Theophylline is a phosphodiesterase inhibitor, which gives rise to higher intracellular levels of PKA and PKG. The increase in PKA and PKG activity is associated with smooth muscle relaxation and decreased inflammatory responses. Although it should be said that the anti-inflammatory effect is clinically not spectacular.
Theophylline is also considered a last-line agent due to its pharmacokinetic parameters which give it a narrow therapeutic window between effectiveness and toxicity. See also: therapeutic drug concentrations.
Also shown in the graphic are the additional theoretical benefits of β-agonists. See also: β-effect in lung.
Theophylline decreases intracellular AMP and GMP.
Extra info: After incorporation into the cell, theophylline inhibits the conversion of cAMP and cGMP. Thus decreasing the cellular levels of AMP and GMP
Theophylline acts on β-receptors.
Extra info: Theophylline is a phosphodiesterase inhibitor, thus does not work on β-receptors, but can work in cooperation with β-receptors to enhance PKA stimulation.