Oxybutynin virker som en kompetitiv antagonist for acetylkolin på post - ganglionære, muskarine receptorer, hvilket medfører en afslapning af glat muskulatur i blæren.
Mechanism of action: oxybutynin acts as a competitive antagonist of acetylcholine at post-ganglionic muscarinic receptors, resulting in relaxation of bladder smooth muscle.