11490 IUPAC Gold Book - polar surface area 10.1351/goldbook.11490 11490 current initialism: PSA 1 Surface area over all polar atoms (usually oxygen and nitrogen), including any attached hydrogen atoms, of a molecule. Polar surface area is a commonly used metric (c.f. molecular descriptor) for the optimisation of cell permeability. Molecules with a PSA of greater than \(\pu{1.4 nm2}\) are usually poor at permeating cell membranes. For molecules to penetrate the blood-brain barrier, the polar surface area should normally be smaller than \(\pu{0.6 nm2}\), although values up to \(\pu{0.9 nm2}\) can be tolerated. Sometimes sulfur atoms are included in the definition. The value of PSA depends on the conformation of the molecule and also the algorithm and atomic radii used in the calculation. descriptor https://goldbook.iupac.org//terms/view/11436 topological polar surface area (TPSA) https://goldbook.iupac.org//terms/view/11526 PAC, 2016, 88, 239. 'Glossary of terms used in computational drug design, part II (IUPAC Recommendations 2015)' on page 252 (https://doi.org/10.1515/pac-2012-1204) https://goldbook.iupac.org/terms/view/11490/html https://goldbook.iupac.org/terms/view/11490/json https://goldbook.iupac.org/terms/view/11490/plain Citation: 'polar surface area' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.11490 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using. 2026-08-06T20:01:02+00:00