Adrenergics Flashcards Flashcards by Maxine B

A group of non-selective agents grouped according to mode of action. Directly interacts with and activates on one or more of the adrenoreceptors;

Direct Acting Agents

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Endogenous drug mainly used for anaphylactic shock + bronchodilator.

Epinephrine

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Give the 4 catecholamines and classify them as endogenous and exogenous.

Endo - Epi, Norepi, Dop; Exo: Isoproterenol

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Selective a1 agonist that is used as oral/nasal decongestant, vasopressor, mydriatic and hemostatic agent.

Phenylephrine

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SHORT ACTING Selective B2 agonist used for asthma/COPD

Salbutamol, Albuterol, Terbutaline

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Selective B3 agonist used for overreactive bladder

Mirabegron

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Agents that depend on the ability to increase the endogenous catcholamines endings to stimulate adrenergic receptor by 2 mechanisms: release/displace stored NE from adrenergic receptors or decrease clearance of released NE.

Indirect Acting Agents

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Drug that displace/release stored NE from adrenergic nerve endings. Used for ADHD and narcolepsy, off-label indicated for obesity.

Amphetamine

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Drug that displace/release stored NE from adrenergic nerve endings. Still used for ADHD and narcolepsy

Methylphenidate

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Indirect-acting drugs withdrawn due to hepatic failure. Drug that displace/release stored NE from adrenergic nerve endings

Pemoline

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Indirect-acting drug that displace/release stored NE from adrenergic nerve endings for narcolepsy.

Modafinil

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Indirect-acting substance that displace/release stored NE from adrenergic nerve endings (NOT a drug) and found from aged cheese, anchovies, pickled herring

Tryamine

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Indirect-acting drug that decrease clearance of released norepinephrine (catecholamine reuptake inhibitors) w/c function for serotonin and dopamine release. Also to manage bed-wetting problems.

Tricyclic antidepressants

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Indirect-acting drug that decrease clearance of released norepinephrine (catecholamine reuptake inhibitors) w/c treats ADHD.

Atomexotine, Reboxetine

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Indirect-acting drug that decrease clearance of released norepinephrine (catecholamine reuptake inhibitors) that functions as antidepressants and for fibromyalgia.

Duloxetine

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Indirect-acting drug that decrease clearance of released norepinephrine (catecholamine reuptake inhibitors) which treats fibromyalgia.

Milnacipran

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Indirect-acting drugs that block metabolizing enzymes (decrease clearance of NE) which function as MOA inhibitor

Pargyline

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Indirect-acting drugs that block metabolizing enzymes (decrease clearance of NE) which function as COMT inhibitor.

Entacapone

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Which group of drugs ndirectly release NE and also directly activate receptors

Mixed-acting sympathomimetics

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A mixed acting drug which can activate both a and b receptors used for oral/nasal decongestant. Indirectly releases NE. Can also traverse BBB.

Ephedrine

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A mixed acting drug which is also an oral/nasal decongestant BUT is now REGULATED due to shabu use.

Pseudoephedrine

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A mixed acting drug which can be an oral/nasal decongestant and for weight loss in high doses BUT can cause hemorrhagic stroke.

Phenylpropanolamine (Regulated dose: 12.5-30 mg)

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A mixed acting drug which can prevent hypotension after administering spinal anesthesia.

Mephentermine

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A mixed acting drug which are for hypotensive states.

Metaraminol

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Drug most potent in B receptor activation.

Isoproterenol / Isoprenaline

Non selective receptor agonists. Epinephrine actiaves ____ and norepinephrine activates ____.

all; a and b1

Selective a1 agonist treatment for orthostatic hypotension.

Midodrine

Selective a1 agonist. Imidazole-derived short-acting topical nasal decongestants

Naphazoline, Tetrahydrozoline

Selective a1 agonist. Imidazole-derived long-acting topical nasal decongestants

Oxymetazoline, Xylometazoline

Selective/centrally acting a2 agonist for wide-angle glaucoma.

Apraclonidine, Brimonidine

Centrally acting a2 agonists (4 drugs)

Clonidine, Methyldopa, Guanfacine, Guanabenz

Selective/centrally acting a2 agonist for muscle spasticity and spinal cord disorders.

Tizanidine

Selective B1 agonist but can also activate a receptors.

Dobutamine

Partial B1 agonist.

Pranelterol

Selective B2 agonist NOT for ASTHMA but used to increase athlete's physical performance.

Clenbuterol

LONG ACTING Selective B2 agonist used as bronchodilators.

Salmeterol, Formoterol, Bambuterol, Arfomoterol

LULTRA LONG ACTING Selective B2 agonist used for asthma/COPD

Indacaterol

Selective B2 agonist used to prevent uterine contraction, arrest premature labor but NOT USED TODAY because of ADR

Ritodrine

Selective B2 agonist to stimulate vascular smooth muscles; causes vasodilation, increas e blood flow useful in peripheral vasospastic or vascular diseases;

Isoxsuprine

Intermediate acting B2 agonist

Bitolterol, Procaterol

Dopamine receptor for treatment of shock due to activation of D1 receptors in mesenteric and renal blood vessels, which causes relaxation of vascular smooth muscles and vasodilation and increased perfusion to vital organs.

Dopamine, Dopexamine

D1 receptor used in IV treatment of severe hypotension and Parkinson’s disease

Fenoldopam

Preferred route of administration for catecholamines (3 routes)

Parenteral, Inhalation, Topical. Can't be oral because it is polar and rapidly inactivated by intestinal mucosa and liver (short duration of aciton)

NET can be inhibited by what drug?

Tricyclic antidepressants

Catecholamines can be degraded by MAO and COMT and converted to ____ or partly conjugated to ______ which is excreted in the urine.

