Adrenergic Agents

Question 1

“Sympatholytics”

Answer 1

-Reduce adrenergic action

• Alpha-methyldopa (formerly Aldomet) -Outdated blood pressure med; incredibly still in use.
• Brimonidine (for glaucoma) -Alpha 2 agonist.
• Clonidine (Catapres, Kapvay) -Stimulates both alpha 2 receptors and central imidazoline receptors, but it is unknown which receptors mediate which effects.
• Dexmedetomidine (Precedex) – Alpha 2 agonist with sedative properties; IV use such as sedation for bronchoscopy.
• Guanabenz (formerly Wytensin) -Similar to clonidine.
• Guanfacine (Intuniv, Tenex) -Similar to clonidine; particularly good for ADHD; also for hypertension.
• Naphazoline, Oxymetazoline, Tetrahydrozoline, Xylometazoline

-Peripheral alpha 1 stimulant for topical vasoconstriction of nasal passages and red eyes; also central imidazoline receptor agonism like clonidine.

Question 2

Alpha Blockers

Answer 2

• Alfuzosin (Uroxatral)
• Phentolamine
• Phenoxybenzamine
• Doxazosin (Cardura)
• Tamsulosin (Flomax)
• Tolazoline
• Terazosin (Hytrin)
• Silodosin (Rapaflo)
• Prazosin (Minipress)

LOTS of other drugs have alpha blocking as a “side” effect such as phenothiazines, atypical
antipsychotics, labetalol, tricyclic antidepressants.

Question 3

Beta blockers

Answer 3

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Question 4

Direct-acting Beta agonists

Answer 4

“Sympathomimetics”

• *-Agents themselves stimulate the receptors.
• Positive cardiac inotropic and chronotropic effects; and bronchodilation**
• Albuterol
• Dobutamine
• Epinephrine (mixed alpha/beta)
• Isoproterenol
• Metaproterenol
• Norepinephrine
• Terbutaline

Question 5

Direct-acting Alpha agonists

Answer 5

“Sympathomimetic”

-Vasoconstriction (vasopressors, nasal decongestants) and mydriasis (eye exam)

• Epinephrine (mixed alpha/beta)
• Ergot alkaloids (Ergotamine, Cafergot, others)
• Metaraminol (Aramine)
• Methoxamine
• Norepinephrine (Levophed)
• Phenylephrine
• Dobutamine (very weak alpha)
• Naphazoline, Oxymetazoline, Tetrahydrozoline, Xylometazoline
• peripheral alpha1 stimulant for topical vasoconstriction of nasal passages and red eyes.
• Also central imidazoline receptor agonism like clonidine

Question 6

Indirect acting sympathomimetics

Answer 6

-Release neurotransmitters (often multiple types) from nerve terminals and/or inhibit their reuptake back into nerves.

• Amphetamines
• Cocaine
• Methylphenidate (Ritalin; Concerta)
• Propylhexedrine
• Mephentermine (Wyamine)
• Pemoline (Cylert)
• Fenfluramine (Pondimin)
• Phenmetrazine (Preludin)

Question 7

MAO inhibition

Answer 7

-Another mechanism of indirect stimulatory enhancement of neurotransmission by preventing
degradation of nor-epi,-serotonin, and dopamine.

• Isocarboxazid (Marplan) -Nonspecific MAO-A & B inhibition; antidepressant -short term use.
• Tranylcypromine (Parnate) -irreversible non selective MAOI for depression.
• Phenelzine (Nardil).
• Selegiline (Emsam transdermal patch) -irreversible MAO-B inhibitor for Parkinson’s disease.
• Pargyline (Eutonyl) -off the market.
• Linezolid (Zyvox): Antibiotic; reversible, nonselective MAO inhibitor action.
• Methylene blue: Potent, reversible MAO A inhibitor

Question 8

Mixed direct and indirect action

Answer 8

-Release Nor-epi from nerve terminal

• Dopamine

Low dose (0.5 to 2 µg/kg/min) -Stimulates dopamine receptors that enhance renal blood flow

Mid dose (2 to 20 µg/kg/min) -Directly stimulates beta1 receptors to increase strength of contraction

High dose (20 to 50 µg/kg/min) -Releases nor-epi and has vasopresssor effect.

• Ephedrine -Primarily indirect release of nor-epi; may be some direct alpha 1 stimulations also.
• Pseudoephedrine – OTC decongestant with controls on availability due to use as starting material in illegal synthesis of methamphetamine.
• Phenylpropanolamine -OTC diet aid; spikes in blood pressure pose risk of hemorrhagic stroke. Off the market in 2009 but still found as an undeclared ingredient.