Theophylline can reduce smooth muscle tone and airway dilation; it can promote the release of endogenous epinephrine and norepinephrine and airway smooth muscle relaxation; it inhibits the release of calcium ions from the endoplasmic reticulum of smooth muscle and reduces the intracellular calcium ion concentration and produces airway dilation. Theophylline has a stronger relaxing effect on smooth muscle, but not as strong as beta agonists. Indications: 1. Used for bronchial asthma, acute bronchitis, asthmatic bronchitis, obstructive emphysema, etc. to relieve wheezing symptoms. It is also indicated for chronic bronchitis and emphysema with symptoms of bronchospasm.2. It can be used in patients with cardiogenic asthma, cardiogenic edema and acute cardiac insufficiency.3. It can also be used in patients with biliary colic.