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

Drug classBenefitsLimitations

-agonistsRapid airway relaxation
Selective for -AR; decreased systemic effects
Receptor desensitization
Receptor downregulation
Refractory bronchoconstriction
Asthma-related death

PDE inhibitorsIncrease 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

PhytotherapeuticsAirway 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 tastantsNovel target—may augment traditional therapies due to cAMP-independenceMechanisms of action are not clearly defined

Chloride channel modulatorsNovel 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