Phthalyl-DL-glutamic acid is primarily used in the pharmaceutical industry as an intermediate in the synthesis of various drugs. It plays a crucial role in the production of certain antibiotics and anti-inflammatory medications, where it acts as a building block for more complex molecules. Additionally, it is utilized in research and development for creating novel therapeutic compounds, particularly in the field of targeted drug delivery systems. Its chemical properties make it suitable for modifying drug solubility and stability, enhancing the efficacy of pharmaceutical formulations.