Alpha and Beta Adrenergics Flashcards by Julie Peceny

Direct acting adrenergic receptor agonists

Dopamine (Intropin)
Norepinephrine (Levophed)
Epinephrine (Adrenalin)

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alpha 2 receptors mainly mediate

cardio control center in the CNS (brain stem)

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Beta 1 receptors mainly deal with what

heart (cardiac muscle), control renin release in the kidney

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Beta 2 receptors mainly deal with what

smooth muscle vasculature, skeletal muscle blood vessels, bronchiole smooth muscle and uterine smooth muscle

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direct acting alpha1 receptor agonists mediate

vasoconstriction and can also mediate pupil dilation (radial muscle under alpha1 control)

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alpha 1 receptor agonists

Phenylephrine (Neosynephrine)
Methoxamine (Vasoxyl)
Oxymetazoline (Visine)

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alpha 2 receptor agonists

Clonidine (Catapres)
Methyldopa (Aldomet)
Guanabenz (Wytensin)
Guanfacine (Texex)
Tizanidine (Zanaflex)

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Non-selective beta receptor agonist

Isoproterenol (Isuprel)

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Beta1-selective receptor agonists

Dobutamine (Dobutrex)

Dopamine (Inotropin)

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Beta2-selective receptor agonists

Terbutaline (Brethine, Bricanyl)
Metaproterenol (Metaprel, Alupent)
Albuterol (Proventil, Ventolin)
Salmeterol (Serevent)
Ritodrine (Yutopar)

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What is the EC50?

drug concentration at which 50% of the receptors are activated

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cardiovascular effects of alpha1 agonists

vasoconstriction, which increases blood pressure

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cardiovascular effects of beta1 agonists

expect increased heart rate, but baroreceptors increase vagal tone, which slows heart rate

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cardiovascular effects of beta2 agonists

vasodilation, which decreases the blood pressure (drop in bp may also trigger baroreceptor reflex to increase heart rate)

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effects of norepinephrine on heart rate

net effect = decreased heart rate
alpha1 agonist increases blood pressure but increases heart rate from beta1 agonist increases vagal tone, which decreases heart rate

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effects of epinephrine on heart rate

observe expected increase in heart rate with beta1

alpha1 and beta2 essentially cancel out effects on blood pressure ( no change in BP)

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effects of isoproterenol on heart rate

increase in heart rate
beta2 - decrease in blood pressure, increase heart rate
beta1 - increase in heart rate

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What type of agonist is l-Norephinephrine (Levophed)

potent alpha and beta1 receptor agonist

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What is l-Norephinephrine used for?

used as a pressor, drives blood pressure up, stimulates heart (slow/no change in heart rate)

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What type of agonist is Ephinephrine (Adrenalin)?

potent alpha, beta1, and beta2 receptor agonist

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What is Ephinephrine (Adrenalin) used for?

anaphylaxis, glaucoma, in combination with local anesthetics (vasoconstriction to keep anesthetic in area longer)

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What type of agonist is Phenylephrine (Neo-Synephrine)?

potent alpha1 receptor agonist

very effective orally (not a substrate for COMT)

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What is Phenylephrine used for?

nasal decongestant, mydriasis without cycloplegia (paralysis of ciliary muscle in eye), glaucoma, pressor (raises BP)

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What type of agonist is Naphazoline (Privine)

Study These Flashcards

partial agonist at alpha receptors

What type of agonist is Tetrahydrozoline (Visine)

partial agonist at alpha receptors

What type of agonist is Oxymetazoline (Afrin, Visine)

partial agonist at alpha receptors

alpha1 agonist side effects

changes in blood pressure (increase) | CNS stimulation at increased doses

What are Nephazoline, Tetrahydrozoline, and Oxymetazoline used for?

nasal and ophthalmic decongestants | OTC in nasal sprays

What is the concern with Nephazoline, Tetrahydrozoline, and Oxymetazoline?

Tachyphylaxis/Desensitization: causes alpha1 receptors to not respond as well long-term, can cause rebound congestion

What type of agonist is Clonidine (Catapres)?

selective alpha2 receptor agonist

Clinical effects of Clonidine

clinical effect linked to activation of alpha2 receptors in the nucleus of the solitary tract (cardiovascular center)

Uses of Clonidine

very effective anti-hypertensive agent, opiate withdrawal

How do alpha2 adrenergic agonists reduce blood pressure

by reducing sympathetic output from the brain

cardiovascular effects from the decreased sympathetic tone caused by alpha-adrenergic agonists

decreased heart rate, decreased contractility, decreased renin release, decreased vasoconstriction

Guanabenz (Wytensin) and Guanfacine (Tenex, Intuiv)

variants of Clonidine, used in hypertension and ADHD (guanfacine)

What is Methyldopa (Aldomet)?

a prodrug metabolized to active alpha2 receptor agonist, (1R, 2S)-alpha-methylnorepinephrine

Where does Methyldopa act?

acts at CNS alpha2 receptors to decrease sympathetic outflow

What is Methyldopa used for?

hypertension

Apraclonidine (Iopidine)

alpha2 receptor agonist | used in glaucoma

Tizanidine (Zanaflex)

alpha2 receptor agonist | used for muscle spasticity (alpha2 receptors in the spinal cord activate the reflex arc)

Adverse effects of alpha2-adrenergic receptor agonists

sedation, sodium and water retention, dry mouth, withdrawal symptoms

What kind of agonist is Isoproterenol (Isuprel)?

non-selective beta receptor agonist

What is isoproterenol used for?

asthma, chronic obstructive pulmonary disease, cardiostimulant

What type of agonists are Metaproterenol and Terbutaline?

selective beta2 receptor agonists | resorcinol derivatives

What are Metaproterenol and Terbutaline used for?

asthma, COPD; Terbutaline used as tocolytic (prevents premature labor)

What kind of effect can you observe only at high doses of Metaproterenol and Terbutaline?

cardiac effects

What type of agonist is Albuterol (Ventolin, Proventil) and Levalbuterol (Xopenex)?

selective beta2 receptor agonists

What is Albuterol/Levalbuterol used for?

short acting bronchodilation; asthma and COPD

What type of agonist is Salmeterol and Formoterol?

selective beta2 receptor agonist

How is Salmeterol/Formoterol different from albuterol?

Salmeterol/Formoterol are a long acting agents (not recommended for acute treatment of asthma symptoms)

How is Salmeterol/Formoterol used?

long acting bronchodilation; asthma and COPD

Different between Salmeterol and Formoterol?

onset of action: Salmeterol - 10-20 min Formoterol -

What is the net effect of Dobutamine (Dobutrex)?

positive inotropic effect on heart with little chronotropic effect (increases force of contraction with little increase in heart rate)

What is Dobutamine used for?

acute heart failure, shock

Where do indirect-acting sympathomimetrics act?

act at a target other than the receptor - causes a buildup of neurotransmitter

Name some indirect-acting sympathomimetics

amphetamine, pseudoephedrine, ephedrine, phenylpropanolamine, tyramine

How do indirect-acting sympathomimetics work?

promote release of NE via reverse action of plasma membrane transporter

Clinical uses of indirect acting sympathomimetics

amphetamines: ADHD, narcolepsy, anorexiant others: nasal decongestants

Alpha and Beta Adrenergics Flashcards

(58 cards)