LogP

LogP represents the partition coefficient of a compound between octanol and water, serving as a key indicator of lipophilicity and molecular distribution behaviour. It provides insight into how readily a molecule may cross biological membranes, dissolve in lipid environments, or remain in aqueous systems. LogP strongly influences drug absorption, permeability, tissue distribution, and metabolic stability, making it a central physicochemical parameter in early drug design.

The pharmaceutical industry uses LogP during lead optimisation to balance solubility and permeability, as excessive lipophilicity may reduce aqueous solubility and increase off-target binding or toxicity risks. Conversely, very low LogP can limit membrane permeability and reduce oral bioavailability. Medicinal chemists adjust LogP through structural modifications such as introducing polar groups, reducing aromaticity, or modifying ionisation properties. Regulatory expectations indirectly reflect LogP through formulation feasibility and bioavailability outcomes. As drug discovery increasingly focuses on complex targets, LogP remains a foundational metric supporting rational design of molecules that can achieve both biological potency and practical deliverability.