adrenergic (redirected from Alpha adrenergic)

adrenergic /ad·ren·er·gic/ (ad″ren-er´jik)

1. activated by, characteristic of, or secreting epinephrine or related substances, particularly the sympathetic nerve fibers that liberate norepinephrine at a synapse when a nerve impulse passes.

2. any agent that produces such an effect. See also under receptor.

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ad·re·ner·gic (dr-nûrjk)

adj.

1. Activated by or capable of releasing epinephrine or an epinephrinelike substance, especially in the sympathetic nervous system.

2. Having physiological effects similar to those of epinephrine.

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Adrenergic

Activated by adrenalin (norepinephrine), loosely applied to the sympathetic nervous system responses.

Mentioned in: Alpha 1 -Adrenergic Blockers, Antihypertensive Drugs

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adrenergic

[ad′rinur′jik]

Etymology: L, ad + ren; Gk, ergon, work

1 pertaining to sympathetic nerve fibers of the autonomic nervous system that liberate norepinephrine at a synapse where a nerve impulse passes.

2 See sympathomimetic. Compare antiadrenergic, cholinergic. See also sympathomimetic.

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adrenergic (ad´rinur´jik),

adj 1. transmitted by norepinephrine or activated by norepinephrine or the other sympathomimetic agents.
n 2. a term applied to nerve fibers that liberate epinephrine or norepinephrine at a synapse when a nerve impulse passes.
n 3. a drug that mimics the action of adrenergic nerves.

adrenergic agonists,

n.pl drugs that mimic the actions of norepinephrine, a neurotransmitter, resulting in stimulation of the sympathetic nervous system.

adrenergic blocking agent,

n See agent, adrenergic blocking.

adrenergic fibers,

n.pl See fibers, adrenergic.

adrenergic receptors,

n.pl See receptors, adrenergic.

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adrenergic

1. activated by, characteristic of, or secreting epinephrine or substances with activities similar to those of epinephrine. The term is applied to those nerve fibers of the sympathetic nervous system that release norepinephrine (and possibly small amounts of epinephrine) at a synapse when a nerve impulse passes.

2. an agent that acts like epinephrine. Called also sympathomimetic.

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adrenergic agents

sympathomimetic amines which exert their effects on adrenergic receptors of effector cells innervated by the sympathetic nervous system. The administration of these adrenergic agonists mimics the physiological effects of sympathoadrenal discharge.

adrenergic alpha-blockers, beta-blockers

see adrenergic blockade.

adrenergic amines

these are the sympathomimetic amines. They have similar but not identical structures and actions. Epinephrine, norepinephrine and isoproterenol are catecholamines but differ in their effects. Norepinephrine is primarily an activator of alpha-receptors whereas isoproterenol is a selective beta-receptor agonist. Epinephrine is an active agonist for both alpha- and beta-receptors. Ephedrine is the classical noncatecholamine sympathetic agonist.

adrenergic blockade

adrenergic blocking agents prevent the activation of adrenergic receptors. They may be alpha-blockers, e.g. ergot, or beta-blockers such as propranolol.

adrenergic blocking agent

a drug that blocks the secretion of epinephrine and norepinephrine at the postganglionic nerve endings of the sympathetic nervous system. By blocking these adrenergic substances, which cause constriction of blood vessels and increased cardiac output, adrenergic blocking agents produce a dilatation of the blood vessels and a decrease in cardiac output.

adrenergic nerves

see adrenergic (1) (above).

adrenergic nervous system

see sympathetic nervous system.

adrenergic receptors

class of receptors named after the action of adrenalin(e), the alternative name for epinephrine. Alpha receptors, which are stimulated by norepinephrine and blocked by agents such as phenoxybenzamine, are categorized into two classes, α₁ and α₂, which have different actions. α₁ adrenergic actions include contraction of the iris, decreased motility in the intestine, and potassium and water secretions from the salivary glands. α₂ adrenergic receptors inhibit adenylate cyclase, rather than activating it. Beta receptors, which are stimulated by epinephrine and blocked by agents such as propranolol, are also categorized into two types; β₁ adrenergic receptors, which produce lipolysis and cardiostimulation, and β₂ adrenergic receptors, which produce bronchodilatation and vasodilatation.

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adrenergic 

1. Relating to a neuron that is activated or capable of releasing adrenaline (epinephrine).

2. Having an effect similar to adrenaline (epinephrine).

3. Relating to drugs that mimic the effects of the sympathetic nervous system (sympathomimetic drugs).

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dobutamine hydrochloride

Pharmacologic class: Sympathomimetic, adrenergic

Therapeutic class: Inotropic

Pregnancy risk category B

Action

Stimulates beta₁-adrenergic receptors of heart, causing a positive inotropic effect that increases myocardial contractility and stroke volume. Also reduces peripheral vascular resistance, decreases ventricular filling pressure, and promotes atrioventricular conduction.

Availability

Injection: 12.5 mg/ml in 20-ml vials

⊘Indications and dosages

➣ Short-term treatment of cardiac decompensation caused by depressed contractility (such as during refractory heart failure); adjunct in cardiac surgery

Adults: 2.5 to 10 mcg/kg/minute I.V. as a continuous infusion, adjusted to hemodynamic response

Dosage adjustment

• Elderly patients

Off-label uses

• Adjunct in myocardial infarction (MI) and septic shock
• Diagnosis of coronary artery disease (echocardiography stress test, ventriculography, computed tomography)

Contraindications

• Hypersensitivity to drug
• Idiopathic hypertrophic subaortic stenosis

Precautions

Use cautiously in:
• hypertension, MI, atrial fibrillation, hypovolemia
• pregnant or breastfeeding patients
• children.

Administration

• Use infusion pump or microdrip I.V. infusion set.
• Dilute with dextrose 5% in water or normal saline solution to at least 50 ml of solution. Know that drug is incompatible with alkaline solutions, such as sodium bicarbonate injection.

Route	Onset	Peak	Duration
I.V.	1-2 min	10 min	Brief

Adverse reactions

CNS: headache

CV: hypertension, hypotension, tachycardia, premature ventricular contractions, angina, palpitations, nonspecific chest pain, phlebitis

GI: nausea, vomiting

Metabolic: hypokalemia

Respiratory: dyspnea, asthma attacks

Skin: extravasation with tissue necrosis

Other: hypersensitivity reactions including anaphylaxis

Interactions

Drug-drug. Beta-adrenergic blockers: increased alpha-adrenergic effects

Bretylium: potentiation of vasopressor activity

Cyclopropane, halothane: serious arrhythmias

Guanethidine: decreased hypotensive effects

Thyroid hormone: increased cardiovascular effects

Tricyclic antidepressants: potentiation of cardiovascular and vasopressor effects

Drug-herbs. Rue: increased inotropic potential

Patient monitoring

• As needed, correct hypovolemia before starting therapy by giving volume expanders, as prescribed.
• Monitor ECG and blood pressure continuously during administration.
• Monitor fluid intake and output.
☞ Assess electrolyte levels. Stay especially alert for hypokalemia.

Patient teaching

• Instruct patient to report anginal pain, headache, leg cramps, and shortness of breath.
• Explain need for close observation and monitoring.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and herbs mentioned above.

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adrenergic

adjective Referring to 1. Neural activation by catecholamines–eg, epinephrine, norepinephrine, dopamine. See Biogenic amines, Neurotransmitters, Sympathetic nervous system 2. Sympathetic nerve fibers that liberate epinephrine or norepinephrine into a synapse noun Any agent with adrenergic–agonist activity