IBMX is a widely-used non-specific inhibitor of cyclic AMP and cyclic GMP phosphodiesterases (PDEs) (IC50 = 19, 50, 18, 13, 32, 7, and 50 μM for PDE1, PDE2, PDE3, PDE4, PDE5, PDE7, and PDE11, respectively). PDE8A, PDE8B, and PDE9 are insensitive to IBMX. By inhibiting PDEs, IBMX increases cellular cAMP and cGMP levels, activating cyclic-nucleotide-regulated protein kinases. Methylxanthines, including IBMX, caffeine, and theophylline, bind adenosine receptors, typically antagonizing the suppressive effects of natural agonists.
