partition coefficient

This term is a specialized technical expression used primarily in chemistry, pharmacology, and biochemistry. It describes how a chemical substance distributes itself between two different solvents that do not mix, such as oil and water. A high value typically indicates that a substance is lipophilic (fat-soluble), while a low value suggests it is hydrophilic (water-soluble).

In pharmaceutical research, this coefficient is critical for predicting how a drug will cross biological membranes, such as the blood-brain barrier. Because it is a ratio of concentrations, it is often expressed as a logarithm (log P) to make the resulting numbers more manageable for mathematical modeling and comparison.