Metoprolol (Lopressor / Toprol XL) is a beta blocker used to treat high blood pressure. This medication works by blocking the effects of the hormone adrenaline. Summary. Metoprolol (Lopressor, Toprol XL) is a beta-adrenergic blocking agent drug, which blocks the action of the sympathetic nervous system (a portion of the involuntary nervous system). Toprol-XL (metoprolol succinate) is a beta-blocker that affects the heart and circulation (blood flow through arteries and veins). Toprol-XL is used to treat angina (chest pain) and hypertension (high blood pressure). INDICATIONS Hypertension. TOPROL-XL is indicated for the treatment of hypertension, to lower blood pressure. Lowering blood pressure lowers the risk of fatal and non-fatal cardiovascular events, primarily strokes and myocardial infarctions. Official Health Care Professional Web site for TOPROL-XL® (metoprolol succinate) extended-release tablets, a hypertension medication. High Blood Pressure. Some people may not know that they have high blood pressure, also called hypertension. Some may not know until they have a heart attack or stroke. How to use Toprol XL. See also Warning section. Take this medication by mouth as directed by your doctor, usually once daily. Some brands of this medication (those containing metoprolol tartrate. Find information about once-a-day TOPROL-XL® (metoprolol succinate) Extended-Release Tablets and learn more about high blood pressure. TOPROL-XL is indicated for the treatment of hypertension, to lower blood pressure. Lowering blood pressure lowers the Lowering blood pressure lowers the risk of fatal and non-fatal cardiovascular events, primarily strokes and myocardial infarctions. TOPROL-XL is an extended-release tablet intended for once daily administration. For treatment of hypertension and angina, when switching from immediate-release metoprolol to TOPROL-XL, use the same total daily dose of TOPROL-XL.