A classification of beta-blockers is given in Fig. 3. Cardio-selectivity indicates that the drug chiefly blocks beta-1 Propranolol Nadolol Sotalol Timolol Teratolol (E) *Carvedilol Bucindolol
receptors in the heart and partially spares beta-2 receptors in the lungs and blood vessels. Large doses of all beta-blocking agents block beta-2 receptors, thus, cardioselec-tive drugs are not cardiospecific. Bisoprolol is more cardioselective than metoprolol or atenolol. The classifica¬tion into cardioselective and nonselective is important, but oversimplified.