Differences in the Basic Pharmacology of Beta-Blocking Agents

Abstract

β-Blockers are important in the treatment of arterial hypertension, coronary heart disease, cardiac arrhythmias and heart failure. Their effects are mediated by the blockade of various types of β- and α-receptors, and compounds have been developed to specifically inhibit them. Nonselective β-blockers (e.g. propranolol, nadolol, penbutolol and carvedilol) differ from β1-selective blockers (e.g. metoprolol, atenolol, bisoprolol and nebivolol). Selectivity is never absolute and all β-blockers can cause problems in allergic asthma including serious side effects and death. The clinical advantage of selectivity appears to be meager, as only few patients with chronic obstructive pulmonary disease seem to benefit from increased tolerability. Another important feature is the intrinsic-sympathomimetic activity of some compounds (e. g. pindolol or oxprenolol), which is associated with negative outcomes. Vasodilation by additional α-blockade as seen with carvedilol results in metabolic neutrality and superior tolerability especially in patients with hypertension, heart failure and pAVK. Nebivolol is a β-blocker which leads to NO generation in the endothelium, and, thus, to NO-dependent vasodilation, and thus has a strong antihypertensive profile.