaceutical and cosmetic compositions is an important consideration for both their efficacy and skin safety. We developed a mechanistic, physics-based framework that simulates this process for leave on applications following solvent deposition. We incorporated this framework into our finite dose computational skin permeation model previously tested with nonelectrolytes to generate quantitative predictions for weak electrolytes. To test the model, we analyzed experimental data from an in vitro human skin permeation study of a weak acid (benzoic acid) and a weak base (propranolol) and their sodium and hydrochloride salts from simple, ethanol/water vehicles as a function of dose and ionization state. Key factors controlling absorption are the pH and buffer capacity of the dose solution, the dissolution rate of precipitated solids into a lipid boundary layer and the rate of conversion of the deposited solid to its conjugate form as the nonionized component permeates and (sometimes) evaporates from the skin surface. The resulting framework not only describes the current test data but has the potential to predict the absorption of other weak electrolytes following topical application.
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Affiliation(s)
- Kevin Tonnis
- College of Engineering and Applied Science, The University of Cincinnati, Cincinnati, OH 45221, USA
| | - Joanna Jaworska
- The Procter & Gamble Company, Data and Modeling Sciences, Brussels Innovation Center, Belgium
| | - Gerald B Kasting
- The James L. Winkle College of Pharmacy, The University of Cincinnati, Cincinnati, OH 45267-0514, USA.
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3
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Williams FM. New approaches build upon historical studies in dermal toxicology. Toxicol Res (Camb) 2023; 12:1007-1013. [PMID: 38145096 PMCID: PMC10734571 DOI: 10.1093/toxres/tfad101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 08/31/2023] [Accepted: 10/12/2023] [Indexed: 12/26/2023] Open
Abstract
These are my personal reflections on the history of approaches to understanding dermal toxicology brought together for the Paton Prize Award. This is not a comprehensive account of all publications from in vivo studies in humans to development of in vitro and in silico approaches but highlghts important progress. I will consider what is needed now to influence approaches to understanding dermal exposure with the current development and use of NAMs (new approach methodologies).
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Affiliation(s)
- Faith M Williams
- Translational and Clinical Research Institute, Medical School, Newcastle University, Newcastle NE24HH, United Kingdom
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4
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Zhang S, Cheng Z, Yang M, Guo Z, Zhao L, Baqar M, Lu Y, Wang L, Sun H. Percutaneous Penetration of Liquid Crystal Monomers (LCMs) by In Vitro Three-Dimensional Human Skin Equivalents: Possible Mechanisms and Implications for Human Dermal Exposure Risks. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:4454-4463. [PMID: 36867107 DOI: 10.1021/acs.est.2c07844] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Liquid crystal monomers (LCMs) are indispensable materials in liquid crystal displays, which have been recognized as emerging persistent, bioaccumulative, and toxic organic pollutants. Occupational and nonoccupational exposure risk assessment suggested that dermal exposure is the primary exposure route for LCMs. However, the bioavailability and possible mechanisms of dermal exposure to LCMs via skin absorption and penetration remain unclear. Herein, we used EpiKutis 3D-Human Skin Equivalents (3D-HSE) to quantitatively assess the percutaneous penetration of nine LCMs, which were detected in e-waste dismantling workers' hand wipes with high detection frequencies. LCMs with higher log Kow and greater molecular weight (MW) were more difficult to penetrate through the skin. Molecular docking results showed that ABCG2 (an efflux transporter) may be responsible for percutaneous penetration of LCMs. These results suggest that passive diffusion and active efflux transport may be involved in the penetration of LCMs across the skin barrier. Furthermore, the occupational dermal exposure risks evaluated based on the dermal absorption factor suggested the underestimation of the continuous LCMs' health risks via dermal previously.
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Affiliation(s)
- Shaohan Zhang
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Zhipeng Cheng
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Ming Yang
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Zijin Guo
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Leicheng Zhao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Mujtaba Baqar
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Yuan Lu
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Lei Wang
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Hongwen Sun
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
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5
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Miller MA, Kasting GB. Absorption of solvent-deposited weak electrolytes and their salts through human skin in vitro. Int J Pharm 2022; 620:121753. [DOI: 10.1016/j.ijpharm.2022.121753] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 04/11/2022] [Accepted: 04/13/2022] [Indexed: 11/29/2022]
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Champmartin C, Chedik L, Marquet F, Cosnier F. Occupational exposure assessment with solid substances: choosing a vehicle for in vitro percutaneous absorption experiments. Crit Rev Toxicol 2022; 52:294-316. [PMID: 36125048 DOI: 10.1080/10408444.2022.2097052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Percutaneous occupational exposure to industrial toxicants can be assessed in vitro on excised human or animal skins. Numerous factors can significantly influence skin permeation of chemicals and the flux determination. Among them, the vehicle used to solubilize the solid substances is a tricky key step. A "realistic surrogate" that closely matches the exposure scenario is recommended in first intention. When direct transposition of occupational exposure conditions to in vitro experiments is impossible, it is recommended that the vehicle used does not affect the skin barrier (in particular in terms of structural integrity, composition, or enzymatic activity). Indeed, any such effect could alter the percutaneous absorption of substances in a number of ways, as we will see. Potential effects are described for five monophasic vehicles, including the three most frequently used: water, ethanol, acetone; and two that are more rarely used, but are realistic: artificial sebum and artificial sweat. Finally, we discuss a number of criteria to be verified and the associated tests that should be performed when choosing the most appropriate vehicle, keeping in mind that, in the context of occupational exposure, the scientific quality of the percutaneous absorption data provided, and how they are interpreted, may have long-range consequences. From the narrative review presented, we also identify and discuss important factors to consider in future updates of the OECD guidelines for in vitro skin absorption experiments.
