Significance of the follicular pathway for dermal substance penetration quantified by laser Doppler flowmetry.

The understanding of transdermal substance penetration pathways remains an important field for the development of future topical drugs and cosmetics. Laser Doppler flowmetry is a well-established method for evaluating cutaneous perfusion. In a study on 6 healthy male volunteers, we topically applied the vasoactive substance benzyl nicotinate on two test areas with open and obturated hair follicles and measured changes in the blood flow by Doppler flowmetry. Contrary to occluded follicles, the application onto the test area with open follicles led to a statistically significant perfusion increase within the first 5 minutes, emphasizing the importance of the follicular pathway for epidermal penetration.