Sympathomimetics
Sympathomimetics - Related Videos
01:37
Hypothalamic-Pituitary Axis
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2019
The response to stress—be it physical or psychological, acute or chronic—involves activation of the Hypothalamic-Pituitary-Adrenal (HPA) axis. The HPA axis is part of the neuroendocrine system because it involves both neuronal and hormonal communication. Its function is to regulate homeostatic systems—metabolic, cardiovascular, and immune—providing the necessary means to respond to a stressor. What Happens During Stress In response to stress, the neurons in the hypothalamus release...
09:02
Percutaneous Hepatic Perfusion (PHP) with Melphalan as a Treatment for Unresectable Metastases Confined to the Liver
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Cited by 12 •
2016
In this manuscript, we describe percutaneous isolated hepatic perfusion with simultaneous chemofiltration as treatment for unresectable liver metastases. This procedure is performed under general anaesthesia in the angiosuite by an experienced team, consisting of an interventional radiologist, a clinical perfusionist and anaesthesiologist.
FAQs
Direct-acting agents exert effects by stimulating adrenergic alpha or beta receptors. Indirect-acting agents increase norepinephrine availability, either by enhancing its release or reducing its reuptake. This distinction matters because the two strategies alter sympathetic signaling through different steps, helping pharmacologists relate a drug’s mechanism to its receptor-mediated effects and expected therapeutic use.
Receptor selectivity helps concentrate drug effects in pathways linked to a desired response. Alpha-receptor activity is associated with vasoconstriction, while beta-receptor activity can increase cardiac activity or promote bronchodilation. Greater selectivity can support more targeted treatment, whereas activity at additional receptor types may broaden physiological effects and increase the possibility of adverse outcomes.
Dose is an important determinant of outcome because sympathetic effects are not limited to a single tissue or receptor response. As dosing changes, the balance between desired actions, such as vasoconstriction or bronchodilation, and unwanted effects can also change. Pharmacology therefore considers dose alongside receptor selectivity when evaluating therapeutic usefulness and safety.
They are used in contexts where enhanced sympathetic effects provide a useful physiological response. Vasoconstriction supports treatment of hypotension and nasal congestion, bronchodilation is relevant to asthma, and sympathomimetic activity contributes to managing severe allergic reactions. These examples show how the same broad drug class can serve different clinical purposes through tissue-specific outcomes.
The preferred effect depends on the clinical problem being addressed. Vasoconstriction is relevant when the therapeutic goal involves raising vascular tone, as in hypotension, or reducing nasal congestion. Bronchodilation is more relevant when opening the airways is needed, such as in asthma. This comparison illustrates how tissue response guides pharmacologic application.
They provide a practical way to study how sympathetic activation is translated into tissue responses. Comparing direct receptor stimulation with altered norepinephrine availability connects drug mechanism to autonomic regulation. This knowledge also informs development of more targeted agents, where receptor selectivity is used to pursue useful effects while improving control over outcomes and adverse effects.