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Affiliation(s)
- Catherine Champmartin
- French National Research and Safety Institute for the Prevention of Occupational Accidents and Diseases (INRS), Vandoeuvre-les-Nancy Cedex, France
| | - Lisa Chedik
- French National Research and Safety Institute for the Prevention of Occupational Accidents and Diseases (INRS), Vandoeuvre-les-Nancy Cedex, France
| | - Fabrice Marquet
- French National Research and Safety Institute for the Prevention of Occupational Accidents and Diseases (INRS), Vandoeuvre-les-Nancy Cedex, France
| | - Frédéric Cosnier
- French National Research and Safety Institute for the Prevention of Occupational Accidents and Diseases (INRS), Vandoeuvre-les-Nancy Cedex, France
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Filetti V, Di Mizio G, Rendine M, Fortarezza P, Ricci P, Pomara C, Messina G, Riezzo I, Zammit C, Messina A, Salerno M, Sessa F. Volatile organic compounds: instrumental and canine detections link an individual to the crime scene. EGYPTIAN JOURNAL OF FORENSIC SCIENCES 2019. [DOI: 10.1186/s41935-019-0139-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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8
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Skin Permeation of Urea Under Finite Dose Condition. J Pharm Sci 2019; 108:987-995. [DOI: 10.1016/j.xphs.2018.10.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 10/03/2018] [Accepted: 10/10/2018] [Indexed: 11/19/2022]
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Frasch HF, Barbero AM. In vitro human skin permeation of benzene in gasoline: Effects of concentration, multiple dosing and skin preparation. JOURNAL OF EXPOSURE SCIENCE & ENVIRONMENTAL EPIDEMIOLOGY 2018; 28:193-201. [PMID: 28792002 PMCID: PMC6531855 DOI: 10.1038/jes.2017.10] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 05/12/2017] [Indexed: 05/03/2023]
Abstract
In vitro human skin benzene permeation was measured from gasoline formulations with benzene concentrations ranging from 0.8 to 10 vol% and from neat benzene. Steady-state fluxes (JSS), permeability coefficients (kp) and lag times (tlag) were calculated from infinite dose exposures. Permeation of benzene from small gasoline doses administered over a two-day period was also studied. The thermodynamic activity of benzene in gasoline at 30 °C was determined and the solution is near-ideal over the range from 0.8 to 100 vol%. JSS through human epidermal membranes were linear (R2=0.92) with concentration over the range from 0.8 to 10 vol%. JSS (μg/cm2/h) from gasoline (0.8 vol% benzene=6.99 mg/ml) through epidermis and full-thickness skin were 9.37±1.41 and 1.82±0.44, respectively. Neat benzene JSS was 566±138. Less than 0.25% of the total applied benzene mass from finite doses (10 μl/cm2) of gasoline was detected in receptor cells, and a small reduction of barrier function was observed from six total doses administered over 2 days. Application of these results to dermal exposure assessment examples demonstrates a range of systemic benzene uptakes that can be expected from occupational and consumer dermal exposures to gasoline, depending on the type and extent of exposure.
