Table 1: Summary of benefits and limitations of novel bronchodilators.

Drug class Benefits Limitations -agonists Rapid airway relaxation Selective for -AR; decreased systemic effects Receptor desensitization Receptor downregulation Refractory bronchoconstriction Asthma-related death PDE inhibitors Increase cAMP generated endogenously Enhance -AR effects Selectivity for subtypes specific to lung Oral delivery Complex dosing and metabolism Systemic side effects Potential adenylyl cyclase and/or -AR desensitization Phytotherapeutics Airway relaxation Acute and chronic effects Reduces inflammation and remodeling Increased patient compliance Mechanisms of action are not clearly defined Potential interaction with other drugs Difficulty standardizing source and dosing Bitter tastants Novel target—may augment traditional therapies due to cAMP-independence Mechanisms of action are not clearly defined Chloride channel modulators Novel target—may augment traditional therapies May address neuronal components of airway tone Mechanisms of action are not clearly defined Method of delivery Interaction with airway epithelium (mucous production) Systemic side effects