8.3.2.1　Lipid-water partition coefficient of drugs

Drugs with logP（P refers to the lipid-water partition coefficient）between 0 and 5 are generally considered to have comparatively strong transdermal capacity.The transdermal ability of drugs with logP at about 2 is the strongest one.Such drugs can penetrate both the hydrophilic head layer of the lipid bilayer and the hydrophobic tail layer.(https://www.daowen.com)