Transdermal transport permeability coefficient

I AM column chromatography has also been used to predict the transdermal transport of drugs [42], The retention time, log kw (capacity factor extrapolated to 100% aqueous phase at pH 5.5, IAM column) and log Poet. were compared for the studied drugs (Tables 4.11 and 4.12). The coefficients of permeability through human skin, Kp, were not correlated with either log fcw or log Poet.. The authors had, however, pre-... 

Most structure-permeation evaluations of transdermal transport indicate the strong relationship between a chemical s permeability coefficient across the skin (Aip) and its lipophilicity. Potts and Guy analyzed a diverse database of skin penetration data, comprising 91 compounds and developed a simple relation indicating that Kp depended only on lipophilicity, as measured by the chemical s octanol-water partition coefficient (P), and molecular weight (MW) ... 

This hypothesis also explains why low-frequency ultrasound can induce transdermal transport of drugs which exhibit very low passive transport. Drugs possessing low passive permeabilities are either i) hydrophilic, which makes their partitioning into the SC bilayers difficult or ii) large in molecular size (for example, proteins), which reduces their diffusion coefficients in the SC. Low-frequency ultrasound may overcome both of these limitations by providing aqueous transport channels across the skin. Since these channels are filled with saline, hydrophilic drugs can easily partition into the SC. In addition, diffusion of... 

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