TPSA is used as a molecular descriptor in drug research because it can efficiently predict a drug's ability to passively cross biological membranes, such as the intestinal lining or the blood-brain barrier . This efficiency is crucial in early drug discovery stages, where researchers need to evaluate a large number of potential drug candidates. Several studies have shown that TPSA correlates well with drug permeability . For instance, drugs that are readily absorbed from the gut or those that can penetrate the central nervous system typically have lower TPSA values . TPSA has also been used in a model that predicts drug exposure in pregnant women and their fetuses. This model relies on a "permeability-limited placenta model" that simulates drug transfer between the mother and fetus .