Interesting article on phosphodiesterase inhibitors, from The International Journal of PharmTech Research:

http://sphinxsai.com/ptvol4/pdf_vol4/pt=30%20(1148-1160).pdf

PHOSPHODIESTERASE INHIBITORS: THEIR ROLE AND IMPLICATIONS

such as cAMP and cGMP and thus have pivotal roles in cellular functions. PDE inhibitors such as theophylline have been employed as anti-asthmatics since decades and numerous novel selective PDE inhibitors are currently being investigated for the treatment of diseases such as Alzheimer’s disease, erectile dysfunction and many others. This review attempts to elucidate the pharmacology, applications and recent developments in research on PDE inhibitors as pharmacological agents.
Keywords: Phosphodiesterases, Phosphodiesterase inhibitors.