Propylene glycol is a colorless, odorless, hygroscopic viscous liquid characterized by lubricating, moisturizing, penetrating, and solubilizing properties. In the pharmaceutical, food, and cosmetics industries, it is used as a lubricant, humectant, and solvent. It also serves as an excipient to enhance the solubility of drugs and is widely utilized in topical, oral, or intravenous pharmaceutical products.