TLDR The new "differential stripping" method effectively measures how much substance gets into hair follicles.
The study aimed to develop a non-invasive method to quantify the amount of topically applied substances that penetrate into hair follicles. The researchers created a new technique called "differential stripping," which combines tape stripping and cyanoacrylate skin surface biopsy. This method was used to measure the penetration of a fluorescent dye into the follicles both in vitro and in vivo. They found that after 30 minutes, 5% of the applied sodium fluorescein had penetrated into the follicular infundibula, and it remained detectable after 48 hours. The study concluded that differential stripping is an effective method for selectively studying substance penetration into hair follicles.
316 citations
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June 2004 in “The journal of investigative dermatology/Journal of investigative dermatology” Microspheres about 1.5 micrometers in size can best penetrate hair follicles, potentially reaching important stem cells.
405 citations
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January 2004 in “Journal of Investigative Dermatology” Hair follicle size and distribution vary significantly across different body sites.
54 citations
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October 2002 in “Journal of controlled release” Medium lipophilic substances penetrate skin best, and adding ethanol can increase delivery to hair follicles.
69 citations
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January 2002 in “Journal of biomedical optics” Dyes can penetrate human skin and hair follicles up to 1.2 mm deep and the sebaceous gland can store dye; Indocyanine Green lotion was made for safe dyeing and monitoring.
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January 2002 in “Journal of drug targeting” Drugs penetrate scalp skin better than abdominal skin, with scalp hair follicles aiding in higher drug delivery.
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November 2012 in “Pharmaceutical research” Surface-modified nanoparticles mainly use non-follicular pathways to enhance skin permeation of ibuprofen and could improve treatment for inflammatory skin diseases.
122 citations
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April 2011 in “European Journal of Pharmaceutics and Biopharmaceutics” Particles around 100 nm can penetrate and stay in hair follicles without passing through healthy skin, making them safe for use in topical products and useful for targeted drug delivery.
59 citations
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October 2012 in “Pharmaceutical Research” Squalene-based carriers improve delivery of a treatment to hair follicles for alopecia areata.
13 citations
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October 2012 in “InTech eBooks” Nanocarriers could improve how drugs are delivered through the skin but require more research to overcome challenges and ensure safety.
211 citations
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February 2009 in “European journal of pharmaceutics and biopharmaceutics” Hair follicles help absorb and store topical compounds, aiding targeted drug delivery.
