Lopressor (Metoprolol)
Metoprolol is a beta-adrenergic blocking drug which operates on the sympathetic nervous system, a portion of the involuntary nervous system. The sympathetic nervous system increases frequency of heart beat. Metoprolol is necessary for the treatment of abnormally rapid heart rhythms because it decreases the heart rate by inhibiting the action of these nerves. As metoprolol also decreases the force of heart muscle contraction and lowers blood pressure it diminishes heart muscle oxygen demand. Since angina appears when oxygen demand of the heart exceeds supply, metoprolol can help in treatment angina.