Oxyphenonium is an anticholinergic drug. It exerts its action by inhibiting muscarinic (cholinergic) receptors on smooth muscles, cardiac muscles and prevents the effect of Acetylcholine. Inhibition of Acetylcholine produces relaxation of smooth muscles and prevents the muscle spasm in irritable bowel syndrome. Oxyphenonium also has a direct relaxant effect on smooth muscle. It also inhibits gastrointestinal propulsive movement and decreases gastric acid secretion and control bronchial, pharyngeal and tracheal secretions. It also possesses nicotinic blocking activity and interferes with ganglionic or neuromuscular transmission. It cross the BBB poorly and does not produce CNS effect.