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Author: Admin | 2025-04-28
Adrenergic antagonists are also referred to as sympatholytics because they lyse, or block, the effects of the sympathetic nervous system. They react with specific adrenergic receptor sites without activating them, thus preventing the typical manifestations of SNS activation.These drugs occupy the adrenergic receptor site so released norepinephrine can be prevented from activating the receptor.Adrenergic antagonists have varying degrees of specificity and are therefore classified into five: nonselective adrenergic antagonists, nonselective alpha- and beta- adrenergic antagonists, and selective alpha1– and beta-adrenergic antagonists.Table of Common Drugs and Generic NamesHere is a table of commonly encountered adrenergic antagonists, their generic names, and brand names:ClassificationGeneric NameBrand NameNonselective Adrenergic Blocking AgentsamiodaroneCordaronecarvedilolCoreglabetalolNormodyne, TrandateNonselective Alpha-Adrenergic Blocking AgentphentolamineRegitineAlpha1-Selective Adrenergic Blocking AgentsalfuzosinUroxatraldoxazosinCarduraprazosinMinipresstamsulosinFlomaxterazosinHytrinNonselective Beta-Adrenergic Blocking AgentsnebivololBystolicnadololCorgardpropranololInderaltimololBlocarden, TimopticBeta1-Selective Adrenergic Blocking AgentsbisoprololZebetaesmololBreviblocmetoprololLopressor, Toprol XLDisease Spotlight: Cardiorespiratory-related conditions, Benign Prostatic HypertrophyNonselective adrenergic antagonists are primarily used to treat cardiac-related conditions. Completely opposite with sympathomimetics, these drugs are ideal for hypertension and heart failure because they reduce the rate and conduction of the heart, relieving it from too much workload.Of all nonselective alpha adrenergic antagonists, only phentolamine (Regitine) is used. This drug classification has its use limited because of more specific drugs.Selective alpha1-receptor adrenergic antagonists can improve urine flow in male patients and are used as treatment for benign prostatic hypertrophy (BPH). This is because they can block smooth muscle receptors in the genitourinary tract which leads to relaxation of prostate and bladder.Nonselective beta-adrenergic antagonists are used to treat CV problems and to prevent reinfarction after MI.Selective beta1-receptor adrenergic antagonists is more advantageous than nonselective beta-blockers because they don’t block beta2-receptors, allowing bronchodilation. This class is preferred for smokers and those with respiratory problems. They are also used for treating hypertension, angina, and cardiac arrhythmias.Nonselective Adrenergic Blocking AgentsDescriptionNonselective adrenergic blocking agents block all receptors (alpha- and beta-receptors). These drugs are primarily used to treat cardiac-related conditions.Popular example under this class include labetalol and carvedilol.Therapeutic ActionThe desired and beneficial actions of nonselective adrenergic antagonists are as follows:Nonselective adrenergic antagonists competitively block the effects of norepinephrine at both alpha and beta receptors throughout the SNS. This results in lower blood pressure, slower pulse rate, and increased renal perfusion with decreased renin levels.IndicationsNonselective adrenergic antagonists are indicated for the following medical conditions:Most nonselective adrenergic antagonists (e.g. labetalol, carvedilol, etc.) are indicated to treat essential hypertension, alone or in combination with diuretics. Others (e.g. amiodarone) is for emergency cases and is only used as an antiarrhythmic.Here are some
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