The differences between nitroglycerin and isosorbide nitrate include composition, duration of action, and bioavailability. 1. Composition: the main component of nitroglycerin is nitroglycerin, and the end product is glycerol. The main component of isosorbide nitrate is isosorbide nitrate, and the end products are isosorbide, dextro-sorbide and so on. 2. Time of action: Nitroglycerin reaches its maximum effect in about 5 minutes after sublingual administration, and the effect lasts for 10 to 30 minutes. Isosorbide nitrate reaches the maximum effect about 1 hour after taking and lasts for 2 to 4 hours. 3. Bioavailability: The bioavailability of nitroglycerin can reach up to 80%, while isosorbide nitrate has obvious hepatic first-pass effects, with a bioavailability of up to 40% to 60%. The adverse effects of these two drugs are similar, such as vasodilatory headache, dizziness, palpitations (rapid heartbeat, often accompanied by panic), postural hypotension and so on. It is contraindicated in people who are allergic to both drugs, people with severe hypotension, and so on. Individual differences exist in the specific use of the drug, and it is recommended to follow the doctor’s instructions to use the drug.