On the mechanism of action of theophylline and caffeine.

Important developments in our understanding of the mechanism of action of methylxanthines have taken place in the last 10 years. A brief overview of these developments is provided below and the author concludes that the common view that theophylline (and caffeine) acts by raising the levels of cyclic AMP is generally untenable. Instead, many of the actions of the methylxanthines can be explained on the basis of their being antagonists of endogenous adenosine. However, the mechanism behind the antiasthmatic effects of xanthines still remains unknown and further research is necessary.