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Presynaptic Adrenergic Release Inhibitor
Aka: Presynaptic Adrenergic Release Inhibitor, Alpha Adrenergic Central Agonist, Central Adrenergic Agonist, Central Alpha 2 Adrenergic Agonist, Peripheral Acting Presynaptic Adrenergic Antagonist, Peripheral Presynaptic Adrenergic Antagonist, Peripheral Presynaptic Alpha Adrenergic Antagonist
- See Also
- Sympathetic Nervous System
- Alpha Adrenergic Receptor
- Beta Adrenergic Receptor
- Guanabenz (Wytensin)
- Guanfacine (Tenex)
- Alpha Methyldopa (Aldomet)
- Clonidine
- Clonidine Withdrawal
- Clonidine Overdose
- Alpha Adrenergic Antagonist (e.g. Prazosin)
- Reserpine (Serpasil)
- Guanethidine (Ismelin)
- Guanadrel (Hylorel)
- 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 alpha-2 receptors that inhibit CNS sympathetic signals
- Results in increased parasympathetic effects and side effects
- Peripheral Acting Adrenergic Antagonists
- Block peripheral Norepinephrine release
- 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)
- Guanabenz (Wytensin)
- Guanfacine (Tenex)
- Selective Preparations: Alpha-2a (for Opioid Withdrawal symptoms)
- Lofexidine
- 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
- Agents
- Reserpine (Serpasil)
- Guanethidine (Ismelin)
- Guanadrel (Hylorel)