Adrenergic beta-antagonist

Adrenergic beta-receptor blockaders (beta-blockers) are "drugs that bind to but do not activate beta-adrenergic receptors thereby blocking the actions of beta-adrenergic agonists. Adrenergic beta-antagonists are used for treatment of hypertension, cardiac arrhythmias, angina pectoris, glaucoma, migraine headaches, and anxiety".

Beta-blockers vary within the class regarding their properties. Beta-blockers that have low intrinsic sympathomimetic activity (ISA), low membrane stabilizing activity, high beta 1-selectivity, and high lipophilicity may be more effective.

Pharmacogenomics
Regarding the treatment of heart failure, there is conflicting evidence whether beta-blockers are as effective in African-American patients as in Anglo patients. This may be due to a polymorphism in African-American patients of the G-protein-coupled receptor kinase (GRK5) (OMIM) that confers a natural "genetic beta-blockade".

Variation adrenergic receptor genotype may also influence effectiveness.

Beta-blockers such as metoprolol that are metabolized by cytochrome P-450 2D6 allele and may have more drug interactions and inherited variations in metabolism.

Classification
Generically available beta-blockers, which subclassify based on selective aspects of their action, include: include:
 * Acebutolol
 * Atenolol
 * Bisoprolol
 * Metoprolol
 * Nadolol
 * Propranolol
 * Timolol

They further divide by frequency of dosing, cost, and other factors.

Cardioselective/beta 1-selectivity
Generic beta-blockers with beta 1-selectivity: Non-generic:
 * Atenolol
 * Renally excreted
 * Hydrophilic
 * May require twice daily dosing
 * Bisoprolol
 * Metoprolol
 * Hepatically metabolized by cytochrome P-450 2D6 allele
 * Lipophilic
 * Acebutolol
 * Betaxolol

Non-selective
Non-selective drugs include propranolol, timolol, nadolol, pindolol, penbutolol, and carteolol.

Intrinsic sympathomimetic activity
Generic beta-blockers with intrinsic sympathomimetic activity (less resting bradycardia and lipid changes): Non-generic:
 * Acebutolol
 * Pindolol
 * Penbutolol

Beta-blockers with alpha blocking activity
Generic beta-blockers with alpha blocking activity (more orthostatic hypotension):
 * Carvedilol
 * Labetalol

Clinical uses
The individual beta-blockers have been compared in the treatment of various diseases.

Coronary heart disease
Adrenergic beta-antagonists were first shown to be effective in 1981.

Meta-analyses have concluded that metoprolol may or may not be the best beta-blocker for secondary prevention of myocardial infarctions.

Heart failure
Beta-blockers were originally thought to be contraindicated in patients with heart failure. However, trials eventually showed benefit of the drugs.Metoprolol can benefit patients with heart failure.

Two cohort studies suggest that atenolol and carvedilol may be more effect than metoprolol for the treatment of heart failure.

Drugs with intrinsic sympathomimetic activity may have less benefit A systematic review of randomized controlled trials concluded "metoprolol, carvedilol, and bisoprolol all exhibited statistically significant mortality rate reductions compared with placebo, the data were inconclusive for nebivolol or atenolol" and "for every heart rate reduction of 5 beats/min with β-blocker treatment, a commensurate 18% reduction in the risk for death occurred."

Hypertension
Beta-blockers may not be a good first choice medication in treating hypertension - at least for patients without coronary heart disease. A meta-analysis has concluded that the more the drug lowers the pulse rate, the lower the benefit of the drug.

Beta-blockers may be less effective than diuretics in the treatment of elderly patients with hypertension due to reduced ability to prevent coronary heart disease.