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bibliography * The PainScience Bibliography contains plain language summaries of thousands of scientific papers and others sources, like a specialized blog. This page is about a single scientific paper in the bibliography, Park 2008.

The effect of heat on skin permeability

updated
Park JH, Lee JW, Kim YC, Prausnitz MR. The effect of heat on skin permeability. Int J Pharm. 2008 Jul;359(1-2):94–103. PubMed #18455889.
Tags: random, Epsom, toxins, controversy, debunkery, water

PainSci summary of Park 2008?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided at the bottom of the page, as often as possible. ★★★★☆?4-star ratings are for bigger/better studies and reviews published in more prestigious journals, with only quibbles. Ratings are a highly subjective opinion, and subject to revision at any time. If you think this paper has been incorrectly rated, please let me know.

This study showed that heating of the skin can dramatically increase it’s permeability. They tested primarily short bursts of intense heating: 5 milliseconds to 5 seconds, and 100 to 315 degrees Celcius. The more heat, the more molecules could cross; the duration of exposure had less effect. Skin permeability was increased by a few multiples in the low end of the range, all the way up to three orders of magnitude at the most extreme temperatures, which basically burns micropscopic holes in the surface of the skin, effectively creating artificial, temporary pores. (That sounds awful, but it’s actually painless, because the application of heat is so brief.) At lower temperatures, the increased permeability is due to disordering and disrupting the stratum corneum lipid and keratin structures, making them a less effective barrier.

~ Paul Ingraham

original abstract

Although the effects of long exposure >1s) to moderate temperatures (< or =100 degrees C) have been well characterized, recent studies suggest that shorter exposure (<1s) to higher temperatures >100 degrees C) can dramatically increase skin permeability. Previous studies suggest that by keeping exposures short, thermal damage can be localized to the stratum corneum without damaging deeper tissue. Initial clinical trials have progressed to Phase II (see http://clinicaltrials.gov), which indicates the procedure can be safe. Because the effect of heating under these conditions has received little systematic or mechanistic study, we heated full-thickness skin, epidermis and stratum corneum samples from human and porcine cadavers to temperatures ranging from 100 to 315 degrees C for times ranging from 100ms to 5s. Tissue samples were analyzed using skin permeability measurements, differential scanning calorimetry, thermomechanical analysis, thermal gravimetric analysis, brightfield and confocal microscopy, and histology. Skin permeability was shown to be a very strong function of temperature and a less strong function of the duration of heating. At optimal conditions used in this study, transdermal delivery of calcein was increased up to 760-fold by rapidly heating the skin at high temperature. More specifically, skin permeability was increased (I) by a few fold after heating to approximately 100-150 degrees C, (II) by one to two orders of magnitude after heating to approximately 150-250 degrees C and (III) by three orders of magnitude after heating above 300 degrees C. These permeability changes were attributed to (I) disordering of stratum corneum lipid structure, (II) disruption of stratum corneum keratin network structure and (III) decomposition and vaporization of keratin to create micron-scale holes in the stratum corneum, respectively. We conclude that heating the skin with short, high temperature pulses can increase skin permeability by orders of magnitude due to structural disruption and removal of stratum corneum.

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This page is part of the PainScience BIBLIOGRAPHY, which contains plain language summaries of thousands of scientific papers & others sources. It’s like a highly specialized blog.