Variations in Physical Dimensions and Chemical Composition of Human Stratum Corneum

Anderson, Robert L.; Cassidy, Jean M.

doi:10.1111/1523-1747.ep12674117

Cited by 148 publications

(82 citation statements)

References 6 publications

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“…Knowing the tape stripped area (16 cm 2 ), the SC thickness which reflects the depth of the SC barrier may be calculated assuming a value of 1 g/cm 3 for SC density [35]. This value is also similar to that for human SC density (0.8 -1.3 g/cm 3 ) reported by Anderson and Cassidy [36]. Figure 8 shows the average 18 thickness of porcine SC removed by tape stripping.…”

Section: Bradford Protein Assaysupporting

confidence: 52%

The application of ATR-FTIR spectroscopy and multivariate data analysis to study drug crystallisation in the stratum corneum

Goh

Craig

Hadgraft

et al. 2017

European Journal of Pharmaceutics and Biopharmaceutics

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Drug permeation through the intercellular lipids, which pack around and between corneocytes, may be enhanced by increasing the thermodynamic activity of the active in a formulation. However, this may also result in unwanted drug crystallisation on and in the skin. In this work, we explore the combination of ATR-FTIR spectroscopy and multivariate data analysis to study drug crystallisation in the skin.Ex vivo permeation studies of saturated solutions of diclofenac sodium (DF Na) in two vehicles, propylene glycol (PG) and dimethyl sulphoxide (DMSO), were carried out in porcine ear skin. Tape stripping and ATR-FTIR spectroscopy were conducted simultaneously to collect spectral data as a function of skin depth. Multivariate data analysis was applied to visualise and categorise the spectral data in the region of interest (1700 -1500 cm -1 ) containing the carboxylate (COO -) asymmetric stretching vibrations of DF Na. 3Spectral data showed the redshifts of the COO -asymmetric stretching vibrations for DF Na in the solution compared with solid drug. Similar shifts were evident following application of saturated solutions of DF Na to porcine skin samples. Multivariate data analysis categorised the spectral data based on the spectral differences and drug crystallisation was found to be confined to the upper layers of the skin.This proof-of-concept study highlights the utility of ATR-FTIR spectroscopy in combination with multivariate data analysis as a simple and rapid approach in the investigation of drug deposition in the skin. The approach described here will be extended to the study of other actives for topical application to the skin. GRAPHICAL ABSTRACT KEY WORDSStratum corneum; Crystallisation; ATR-FTIR; Multivariate data analysis, Porcine skin 4

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Section: Bradford Protein Assaysupporting

confidence: 52%

The application of ATR-FTIR spectroscopy and multivariate data analysis to study drug crystallisation in the stratum corneum

Goh

Craig

Hadgraft

et al. 2017

European Journal of Pharmaceutics and Biopharmaceutics

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“…(2) x is calculated from area of strip; mass of SC on tape; and the density of the SC (~ 1g/cm 3 [17]). A reciprocal transformation of equation 2 provides a linear expression which relates 1/ TEWL x to x:…”

Section: Introductionmentioning

confidence: 99%

The determination of stratum corneum thickness An alternative approach

Russell¹,

Wiedersberg²,

Delgado‐Charro³

2008

European Journal of Pharmaceutics and Biopharmaceutics

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The individual thickness of the stratum corneum is required to normalize drug permeation profiles in dermatopharmacokinetic studies. The thickness is often estimated using tape-striping combined with transepidermal water loss measurements. A linear transformation of Fick's first law is used to relate the progressively thinner barrier with the corresponding increase in transepidermal water loss and to estimate the thickness by linear regression. However, the data from an important subset of subjects are poorly fitted to this linear model. This is typically due to the removal of loose outer layers of stratum corneum, which do not contribute significantly to barrier function. This work proposes two alternative non-linear models. All three models were used to fit data from 31 in vivo tape-striping experiments and their outcomes and goodness-of-fit compared. The results suggest that the linear model may overestimate the stratum corneum thickness and is open to subjectivity regarding the selection of data points to be fitted. The non-linear models satisfactorily fitted all the data, including all data points. No significant differences were found between the thicknesses derived from the two non-linear models. However, the analysis of the goodness-of-fit of the models to the data suggests a preference for a baseline-corrected approach.

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“…The tapes were individually weighted before and after stripping to determine the removed amount of stratum corneum. With the weights of the removed stratum corneum, assuming that the density of 1 g/cm 3 is constant within the stratum corneum (Anderson & Cassidy, 1973) and the stripped area is constant, the thickness of the removed stratum corneum layer could be determined. The drug content on the single strips was analyzed with HPLC.…”

Section: Diffusion Measurements In Stratum Corneummentioning

confidence: 99%

Confocal Raman investigation of diffusion processes in monolithic type transdermal drug delivery systems

et al. 2014

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Release from a transdermal drug delivery system (TDDS) can either be controlled by diffusion in the adhesive, by diffusion processes in the stratum corneum of the skin or a combination of both. In this study, diffusion processes in monolithic type TDDS were investigated using confocal Raman microscopy. An acrylic adhesive (Duro-Tak 180-129a), a rubber adhesive (Duro-Tak H1540) and a silicone adhesive (BIO-PSA 7-4202) were used. Skin permeation of the model drug Paeonol from these adhesives was investigated. Release studies on porcine cadaver skin were carried out. Solubility of Paeonol in the different adhesives was measured. Diffusion coefficients of the drug in the TDDSs were calculated from confocal Raman depth scans, the diffusion coefficient in the stratum corneum was calculated using tape stripping. Solubility of Paeonol in the acrylic adhesive was the highest with 30 g/L among the tested systems. Paeonol had a solubility of 6 and 9 g/L in the silicone and rubber based system. Diffusion coefficient rank order was BIO-PSA 7-42044Duro-Tak 180-129a4Duro-Tak H1540. Release on porcine cadaver skin from the silicone was the highest followed by the rubber and the acrylic adhesive. During release studies on porcine skin with Duro-Tak H1540 no concentration gradient of Paeonol could be monitored in the Raman depth profiles, whereas in the stratum corneum an apparent diffusion gradient was detectable. Solubility of a drug in the adhesive dominated the release properties, high-diffusion coefficients of drugs in adhesives do not necessarily lead to high release rates from adhesives.

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Variations in Physical Dimensions and Chemical Composition of Human Stratum Corneum

Cited by 148 publications

References 6 publications

The application of ATR-FTIR spectroscopy and multivariate data analysis to study drug crystallisation in the stratum corneum

The application of ATR-FTIR spectroscopy and multivariate data analysis to study drug crystallisation in the stratum corneum

The determination of stratum corneum thickness An alternative approach

Confocal Raman investigation of diffusion processes in monolithic type transdermal drug delivery systems

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