Relationship between anatomical skin site and response to halcinonide and methyl nicotinate studied by bioengineering...

Regional differences in percutaneous penetration and skin properties are well documented. However, only a few studies have investigated the relationship between substance penetration and specific skin characteristics in function of the body region. It was our aim to evaluate the physiological effect of topically applied substances in function of skin parameters determined at different body regions.

The characterization of the blanching response to a topically applied corticosteroid and the characterization of the erythema response to topically applied nicotinates were used as two indicators for the percutaneous penetration at selected body regions. Stratum corneum hydration, skin temperature, TEWL, the amount of skin surface lipids and perfusion of the superficial microcirculation were determined at the same body regions.

Significant differences in pharmacodynamic response to the corticosteroids and the nicotinates were found in function of the body region. A strong correlation was detected between the parameters characterizing the pharmacodynamic response and the particular skin properties.

The regional differences in pharmacological response to topically applied halcinonide and nicotinates may point to a body region dependent bioavailability of the vasoactive substances in the upper skin layers. The significant relationship between the parameters characterizing the physiological skin reaction and the determined skin parameters may be an indication of their involvement in the percutaneous penetration process. These regional differences in pharmacological response seem to be independent of the physicochemical properties of the topically applied substances.