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<b>Spatial distribution of cutaneous microvasculature and local drug<br> clearance after drug application on the skin </b> <p>Gregor Cevc, Ulrich Vierl</p> <p><b>Journal of Controlled Release 118 (2007) 18–26</b></p> <p>Abstract: </p> <p>We analysed quantitatively blood microvessels distribution in normal skin. We conclude that the segmental area of blood vessels peaks approximately 0.1 mm below the skin surface, where the upper cutaneous blood plexus resides. Total blood vessels area then decreases quasi-exponentially to a depth of approx. –0.75 mm, with a decay length of ~0.1 mm, which is site and skin condition dependent, but at greater depths the decrease is approx. 6-times less steep. The corresponding permeability sink exhibits a similar, but superficially steeper, depth-profile. The lateral localisation of superficial blood vessels is such that ensures maximum diffusion from and into the capillaries, which affects transdermal drug delivery: each hairpin-like loop is in the centre of a papilla that corresponds to a cluster of corneocytes surrounded by main diffusion pathways. The aggregate area of blood vessels in the skin is ³2.5-fold greater than total organ surface area under normal physiological conditions. The molecules diffusing through the skin barrier are thus largely cleared in outermost 20% of the organ, which may create a drug concentration maximum in the dermis, if clearance increases significantly with time. Skin microdialysis data are therefore extremely sensitive to cutaneous blood flow (distribution) and sampling. Skin microvasculature and its distribution must consequently be considered in all topical or transdermal drug transport studies, for example, by including suitably formulated clearance term into generalised diffusion equation. <br> </p> <p><a href="index.html"><----</a> | <a href="../.././index.html" target="_top" onmouseover="putstattext('What is special about IDEA?'); return true;">Home</a> | <a href="../../about-us/index.html" target="_top" onmouseover="putstattext('About IDEA history, people, external collaboratory and future plans.'); return true;">About us</a> | <a href="../../corporate_factsheet/index.html" target="_top" onmouseover="putstattext('Corporate Factsheet'); return true;">Corporate Factsheet</a> | <a href="../../science/index.html" target="_top" onmouseover="putstattext('Academic collaborations, publications, etc.'); return true;">Science</a> | Publications | <a href="../../product_opportunities/index.html" target="_top" onmouseover="putstattext('IDEA offers better compliance, local drug targeting and patent protection.'); return true;">Product opportunities</a> | <a href="../../financial/index.html" target="_top" onmouseover="putstattext('Investors and basic financial data.'); return true;">Finance</a> | <a href="../../press_releases/index.html" target="_top" onmouseover="putstattext('Original texts.'); return true;">Press releases</a> | <a href="../../latest_newsletter/index.html" target="_top" onmouseover="putstattext('IDEAS latest newsletter'); return true;">Latest newsletter</a> | <a href="../../press_clippings/index.html" target="_top" onmouseover="putstattext('IDEA in the press.'); return true;">Press clippings</a> | <a href="../../conferences/index.html" target="_top" onmouseover="putstattext('Here you will find many dates where you can meet us and where we can talk...'); return true;">Conferences</a> | <a href="../../career/index.html" target="_top" onmouseover="putstattext('We constantly seek best talents and dedication, offering much in return.'); return true;">Career</a> | <a href="../../contact/index.html" target="_top" onmouseover="putstattext('We would like to hear from you!'); return true;">Contact</a> | <a href="../../faq/index.html" target="_top" onmouseover="putstattext('Product bio/acceptability, liposome/Transfersome, ...'); return true;">Scientific FAQ</a> | <a href="../../glossary/index.html" target="_top" onmouseover="putstattext(''); return true;">Glossary</a> | <a href="../../sitemap/index.html" target="_top" onmouseover="putstattext('Get an impression on IDEA!'); return true;">Site Map</a> | <a href="../../search/index.html" target="_top" onmouseover="putstattext('Find documents based on keywords!'); return true;">Search</a> |  </p>