Ambroxol Hydrochloride is an active metabolite of expectorant bromohexine (n-demethylated, cyclohexyl parapposite to introduce trans hydroxyl), with lower toxicity than bromohexine, but higher activity than bromohexine. Ambroxol hydrochloride is a mucolytic agent developed by Boehringer Ingelheim in Germany. It was first marketed in Germany in the early 1980s, and then in France, Italy, Japan, Spain and many other countries. As a new generation mucolytic agent, ambroxol can improve sputum excretion, and has the effect of promoting lung surface active substances, airway secretion and ciliary movement. Clinically, it can regulate the secretion of mucus and mucous pulp, activate the wiggle of cilia, easily dilute sputum, enhance the outward transport of mucus Chemicalbook, and facilitate the discharge. It can also promote the synthesis of lung surfactant, so as to maintain alveolar tension and ensure lung function indicators. Promote the penetration of antibiotics into tissues to increase the concentration and enhance the bactericidal effect; Antioxidant, reduce the release of inflammatory mediators to reduce the inflammatory response; In order to improve the efficacy of antispasmolytic drugs, it can cooperate with bronchial antispasmolytic substances. Therefore, this drug can be widely used in clinical for acute and chronic respiratory diseases accompanied by abnormal secretion of respiratory tract, especially for expectorant treatment of chronic bronchitis, neonatal respiratory distress and auxiliary treatment of lung surgery. It has the advantages of low toxicity, exact efficacy, and can produce good synergistic effect with antibiotics, and is one of the most commonly used expectorant drugs.