Theophylline, adenosine receptor targets

Beyond Viagra, there are a number of other PDE inhibitors that are used clinically. In fact, the classic drugs papaverine and dipyridamole were used clinically before their effects on PDEs were known. Caffeine and theophylline (a compound found in tea) are also PDE inhibitors. However, all of these drugs most likely have multiple targets, making conclusions regarding the roles of PDEs in processes that are sensitive to these agents difficult to interpret. Certainly, some of their effects are due to their actions on adenosine receptors. 

Purine receptors Adenosine, AMP, ADP and ATP can act extracellularly as hormones or transmitters, too In particular, adenosine receptors that occur in the heart, the brain, and the lung are the targets of theophylline and caffeine. Adenosine itself is being used for the treatment of a special type of cardiac arrhythmia. 

Adenosine receptors are targeted by drags such as theophylline and caffeine. 

---