Synthesis Methods of Loratadine and Its Clinical Application Comparison in Antihistamines

Loratadine is a second-generation antihistamine widely used in treating allergic diseases such as allergic rhinitis, urticaria, and conjunctivitis. Compared to first-generation antihistamines, loratadine has fewer central nervous system side effects, such as drowsiness and cognitive impairment, and exhibits prolonged efficacy. This paper comprehensively reviews the chemical structure, mechanism of action, and organic synthesis methods of loratadine. Loratadine’s tricyclic structure and selective binding to peripheral histamine H1 receptors allow it to effectively relieve allergic symptoms at low doses while minimizing side effects. The article also analyzes various classical and improved loratadine synthesis routes, comparing their advantages and disadvantages in terms of reaction conditions, yields, and environmental impact. By introducing novel catalysts and optimizing reaction conditions, the improved synthesis methods not only enhance yields and cost-effectiveness but also reduce environmental pollution. Additionally, this paper discusses the comparison of loratadine with other antihistamines in terms of efficacy and safety, highlighting its significant clinical advantages. Nonetheless, there remains a need for further optimization of its synthesis process and exploration of its potential in personalized treatment to meet the needs of different patients.