Isosorbide is composed of isosorbide nitrate, and nitroglycerin is a nitrate drug. The major difference is that one is a medium-acting formulation of nitrate, and the other is a short-acting formulation of nitrate. For example, nitroglycerin is mainly used in clinical practice to stop painful episodes, when angina attack, you can take this drug under the tongue, usually 1-2 minutes after the sublingual can take effect, about 4-5 minutes blood pressure concentration can reach the peak, the effective effect time can last about 1 hour. Like isosorbide nitrate generally takes effect 15-20 minutes after taking the drug, the blood pressure concentration can reach the peak in 30-120 minutes, and the duration of action can be maintained for 4 hours. Therefore, its duration of action is longer than that of nitroglycerin.