Non-Selective Phosphodiesterase (None)

Non-selective phosphodiesterase inhibitors are compounds that inhibit multiple PDE isoenzymes rather than targeting a specific subtype, leading to broad effects on cellular signaling pathways. By inhibiting these enzymes non-selectively, they increase intracellular cAMP and/or cGMP levels, resulting in relaxation of bronchial smooth muscle, vasodilation, bronchodilation, anti-inflammatory effects and strengthened heart contractions. Examples include caffeine and theophylline. Their lack of selectivity leads to broader systemic effects compared with newer selective agents targeting individual isoforms such as PDE3 or PDE5.

Inhibition of multiple phosphodiesterase isoforms, increasing intracellular cAMP and/or cGMP levels, leading to smooth muscle relaxation, bronchodilation, vasodilation, anti-inflammatory effects, and increased cardiac contractility.