page_title: Polar surface area
hierarchical_section_title: Polar surface area
caption_attribution_description: English: Paracetamol Electron Map Rendering
context_page_description: The polar surface area or topological polar surface area of a molecule is defined as the surface sum over all polar atoms or molecules, primarily oxygen and nitrogen, also including their attached hydrogen atoms.
  PSA is a commonly used medicinal chemistry metric for the optimization of a drug's ability to permeate cells. Molecules with a polar surface area of greater than 140 angstroms squared tend to be poor at permeating cell membranes. For molecules to penetrate the blood–brain barrier, a PSA less than 90 angstroms squared is usually needed.
context_section_description: The polar surface area (PSA) or topological polar surface area (TPSA) of a molecule is defined as the surface sum over all polar atoms or molecules, primarily oxygen and nitrogen, also including their attached hydrogen atoms.
  PSA is a commonly used medicinal chemistry metric for the optimization of a drug's ability to permeate cells.  Molecules with a polar surface area of greater than 140 angstroms squared tend to be poor at permeating cell membranes.  For molecules to penetrate the blood–brain barrier (and thus act on receptors in the central nervous system), a PSA less than 90 angstroms squared is usually needed.
caption: Electrical potential surface of paracetamol showing polar areas in red and blue
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