ABSTRACT
Theophylline is a kind of methyl purine drug extracted from tea with the eect of smooth muscle relaxation, coronary artery dilatation and central nervous system excitement. It is used in clinical mainly as a bronchodilator [1]. The blood concentration of theophylline in vivo showed peak valley phenomenon obviously, which results in a series of adverse reactions. In order to avoid the side eect, the sustained drug release is often needed in clinical [2].