VMA, sulfate or glucuronide derivatives

Found in the mitchondria, at nerve endings, liver, intestinal epith and can terminate transmitter action in the CNS. Can be inhibited by Pargyline.

MOA

Vascular smooth muscle contain both of these receptors.

a1 for vasoconstriction, b2 for vasodilation to increase blood flow

Renin release is activated by what receptor.

B-islet cells secrete insulin via ____ and inhibited via ____.

B2, a2

a-islet cells secrete glucagon via ____.

B receptors

2 Groups of drugs that can traverse CNS and induce wakefulness, excitement, irritability

Amphetamine, Ephedrine

If a2 is located in the sympathetic nerve endings, what happens?

negative feedback since a2 has autoreceptors

If as is located in the cholinergic nerve endings, what do they do?

inhibit release of NE even if cholinergic nerve endings release Ach, these are called heteroreceptors

Selectivity is dose-related, not absolute and is lost at higher concentrations. (T/F)

TRUE

Dobutamine only actiaves ___ (B1/B2) in high doses.

B2 (mainly B1-selective at normal doses)

decrease in response to the same dose of the drug given for a period of time

Tolerance

acute form of tolerance that develops rapidly given a few successive doses at set intervals; associated with indirectly acting sympathomimetic agents

Tachypylaxis

Refractoriness means treatment success (T/F)

FALSE (treatment failure)

Mechanism of desensitization that down-regulates; after administration of a drug for a long period of time, the receptors become less responsive to the agonist

Homologous (phosphorylation of GPCR kinase, affinity for arrestin, interact with clatrhin and clathrin adaptor AP2, endocytosis of receptor)

Process by which desensitization of one receptor by its agonists results in desensitization of another receptor that has not been directly activated by the agonist in question

heterologous

SAR: Substitutions produces different affinities for receptors and determines PK, PD, and bioavailability. (T/F)

FALSE. No PD, only PK and bio

Catecholamines have an OH on the 3rd and 4th position of benzene ring which means it has a maximal a and B activity. (T/F)

TRUE

Substitutions on benzene ring (no OH at C3) decreases potency, less activity, but increases bioavailability, prolong duration of action, and can pass BBB (T/F)

TRUE (Epinephrine is an example)

Two OH groups are absent in this drug which makes it more orally available, more potent in traversing CNS, and easily penetrates BBB, leading to longer duration of action.

Ephedrine

Substitution on amino group by a (larger/smaller) alkyl increases and decreases (a/B) receptor activity, respectively.

larger, B, a

Substitution (OH) on ____ (alpha carbon/B carbon) blocks oxidation (degradation) of MAO, giving rise to prolonged duration of action. This increases ability to displace catecholamines from storage sites.

alpha

Substitution (OH) on ____ (alpha carbon/B carbon) leads to increase in storage of sympathomimeticamines in neural vesicles .

Beta (EXCEPT DOPAMINE because it doesn't have an OH group but can still be stored)

Small dose (.1 mcg/kg) of epinephrine activates best which receptor?

B2 (vasodilates, decreases PVR, dec diastolic BP)

Large dose of epinephrine affects both of these receptors, producing a biphasic response. Which are these receptors?

a1 for vasoconstriction, increased PVR (transient) then when it wanes, activates b2 for vasodilation, decreases PVR, dec diastolic BP. alpha receptor blocker reverses epinephrine's transient effects, which makes B2's effect unopposed.

Biphasic response is not seen in norepinehprine (T/F)

TRUE

Increase in SBP and DBP (total blood pressure) due to epinephrine can provoke reflex bradycardia. (T/F)

FALSE

Rapid IV dose can provoke reflex bradycardia because of which receptors?

a1 for vasoconstriction, increased PVR, increased DBP; b1 for increase in CO

Slow IV or SubQ injection cannot produce reflex bradycardia because dose being administered to which 2 receptors is not high?

B1 for increase in CO; B2 for vasodilation, decrease PVR, dec DBP

Slightly higher rates of IV infusion can induce compensatory reflex. Total PVR DEPENDS on the dose and net effect on which 2 receptors?

a1 for vasocon, inc PVR, inc DBP; b2 for dec PVR, dec DBP (b1 can also be affected for increased CO)

Epinephrine causes hyperglycemia and hyperlactacidemia via what 2 receptors?

B2 for inc glycogenolysis, inc glucose, inc B-islet insulin secretion; then a2 can counteract and inhibit insulin release

Epinephrine causes hyperlipidemia via what receptor?

B receptors induce lipolysis

Epinephrine causes bronchodilation via what receptor?

B2; a receptor inhibits bronchial secretion and congestion

Epinephrine causes constipation via what receptors?

a2, b2 decreaes motility; a1 constricts ileocecal and pyloric sphincters

Epinephrine can delay premature labor via what receptor?

b2 decreases uterine contraction (a1 counteracts, promote contraction)

Epinephrine causes urinary hesitancy (retention) via what receptors?

b2 relaxes detrusor ms; a1 constricts sphincter, contraction of trigone

Epinephrine causes mydriasis via what receptors?

a1 contracts radial muscle of iris, can decrease IOP for wide angle glaucoma

In CAD, Sympathomimetic drugs are avoided because activation of this receptor can aggrave CAD.

B1 increaes inotropy, chronotropy, dromotropy, inc CO

In arteriosclerosis, ____ receptor activation can promote increased PVR and BP.

Epinephrine is what kind of antagonist?

Physiologic, can act in the same system with opposing effects (a1-vasocon, b2-vasodilate; b1 increase CO)

Drug of choise for anaphylaxis is ____ and given in 1:1000 (1mg/mL) aqueous solution, 0.3-0.5mg subcutaneous (can be given after 5-15 minutes).

Epinephrine