162 citations
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August 2005 in “The journal of investigative dermatology/Journal of investigative dermatology” The new "differential stripping" method effectively measures how much substance gets into hair follicles.
74 citations
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June 2010 in “European Journal of Pharmaceutics and Biopharmaceutics” Minoxidil foam enters hair follicles and skin for hair growth.
26 citations
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December 2009 in “Laser Physics” Caffeine from shampoo penetrates hair follicles quickly and stays for at least 24 hours.
24 citations
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February 2007 in “Laser Physics Letters” Caffeine shampoo penetrates hair follicles deeply and stays for up to 48 hours.
15 citations
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October 2020 in “European journal of pharmaceutics and biopharmaceutics” Caffeine penetrates skin quickly through open hair follicles, but less through closed ones, with levels becoming equal after 22 hours.