The influence of mechanical skin treatments (massage, ultrasound, microdermabrasion, tape stripping and microneedling) on the dermal penetration efficacy was investigated. Results show that microneedling was the most effective tool. It increased the penetration efficacy (amount of penetrated active and penetration depth) by a factor > 2. Microdermabrasion and tape stripping remove parts of the stratum corneum (SC). This reduces the barrier function and increases the penetration efficacy. Microdermabrasion removed about 23% of the SC. Tape stripping removed about 34% of the SC and thus resulted in a slightly more pronounced increase in the penetration efficacy (+31% after tape stripping and +18% after microdermabrasion). Massage and skin treatment with ultrasound decreased the penetration efficacy by about one third when compared to skin where the formulations were applied without any mechanical treatment. The penetration reducing effect is caused by mechanical stress (pressure), which reduces the thickness of the SC. The increased density of the SC is considered to decrease the intercellular space within the SC and with this the flux for chemical compounds. Therefore, massage and other mechanical treatments that increase the density of the SC should be avoided if efficient dermal penetration is required.
Keywords: Dermal penetration; Massage; Microdermabrasion; Microneedling; Skin; Tape stripping; Ultrasound.
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