Editing Partition coefficient (section)

==== Pharmacokinetics ====
In the context of [[pharmacokinetics]] (how the body absorbs, metabolizes, and excretes a drug), the distribution coefficient has a strong influence on [[ADME]] properties of the drug. Hence the hydrophobicity of a compound (as measured by its distribution coefficient) is a major determinant of how [[Druglikeness|drug-like]] it is. More specifically, for a drug to be orally absorbed, it normally must first pass through [[lipid bilayer]]s in the intestinal [[epithelium]] (a process known as [[transcellular]] transport). For efficient transport, the drug must be hydrophobic enough to partition into the lipid bilayer, but not so hydrophobic, that once it is in the bilayer, it will not partition out again.<ref name="Kubinyi_1979a">{{cite journal | vauthors = Kubinyi H | title = Nonlinear dependence of biological activity on hydrophobic character: the bilinear model | journal = Il Farmaco; Edizione Scientifica | volume = 34 | issue = 3 | pages = 248–76 | date = March 1979 | pmid = 43264 }}</ref><ref name="Kubinyi_1979b">{{cite journal | vauthors = Kubinyi H | title = Lipophilicity and biological activity. Drug transport and drug distribution in model systems and in biological systems | journal = Arzneimittel-Forschung | volume = 29 | issue = 8 | pages = 1067–80 | year = 1979 | pmid = 40579 }}</ref> Likewise, hydrophobicity plays a major role in determining where drugs are distributed within the body after absorption and, as a consequence, in how rapidly they are metabolized and excreted.