What is the key to the preparation of oral liquid?

Key points: the drug should be soluble in water, and the toxicity of the added auxiliary materials should be low. Oral bioavailability should be high, stable and sterile.

Oral liquid has the advantages of small dosage, fast absorption, stable quality, convenient carrying and taking, and easy storage, and is especially suitable for industrial production. Some varieties can be used as Chinese medicine first aid, such as Sinitang oral liquid and Yinhuang oral liquid. Therefore, in recent years, tablets, granules, pills, decoction, traditional Chinese medicine mixture, injection and so on. It has been transformed into oral liquid, making it one of the rapidly developing dosage forms in pharmaceutical preparations. However, the production equipment and technological conditions of oral liquid are high and the cost is expensive.

Generally, it is prepared by decocting method (method is the same as traditional Chinese medicine mixture). First, concentrate the decoction properly, then add a certain proportion of ethanol to precipitate water-soluble impurities, or remove fat-soluble impurities by ethanol extraction and water precipitation, and then add appropriate additives (common correctants, bacteriostats, antioxidants, colorants, etc.). ), dissolving and mixing, filtering and clarifying, filling in ampoules or bottles with easy-to-open lids according to the requirements of injection technology, and sterilizing.

Liquid drugs usually need clarification. Therefore, after concentration, the extract is generally filtered by heat treatment, refrigeration and other methods to remove impurities. Due to the high concentration of liquid medicine, plate-and-frame filter press, microporous filter or hollow fiber ultrafiltration equipment are generally used for filtration to ensure clarity.