Beta Blockers

Want to fully understand how beta blockers work, and when they are used? This table will simplify these for you.

This Free table can simply the category of Beta Blocker medications down into simple and understandable terms, so you won’t forget it.

Beta Blockers 2

BETA-BLOCKING DRUGS ( Classification, Subgroups, and Mechanisms)

  1. Receptor selectivity

Beta1-receptor selectivity (β1 block > β2 block) is a property of acebutolol, atenolol, esmolol, metoprolol, and several other β blockers. This property may be an advantage when treating patients with asthma. Nadolol, propranolol, and timolol are typical nonselective β blockers. Labetalol and carvedilol have combined α- and β-blocking actions. These drugs are optically active, and different isomers have α- or β-blocking action. Nebivolol has vasodilating action in addition to β1-selective antagonism.

  1. Partial agonist activity

Partial agonist activity (“intrinsic sympathomimetic activity”) may be an advantage in treating patients with asthma because these drugs (eg, pindolol, acebutolol)—at least in theory—are less likely to cause bronchospasm. In contrast, full antagonists such as propranolol are more likely to cause severe bronchospasm in patients with airway disease.

  1. Local anesthetic activity—Local anesthetic activity

(“membrane-stabilizing activity”) is a disadvantage when β blockers are used topically in the eye because it decreases protective reflexes and increases the risk of corneal ulceration. Local anesthetic effects are absent from timolol and several other β blockers that are useful in glaucoma.

  1. Pharmacokinetics—Most of the systemic agents have been developed for chronic oral use, but bioavailability and duration of action vary widely .Esmolol is a short-acting ester β blocker that is used only parenterally. Nadolol is the longest-acting β blocker. Acebutolol, atenolol, and nadolol are less lipid-soluble than other β blockers and probably enter the central nervous system (CNS) to a lesser extent.

 

 

Effects and Clinical Uses

Most of the organ-level effects of β blockers are predictable from blockade of the β-receptor–mediated effects of sympathetic discharge. The clinical applications of β blockade are remarkably broad (see the Drug Summary Table). The treatment of open-angle glaucoma involves the use of several groups of autonomic drugs as well as other agents .The cardiovascular applications of β blockers—especially in hypertension, angina, and arrhythmias—are extremely important. Treatment of chronic (not acute) heart failure has become an important application of β blockers. Several large clinical trials have shown that some, but not all, β blockers can reduce morbidity and mortality when used properly in heart failure (see Chapter 13). Labetalol, carvedilol, and metoprolol appear to be beneficial in this application. Pheochromocytoma is sometimes treated with combined α- and β-blocking agents (eg, labetalol), especially if the tumor is producing large amounts of epinephrine as well as norepinephrine.

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