Theophylline: multiple mechanism of action

• Non selective phosphodiesterase inhibition: bronchodilation primarily attributed to increase in cAMP* 
• Adenosine receptor blockade: additional bronchodilatory effect 
• Promotes apoptosis of neutrophils and eosinophils
• Activation of histone deacetylase (HDAC):

* Increase in cAMP can mediate other effects:

• Reduced expression of proinflammatory genes
• Increase in interleukin 10; a antiinflammatory cytokine levels