182 citations
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December 2007 in “BJCP. British journal of clinical pharmacology/British journal of clinical pharmacology” Hair follicles significantly increase the speed and amount of caffeine absorbed through the skin.
82 citations
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January 1994 in “Skin Pharmacology and Physiology” Hair follicles and glands significantly increase steroid absorption in skin.
52 citations
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February 1985 in “Archives of Dermatology” Minoxidil absorbs poorly through skin, with low risk of side effects at 1-2% concentration.
37 citations
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January 1997 in “Journal of Pharmaceutical Sciences” Hairless rats absorb substances through their skin more easily than hairy rats.
25 citations
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June 1990 in “Journal of Pharmaceutical Sciences” Longer contact time increases minoxidil absorption, but doesn't affect metabolism.