- D1 selective receptor agonist at low doses - At medium doses also agonist at b1 and b2 adrenergic receptors - At high doses also agonist at a1 and a2 adrenergic receptors

2. Adrenergics Flashcards by John Halerz

Sympathomimetics - Available Drugs

Epinephrine
Norepinephrine
Isoproterenol
Dopamine
Dobutamine
Phenylephrine
Metaproterenol
Albuterol
Salmeterol
Terbutaline
Ritodrine

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Epinephrine - MOA

Agonist at a1, a2, b1, and b2 adrenergic receptors.

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Epinephrine - Clinical Use

Anaphylaxis, glaucoma (open angle), asthma, hypotension

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Norepinephrine - MOA

Agonist at a1, a2, and b1 adrenergic receptors.

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Norepinephrine - Clinical Use

Hypotension (but decreases renal perfusion)

Increase systolic BP due to effects on b1 increase on chronotropy and ionotropy of heart.
Increase diastolic BP due to effects on a1 causing vasoconstriction
Large BP increase will cause reflex bradycardia

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Isoproterenol - MOA

Beta selective adrenergic agonist (b1 and b2)

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Isoproterenol - Clinical Use

AV block
Bradycardia
Transient increase systolic BP due to effects on b1 increase on chronotropy and ionotropy of heart. Overcome by vasodilatory effects and will drop slightly
Decrease diastolic BP due to effects on b2 causing vasodilation
Large BP decrease will cause reflex tachycardia

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Dopamine - MOA

D1 selective receptor agonist at low doses
At medium doses also agonist at b1 and b2 adrenergic receptors
At high doses also agonist at a1 and a2 adrenergic receptors

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Dopamine - Clinical Use

At low doses to increase renal perfusion in shock [D1 receptor]
At medium doses for heart failure –> ionotropic and chronotropic [b1 and b1 receptors]

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Dobutamine - MOA

Agonist at a1, a2, and b1 adrenergic receptors.

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Dobutamine - Clinical Use

Heart failure, cardiac stress testing

- ionotropic and chronotropic

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Phenylephrine - MOA

Alpha selective adrenergic agonist (a1 and a2)

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Phenylephrine - Clinical Use

Hypotension (vasoconstrictor)
Ocular procedures (mydriatic)
Rhinitis (decongestant)

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Metaproterenol - MOA

Beta selective adrenergic agonist (b1 and b2)

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Metaproterenol - Clinical Use

Acute asthma

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Albuterol - MOA

Beta selective adrenergic agonist (b1 and b2)

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Albuterol - Clinical Use

Acute asthma

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Salmeterol - MOA

Beta selective adrenergic agonist (b1 and b2)

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Salmeterol - Clinical Use

Long term treatment of asthma

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Terbutaline - MOA

Beta selective adrenergic agonist (b1 and b2)

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Terbutaline - Clinical Use

Reduce premature uterine contraction

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Ritodrine - MOA

b2 selective adrenergic agonist

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Ritodrine - Clinical Use

Reduce premature uterine contractions

Indirect Sympathomimetics - Available Drugs

Amphetamine
Ephedrine
Cocaine

Amphetamine - MOA

Indirect adrenergic agonist --> Causes release of stored catecholamines

Amphetamine - Clinical Use

Narcolepsy, obesity, ADD

Ephedrine - MOA

Indirect adrenergic agonist --> Causes release of stored catecholamines

Ephedrine - Clinical Use

Nasal decongestion, urinary incontinence, hypotension

Cocaine - MOA

Indirect adrenergic agonist --> Prevents reuptake of catecholamines

Cocaine - Clinical Use

Causes vasoconstriction and local anesthesia

Sympathoplegics - Available Drugs

Clonidine | a-Methyldopa

Sympathoplegics - MOA

Centrally acting a2-agonists --> decrease central adrenergic outflow (Clonidine, a-Methyldopa)

Sympathoplegics - Clinical Use

Hypertension, especially with renal disease (does not decrease blood flow to kidney. (Clonidine, a-Methyldopa)

Non-selective alpha Blockers - Available Drugs

Phenoxybenzamine (irreversible) | Phentolamine (reversible)

Phenoxybenzamine - MOA

Irreversible block of alpha adrenergic receptors

Phenoxybenzamine - Clinical Use

Pheochromocytoma, use before removal of the tumor

Phenoxybenzamine - Toxicities

Orthostatic hypotension, reflex tachycardia

Phentolamine - MOA

Reversible block of alpha adrenergic receptors

Phentolamine - Clinical Use

Give to patients on MAOi's who eat tyramine containing foods (fava beans, aged cheese)

Phentolamine - Toxicities

Orthostatic hypotension, reflex tachycardia

a1 Selective Blockers - Available Drugs

Prazosin, Terazosin, Doxazosin "-zosin"

a1 Selective Blockers - MOA

Selective blockade of the a1 adrenergic receptor. | Prazosin, Terazosin, Doxazosin

a1 Selective Blockers - Clinical Use

- Hypertension - Urinary retention in BPH (Prazosin, Terazosin, Doxazosin)

a1 Selective Blockers - Toxicities

- 1st dose orthostatic hypotension - dizziness, headache (Prazosin, Terazosin, Doxazosin)

a2 Selective Blockers - Available Drugs

Mirtazapine

Mirtazapine - MOA

Selective blockade of the a2 adrenergic receptor.

Mirtazapine - Clinical Use

Depression

Mirtazapine - Toxicities

Sedation, increased cholesterol, increased appetite

Effects of alpha Blockade on Epinephrine vs. Phenylephrine

Epinephrine has both alpha and beta effects. When combined with an alpha blocker the beta effects will win and the net result will be a depressor effect below baseline BP. Phenylephrine has only alpha effects. When combined with an alpha blocker it has little or no effects and the net result will be a reversal of the pressor effect back to baseline BP.

b1 Selective Blockers - Available Drugs

Acebutelol, Betaxolol, Esmolol, Atenolol, Metoprolol "A BEAM through the heart"

Non-selective beta Blockers - Available Drugs

Propranolol, Timolol, Nadolol, Pindolol "Please Try Not (b)eing Picky"

Partial beta Agonists - Available Drugs

Pindolol, Acebutolol "Partial Agonist - Pindolol, Acebutolol --> PAPA"

Non-selective alpha and beta Antagonists - Available Drugs

Carvedilol, Labetalol

Beta Blockers - Clinical Use

- Hypertension - decrease CO, decrease renin secretion (beta blockade on juxtaglomerular cells) - Angina - Decrease HR and contractility resulting in decrease O2 consumption - MI - Reduce mortality - Supraventricular tachycardia (SVT) - Decrease AV conduction velocity (class II antiarrhythmic) [Propranolol and Esmolol] - CHF - Slows progression of chronic failure - decrease cardiac dilation - Glaucoma - Decrease secretion of aqueous humor [Timolol]

Beta Blockers - Toxicities

- Impotence, exacerbation of asthma, bradycardia, AV block, CHF, sedation, sleep alteration. - Use with caution in diabetics - can decrease body's response to hypoglycemia

b1 Selective Blockers - Advantage Over Other beta Blockers

Cardiac specific - Better to use in patients with comorbid pulmonary disease - Less chance of exacerbation due to b2 effects.

Partial beta Agonists - Advantage Over Other beta Blockers

Will have less of the negative cardiovascular side effects (ie less bradycardia)