The method of preparation is usually decocted (method with traditional Chinese medicine mixture). First, the decoction is concentrated into a certain proportion of ethanol to precipitate water soluble impurities, or to remove the fat soluble impurities by alcohol extraction and water precipitation, and then add suitable additive (commonly used as flavoring agent, bacteriostat, antioxidant, colorant, etc.), dissolved and mixed, filtrated and clarified, and sealed in ampoules according to the requirements of the injection process. In easy to cover bottle, sterilization is obtained.
The solution generally requires clarification. Therefore, after the extract is concentrated, it is usually treated by heat treatment and cold storage to remove impurities. Because the concentration of the solution is large, it is usually filtered by plate and frame filter press, microporous filter or hollow fiber ultrafiltration equipment to ensure clarity.