Evaluation of a direct spectrophotometric method for percutaneous bioavailability studies

The lateral spreading of topically applied substances is a competitive process to the penetration into the stratum corneum (SC). The penetration of topically applied UV filter substances into the human SC and the lateral spreading were investigated in vivo. Tape stripping in combination with spectroscopic measurements was used to study both processes of two UV filter substances. The concentration of both UV filters was determined inside and outside the application area by varying the application and tape stripping protocol. A spreading of the topically applied substances from the treated to the untreated areas was observed, which caused a concentration gradient. This lateral spreading depends on the time between application and tape stripping and the size of the treated skin area. Significant amounts of topically applied substances were found adjoining the application area, due to the lateral spreading which takes place on the skin surface. In general, the lateral spreading must be considered to be a competitive process when studying penetration processes of topically applied substances. It has to be considered during drug treatment of small limited skin areas and for the interpretation of recovery rates obtained in penetration studies.

“…The same behavior is described for other topically applied substances, as clobetasol propionate applied at different formulations [1,3] and UV filter substances [8,12,13].…”

Section: Discussionmentioning

confidence: 85%

Lateral Spreading of Topically Applied UV Filter Substances Investigated by Tape Stripping

Jacobi

Weigmann

Baumann

et al. 2003

“…This method was used to calculate the horny layer profile. It was applied to determine the local position of topically applied clobetasol propionate [10] and UV filter substances [4,7].…”

Section: Correlation Between Pseudo-absorption and Weightmentioning

confidence: 99%

“…by transepidermal water loss (TEWL) [5], and penetration studies of topically applied substances. The obtained results provide information on bioavailability and dermatopharmacokinetics [6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

UV/VIS Absorbance Allows Rapid, Accurate, and Reproducible Mass Determination of Corneocytes Removed by Tape Stripping

Weigmann¹,

Lindemann²,

Antoniou³

et al. 2003

The accurate determination of the mass of the horny layer removed by tape stripping is a decisive prerequisite for the application of this technique in penetration studies. A novel method using optical spectroscopy to determine the amount of stratum corneum (SC) is presented. We could show that the absorbance measured in the visible spectral range accurately reflects the mass of the SC fixed on individual tapes. Furthermore, absorbance measurement allows determination of the absolute mass of corneocyte aggregates on the removed tape strips. Topically applied substances do not disturb the spectroscopic measurements in contrast to the conventionally employed weight determination. Identical results were obtained when performing spectroscopic horny layer quantification independently in two separate institutions. Taken together, this new method is rapid, sensitive, reproducible, and accurate. We anticipate a wide application in penetration studies as well as in dermatopharmacokinetics.

“…Both quantities are dependent on various parameters, as on the skin properties of the volunteer [2][3][4][5][6] and the applied formulation [7,8]. The information about the substance per tape and the respective mass of corneocytes allows to conclude on the local distribution of the substances within the depth profile of the SC [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Pseudo-Absorption Method to Quantify Human Stratum corneum Removed by Tape Stripping Using Protein Absorption

Lindemann

Weigmann

Schaefer

et al. 2003

Tape stripping is a well-known method to study the barrier function of the stratum corneum (SC) and penetration processes of topically applied substances into the horny layer. The quantification of the removed corneocytes for each tape strip is the prerequisite for these studies. The pseudo-absorption of the corneocytes was proposed as a measure for the quantification of the removed corneocyte aggregates. In this study, the pseudo-absorption of the corneocytes in the visible range (430 nm) is compared with the protein absorption in the UV range (278 nm) and an absorption at 652 nm obtained after staining of the SC proteins with Trypan blue. Both the protein absorption and the absorption measured after staining correlate well with the pseudo-absorption measured at 430 nm (R² = 0.92 ± 0.04 and R² = 0.95 ± 0.04, respectively).