Freeze-dried powder is a sterile powder injection produced by freezing a liquid drug into a solid state under sterile conditions, then sublimating the water under vacuum. The freeze-drying process involves pre-freezing the water content of the liquid drug using a vacuum freeze dryer, followed by sublimation of the frozen water under sterile conditions.
Freeze-drying is an effective method for drying heat-sensitive products and substances requiring the preservation of biological activity. This method involves freezing the water content of the product at low temperatures, then drying it under vacuum, allowing the water to sublimate directly from a solid state to water vapor and be removed from the product, thus achieving active drying.
This method effectively prevents changes in the physicochemical and biological properties of the product, minimizing damage to biological tissues and cell structures and characteristics, and rapidly inducing a dormant state. It effectively protects the stability of the active ingredients in many heat-sensitive pharmaceutical and biological products. For example, proteins and microorganisms do not undergo denaturation or lose their biological activity. Furthermore, freeze-dried products have a loose morphology and minimal color change after drying, and they dissolve rapidly in water, restoring the original physicochemical properties and biological activity of the aqueous solution. Third, because drying is carried out under vacuum conditions, it provides excellent protection for some easily oxidized substances. Fourth, the product has a very low moisture content after freeze-drying, which improves its stability and reduces the chance of contamination. This not only facilitates transportation but also extends the product's shelf life.
