Toprol is part of a class of drugs called beta-adrenergic blocking agents, or beta blockers for short. As the name implies, beta blockers block beta receptors in the body. Beta receptors are located in a number of places within the body, including the heart and blood vessels. These receptors are what stress hormones (such as adrenaline) attach to, and they cause certain reactions in the body, such as an increase in:
Toprol helps to block a specific type of beta receptor called beta-1 receptors. By blocking these receptors, Toprol causes the reverse effect of these stress hormones. It decreases heart rate and both systolic and diastolic blood pressure, as well as the workload of the heart. This means that the heart requires less blood and oxygen to work properly. The medication also increases the efficiency of the heart, allowing more blood to be pumped out to the rest of the body.
Toprol is a beta-1 selective (or cardioselective) beta blocker. This means that it mostly blocks beta-1 receptors, especially at normal doses. However, it can block beta-2 receptors in the lungs to some extent, especially at higher dosages. This can lead to breathing problems, especially in people with asthma or other similar conditions.
Effects of Toprol
A blood pressure reading consists of two numbers -- for example, 120/80. The top number is known as the systolic blood pressure, and the bottom number is the diastolic blood pressure. In clinical studies, people taking Toprol were able, on average, to decrease systolic blood pressure by 6 mmHg to 8 mmHg and diastolic blood pressure by 4 mmHg to 7 mmHg. The higher the dose, the greater the drop in blood pressure tended to be. By lowering blood pressure, Toprol can also decrease the risks that accompany long-term high blood pressure(see Effects of High Blood Pressure). By decreasing the workload of the heart, Toprol can also decrease the number of angina attacks and increase exercise tolerance.
For people with congestive heart failure, the effects of Toprol on the heart and blood vessels have been shown to result in a decrease in hospitalizations and loss of life from congestive heart failure.
Written by/reviewed by: Kristi Monson, PharmD;Arthur Schoenstadt, MD
Last reviewed by: KristiMonson, PharmD;
List of references (click here):
Toprol-XL [package insert]. Wilmington, DE: AstraZeneca LP;2007 July.
Food and Drug Administration, Center for Drug Evaluation and Research. Electronic orange book: approved drug products with therapeutic equivalence evaluations. FDA Web site. Available at: http://www.fda.gov/cder/ob/. Accessed January 9, 2009.
Briggs GG, Freeman RK, Yaffe SJ. Drugs in Pregnancy and Lactation. 8th ed. Philadelphia (PA): Lippincott Williams & Wilkins;2008.
National Library of Medicine (US). Drugs and Lactation Database (LactMED). NLM Web site. Available at: http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT. Accessed January 9, 2008.
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