Correlation between in vitro Cyclic Adenosine Monophosphate Phosphodiesterase Inhibition and in vivo Anti-Inflammatory Effect

We tested the hypothesis that topical adenosine monophosphate phosphodiesterase (cAMP PDE) inhibitors are anti-inflammatory. These can be shown by a correlation between PDE inhibitory and anti-inflammatory function of a series of known PDE inhibitors. The effect of various cAMP PDE inhibitors on PDEs isolated from HaCaT cells was first investigated. These compounds were then tested as anti-irritants against topical 8% Balsam of Peru. A direct correlation was observed between the in vitro EC 50 values for PDE inhibition and the in vivo anti-inflammatory potential with a correlation coefficient of r = 0.79. These results stress the value of PDE inhibitors as anti-inflammatory agents in topical use, and also demonstrate that the in vitro PDE assay can be used to predict in vivo anti-inflammatory potential.