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Affiliation(s)
- H Frederick Frasch
- Health Effects Laboratory, National Institute for Occupational Safety and Health, Morgantown, West Virginia, USA
| | - Ana M Barbero
- Health Effects Laboratory, National Institute for Occupational Safety and Health, Morgantown, West Virginia, USA
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Intarakumhaeng R, Wanasathop A, Li SK. Effects of solvents on skin absorption of nonvolatile lipophilic and polar solutes under finite dose conditions. Int J Pharm 2018; 536:405-413. [DOI: 10.1016/j.ijpharm.2017.11.042] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 09/07/2017] [Accepted: 11/19/2017] [Indexed: 12/01/2022]
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11
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McNally K, Sams C, Loizou GD, Jones K. Evidence for non-linear metabolism at low benzene exposures? A reanalysis of data. Chem Biol Interact 2017; 278:256-268. [PMID: 28899792 DOI: 10.1016/j.cbi.2017.09.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 08/30/2017] [Accepted: 09/01/2017] [Indexed: 12/17/2022]
Abstract
The presence of a high-affinity metabolic pathway for low level benzene exposures of less than one part per million (ppm) has been proposed although a pathway has not been identified. The variation of metabolite molar fractions with increasing air benzene concentrations was suggested as evidence of significantly more efficient benzene metabolism at concentrations <0.1 ppm The evidence for this pathway is predicated on a rich data set from a study of Chinese shoe workers exposed to a wide range of benzene concentrations (not just "low level"). In this work we undertake a further independent re-analysis of this data with a focus on the evidence for an increase in the rate of metabolism of benzene exposures of less than 1 ppm. The analysis dataset consisted of measurements of benzene and toluene from personal air samplers, and measurements of unmetabolised benzene and toluene and five metabolites (phenol hydroquinone, catechol, trans, trans-muconic acid and s-phenylmercapturic acid) from post-shift urine samples for 213 workers with an occupational exposure to benzene (and toluene) and 139 controls. Measurements from control subjects were used to estimate metabolite concentrations resulting from non-occupational sources, including environmental sources of benzene. Data from occupationally exposed subjects were used to estimate metabolite concentrations as a function of benzene exposure. Correction for background (environmental exposure) sources of metabolites was achieved through a comparison of geometric means in occupationally exposed and control populations. The molar fractions of the five metabolites as a function of benzene exposure were computed. A supra-linear relationship between metabolite concentrations and benzene exposure was observed over the range 0.1-10 ppm benzene, however over the range benzene exposures of between 0.1 and 1 ppm only a modest departure from linearity was observed. The molar fractions estimated in this work were near constant over the range 0.1-10 ppm. No evidence of high affinity metabolism at these low level exposures was observed. Our reanalysis brings in to question the appropriateness of the dataset for commenting on low dose exposures and the use of a purely statistical approach to the analysis.
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Affiliation(s)
- K McNally
- Health & Safety Laboratory, Harpur Hill, Buxton, SK17 9JN, UK
| | - C Sams
- Health & Safety Laboratory, Harpur Hill, Buxton, SK17 9JN, UK
| | - G D Loizou
- Health & Safety Laboratory, Harpur Hill, Buxton, SK17 9JN, UK
| | - K Jones
- Health & Safety Laboratory, Harpur Hill, Buxton, SK17 9JN, UK.
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12
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What happens in the skin? Integrating skin permeation kinetics into studies of developmental and reproductive toxicity following topical exposure. Reprod Toxicol 2015; 58:252-81. [DOI: 10.1016/j.reprotox.2015.10.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 08/31/2015] [Accepted: 10/07/2015] [Indexed: 02/07/2023]
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13
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Safety assessment for ethanol-based topical antiseptic use by health care workers: Evaluation of developmental toxicity potential. Regul Toxicol Pharmacol 2015. [PMID: 26212636 DOI: 10.1016/j.yrtph.2015.07.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Ethanol-based topical antiseptic hand rubs, commonly referred to as alcohol-based hand sanitizers (ABHS), are routinely used as the standard of care to reduce the presence of viable bacteria on the skin and are an important element of infection control procedures in the healthcare industry. There are no reported indications of safety concerns associated with the use of these products in the workplace. However, the prevalence of such alcohol-based products in healthcare facilities and safety questions raised by the U.S. FDA led us to assess the potential for developmental toxicity under relevant product-use scenarios. Estimates from a physiologically based pharmacokinetic modeling approach suggest that occupational use of alcohol-based topical antiseptics in the healthcare industry can generate low, detectable concentrations of ethanol in blood. This unintended systemic dose probably reflects contributions from both dermal absorption and inhalation of volatilized product. The resulting internal dose is low, even under hypothetical, worst case intensive use assumptions. A significant margin of exposure (MOE) exists compared to demonstrated effect levels for developmental toxicity under worst case use scenarios, and the MOE is even more significant for typical anticipated occupational use patterns. The estimated internal doses of ethanol from topical application of alcohol-based hand sanitizers are also in the range of those associated with consumption of non-alcoholic beverages (i.e., non-alcoholic beer, flavored water, and orange juice), which are considered safe for consumers. Additionally, the estimated internal doses associated with expected exposure scenarios are below or in the range of the expected internal doses associated with the current occupational exposure limit for ethanol set by the Occupational Safety and Health Administration. These results support the conclusion that there is no significant risk of developmental or reproductive toxicity from repeated occupational exposures and high frequency use of ABHSs or surgical scrubs. Overall, the data support the conclusion that alcohol-based hand sanitizer products are safe for their intended use in hand hygiene as a critical infection prevention strategy in healthcare settings.
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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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