Tenorminis a cardioselective beta-adrenoblocker. It is based on a substance called Atenolol, which blocks nerve impulses, which leads to a decrease in the frequency and strength of the heartbeat. Atenolol has antihypertensive (lowers pressure), antianginal (eliminates the symptoms of myocardial ischemia) and antiarrhythmic (eliminates heart rhythm disturbances) by action.