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Related Concept Videos

Adrenergic Agonists: Therapeutic Uses01:30

Adrenergic Agonists: Therapeutic Uses

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Adrenergic agonists have diverse therapeutic uses across various medical conditions and emergencies.
Emergency and Intensive Care Unit (ICU) applications: Pressor agents increase blood pressure, heart rate, and contractility in shock and organ failure situations. Dopamine can induce vasodilation and stimulate adrenoceptors. Endogenous catecholamines are effective in treating cardiogenic shock. α2-agonists like clonidine can reverse anesthesia-induced hypertension.
Allergies and...
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Adrenergic Agonists: Direct-Acting Agents01:30

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Drugs that mimic the action of endogenous catecholamines like noradrenaline and adrenaline are called adrenergic agonists or sympathomimetics. Based on their mechanism of action, sympathomimetics can be classified as direct-, indirect-, or mixed-acting sympathomimetics. Direct-acting adrenergic agonists activate adrenoceptors without affecting presynaptic neurons, making them independent of neuronal catecholamine-depleting agents like reserpine and guanethidine.
These agents can be classified...
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Adrenergic Agonists: Therapeutic Classification01:18

Adrenergic Agonists: Therapeutic Classification

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Adrenergic agonists can be classified based on their therapeutic uses and mechanisms of action. They serve various purposes in clinical applications.
Vasopressor or pressor agents: They increase blood pressure and function as cardiac stimulants. Examples include endogenous catecholamines (norepinephrine and dopamine) and synthetic agents (phenylephrine).
Bronchodilators: β2-agonists can relax bronchial muscles and widen airways. They are commonly used for treating obstructive pulmonary...
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Adrenergic Antagonists: Chemistry and Classification of ɑ-Receptor Blockers01:17

Adrenergic Antagonists: Chemistry and Classification of ɑ-Receptor Blockers

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Adrenergic antagonists, or sympatholytics, inhibit adrenoceptor activation driven by catecholamines or agonists. Based on their adrenoceptor specificity, adrenergic blockers can be categorized into two primary groups: α-adrenergic blockers (α-blockers) and β-adrenergic blockers (β-blockers). α-blockers interact with α1 and α2 subtypes of α-adrenoceptors.
Nonselective α-blockers: Nonselective α-blockers contain haloalkylamine or imidazoline...
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Adrenergic Antagonists: Pharmacological Actions of ɑ-Receptor Blockers01:22

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α-Adrenergic antagonists, known as α-blockers, exert their effects by inhibiting α-adrenoceptors, leading to specific physiological actions. α1-blockers and α2-blockers have distinct pharmacological actions and therapeutic applications.
α1-blockers: These drugs inhibit α1-adrenoceptors on smooth muscle cells, resulting in vasodilation. This vasodilation lowers blood pressure, making α1-blockers valuable in treating hypertension. Additionally,...
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Adrenergic Agonists: Chemistry and Structure-Activity Relationship01:16

Adrenergic Agonists: Chemistry and Structure-Activity Relationship

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Adrenergic agonists' structure-activity relationship (SAR) determines their selectivity and efficacy. These agonists comprise a phenylethylamine moiety with an aromatic ring and an ethylamine side chain.
Aromatic ring substitutions: Substituting the aromatic ring with –OH groups at positions 3 and 4 yields catecholamines (e.g., epinephrine), which have a high affinity for adrenoceptors. Hydrogen bonding between –OH groups and receptors enhances adrenergic activity.
Separation of...
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Related Experiment Video

Updated: Mar 2, 2026

Assessment of Vascular Tone Responsiveness using Isolated Mesenteric Arteries with a Focus on Modulation by Perivascular Adipose Tissues
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Alpha-2 Agonists.

Viet Nguyen1, Dawn Tiemann1, Edward Park2

  • 1Department of Anesthesiology, LSUHSC-NO, 1542 Tulane Avenue, Room 659, New Orleans, LA 70112, USA.

Anesthesiology Clinics
|May 21, 2017
PubMed
Summary
This summary is machine-generated.

Alpha-2 agonists modulate central and peripheral nervous systems, providing sedation and analgesia with a favorable safety profile. These agents, including clonidine and dexmedetomidine, are valuable in anesthesia and intensive care settings.

Keywords:
Alpha-2 adrenoreceptorsClonidineDexmedetomidineDorsal hornLocus coeruleusMedullospinal tractsPonsPremedication

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Area of Science:

  • Anesthesiology
  • Pharmacology
  • Neuroscience

Background:

  • Alpha-2 adrenergic receptors are widely distributed in the central and peripheral nervous systems.
  • Key locations include the locus coeruleus, medullospinal tracts, ventrolateral medulla, and spinal dorsal horn.

Purpose of the Study:

  • To review the neuromodulatory effects of alpha-2 agonist agents.
  • To highlight the clinical applications of clonidine and dexmedetomidine in anesthesia.

Main Methods:

  • Review of literature on alpha-2 adrenergic receptor agonists.
  • Analysis of pharmacological effects and clinical uses in anesthesiology.

Main Results:

  • Alpha-2 agonists induce sedation, analgesia, vasodilatation, and bradycardia.
  • These agents have minimal impact on respiratory drive, contributing to their safety.
  • Clonidine and dexmedetomidine are primary examples with diverse anesthetic applications.

Conclusions:

  • Alpha-2 agonists are effective for sedation, analgesia, and as adjuncts in general and regional anesthesia.
  • Their safety profile makes them suitable for intensive care and premedication.