II. Background
-
Adrenergic Receptor
Agonists increase Blood Pressure
- Alpha 1 Adrenergic Receptor binding increases Vasoconstriction
- Beta 1 Adrenergic Receptor binding increases myocardial contractility
- Presynaptic Adrenergic Release Inhibitors lower Blood Pressure
- Central Acting Adrenergic Agonists
- Activate central alpha-2 receptors that inhibit CNS sympathetic signals
- Results in increased parasympathetic effects and side effects
- Peripheral Acting Adrenergic Antagonists
- Block peripheral Norepinephrine release
- Central Acting Adrenergic Agonists
III. Preparations: Central Acting Adrenergic Agonists
- Mechanism
- See Alpha Adrenergic Receptor
- Bind central alpha-2 receptors (vasomotor receptors) to inhibit sympathetic outflow
- Decreases Peripheral Vascular Resistance (and Blood Pressure)
- Decreases Heart Rate
- Non-selective Preparations
- Clonidine (Catapres)
- Alpha Methyldopa (Aldomet)
- Guanfacine (Tenex)
- Guanabenz (Wytensin, no longer available in U.S.)
- Selective Preparations: Alpha-2a (for Opioid Withdrawal symptoms)
IV. Preparations: Peripheral Acting Adrenergic Antagonists
- Mechanism
- Peripheral Presynaptic Adrenergic Antagonists block Norepinephrine release from postganglionic nerve terminals
- Contrast with Postsynaptic Adrenergic Antagonists that block peripheral alpha receptors
- Nonselective post-synaptic Alpha Antagonists (Terazosin, Doxazosin, Prazosin) result in general peripheral vasodilation
- Selective Alpha-1a Antagonist (Tamsulosin, Alfuzosin, Silodosin) primarily result in Urethral region relaxation
- Agents
V. References
- Olson (2020) Clinical Pharmacology, MedMaster, Miami, p. 64-5
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Related Studies
Concepts | Pharmacologic Substance (T121) |
SnomedCT | 349933002, 372623002 |
English | Central alpha-adrenocep agon., Central alpha-adrenoceptor agonist, Central alpha-adrenoceptor agonist (product), Central alpha-adrenoceptor agonist (substance) |
Spanish | agonista central alfa adrenérgico (producto), agonista central alfa adrenérgico (sustancia), agonista central alfa adrenérgico, agonista de adrenorreceptor alfa central (sustancia), agonista de adrenorreceptor alfa central |