The document outlines preclinical screening methods for evaluating anti-asthmatic drugs, detailing the pharmacological actions of bronchodilators and various in vitro and in vivo drug testing procedures. It emphasizes asthma's characteristics, types, symptoms, and the mechanisms of different therapeutic agents used in treatment. Key studies involve determining spasmolytic activity, pulmonary responses, and bronchospasmolytic efficacy in animal models, ultimately discussing the main categories of agents for asthma relief.