The pre-freezing process is not only to protect the main properties of the substance; but also to obtain a reasonable structure of the product after freeze-drying to facilitate the sublimation of water. Pre-freezing is a very important part of the lyophilization process, so three factors should be determined before pre-freezing: the minimum temperature of pre-freezing, the speed of pre-freezing and the time of pre-freezing. CD Formulation's pharmacy experts have extensive experience and knowledge in the process of lyophilized formulations and can help our customers to better develop their drugs.
1. The eutectic point or lowest eutectic point of a formulation is an important temperature parameter that must first be known before pre-freezing. The eutectic point can be determined by resistance measurement, thermal differential analysis, direct observation by lyophilization microscopy, and numerical equation calculation. At the same time, the eutectic point is obtained by observing the change of product properties through a window during the pre-freezing step 2. We can develop a suitable measurement method according to the characteristics of your sample.
2. Adjust the speed of pre-freezing to better control the sublimation drying process. There are two ways of slow freezing, one is to reach the freezing temperature for a longer period of time, and the other is to maintain the ice near the eutectic point (porridge ice) for a period of time before dropping the temperature. And there are three ways of quick freezing, one is the product into the freeze dryer, the machine full speed refrigeration. The second is to maintain the plate temperature around 0°C after the product enters the freeze dryer, so that the product is at a lower temperature in the liquid state, and then the machine cools at full speed. The third way is to cool the plate layer to -30 ~ -35°C first, then put the products into the machine, and then the machine cools at full speed. The first method is currently used for most products. You can choose the above freezing method according to the nature of your product.
CD Formulation has professional equipment, instruments and skilled technicians to help you in the pre-freezing process.