Hello, Metoprolol succinate comes as an extended-release oral tablet. When a drug is extended release, it means it releases into your body slowly. You usually take it once per day. Metoprolol tartrate is available as an immediate-release oral tablet. It does not stay in your body as long as Metoprolol succinate does, so you must take it multiple times per day. This drug also comes as a solution for injection that is used to treat unstable angina and arrhythmia. A healthcare provider gives you this injection, you do not give it to yourself. Both can use for control blood pressure. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Penchila Prasad Kandikattu