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Flashcards in Adrenergics Deck (37)
0

Metaraminol

Adrenergic agonist

Alpha 1- Selective

Route: Parenteral, oral, IV, im

Clinical Use: Vasopressor (rev. hypotension NOT shock)

Long Acting Beta1, Alpha1 receptor stim

Mech: Catecholamines usually have a OH attached to benzene ring but loss of this leads to longer duration of action albeit less potent
- Due to COMT inability to metabolize efficiently

- Also has a substitution to the alpha carbon which blocks oxidation by MAO and enhances ability to displace NE in the adrenergic storage vesicles



1

Methoxamine

Adrenergic Agonist

Alpha 1 selective over Alpha 2

Clinical use: Increase blood flow or pressure

2

Phenylephrine

Adrenergic agonist

Alpha selective same for both

Route: nasal, ophthalmic, parenteral

Clinical Use: Nasal decongestant, vasopressor, local vasoconstrictor, mydriatic

Vasoconstriction (alpha 1 agonist) prevents shock,

Substituion on benzene ring to allow longer duration due to inability for COMT to act

Use to increase blood flow or pressure

Also used to decrease blood flow in attempt to reduce diffusion of local anesthetic from injection site

Elicit mydriasis

3

Alpha-methyldopa

Adrenergic Agonist

Alpha 2 selective

Prejunctional micellaneous

Receptor: alpha 2, DA2

False Transmitter

Action: Stimulate presynaptic on nerve terminals and postsynaptic alpha 2 recetors of nerve terminals,
- Inhibit NE release by terminal
- Elicit hypotension by decreasing total peripheral resistance, heart rate, cardiac output,
- Does not effect baroreceptors and rarely elicits orthostatic hypotension

SIDE EFFECTS: Sedation, Xerostomia, Anorexia, Fluid retention, vivd dreams, and CNS stimulation
- Chronic therapy may: Severe problems, hemolytic anemia, leukopenia, hepatitis, lupus-like problems

Anti-hypertensive agent able to penetrate PNS and CNS, partially replaces DOPA in synthetic pathway leading to alpha methyl NE synthesis being stored (FALSE TRANSMITTER)

4

Clonidine

Adrenergic Agonist

Alpha 2 selective (receptor agonist binds Gi)

Stimulate presynatpic on sympathetic nerve terminals and post synaptic receptors on nerve terminals in CNS

Elicit hypotension by decreasing total peripheral resistance, lowering heart rate, cardiac output, DOES NOT effect baroreceptor reflexes and rarely elicits orthostatic hypotension

5

Guanabenz

Adrenergic Agonist

Alpha 2 selective

Stimulates presynpatic on sympathetic nerve terminal and postsynaptic on CNS nerve terminals

Elicit hypotension by lowering TPR, heart rate, cardiac output, DOES NOT effect baroreceptor reflex and rarely elicits orthostatic hypotension

6

Amphetamine

Adrenergic Agonist

Mixed alpha and beta agonists

Releasing Agent

Enter nerve terminal via Amine I transport (NE displaced from storage vesicles and released into synpase

Taken in via transporter and blocks NE reuptake, reverse trasnport to release intraneuroal NE

VASOPRESSOR: stimulate alpha 1 and beta 1 receptors and act as NE releasing agents

7

Ephedrine

Adrenergic Agonist

Mixed alpha and Beta agonist

Releasing agent

Administered via: Ophthalmic, oral, parenteral, nasal

Vasopressor, mydriatic, nasal decongestant, relax bronchial smooth muscle, CNS stimulant

Stimulate most adrenoceptors

Substituions to benzene ring may lose some potency but allows drug to last longer due to inability of COMT

Substitution to alpha carbon allows enhanced ability to displace NE from adrenergic storage vesicle, blocks oxidation by MAO

Enter the nerve terminal via Amine I transport (NE gets displaced from storage vesicles and released into synapse)

Directly stimulates alpha 1 and beta 1 receptors and acts as a releasing agent

Elevates cardiac output and arterial pressure, mild stim of CNS, mild Beta 2 activity to dilate bronchial smooth muscle, nasal decongestant.

Clinical use for chronic orthostatic hypotension by achieving increased blood flow or pressure

Reduces congestion of mucous membranes by achieving decreased blood flow

Combats stress incontinence

8

Epinephrine

Adrenergic Agonist

Mixed alpha and beta agonist

Naturally occurring

Route: IV, parenteral, aerosl

Clinical use: Anaphylatic shock, relax bronchial smooth muscle, local vasoconstriction, mydriatic (glaucoma)

Relax (dilate) bronchial smooth muscle
Stimulate heart (induce heartbeat)
Emergency therapy for, Severe elevated pressure in anterior chamber of eye, anaphylatic shock, severe allergic reactions
Induce vascoconstriction (alpha 1) to restrict diffusion of drug from injection site
Applied to bleeding areas to induce vasoconstriction

Made in Adrenal Medulla

Degraded by COMT (methylation) and MAO(Deamination)

Acts on all alpha and beta receptors

Mimics sympathetic stimulation

Beta receptors more sensitive than alpha receptors to epinephrine

Released directly into venous circulation

Pheochromocytoma: tumor of adrenal medulla, characterized by very elevated release of epinephrine into venous circulation
- Severe tachycardia, hypertension, headaches, increased sweating

Very potent vasoconstrictor and cardiac stimulant, systolic BP increased due to B1 effects on heart and alpha 1 receptor mediated vasoconstriction in vascular beds
- Vasodilation in skeletal muscle due to B2 activity to decrease TPR

Favored method of treatment for anaphylaxis


9

Norepinephrine

Adrenergic Agonist

Alpha and Beta selective (not much Beta 2 action)

Inhibit Amine I transport increase concentration of this within the synapse and mimic responses of sympathetic nerve stimulation

Administered via IV infusion only

Clinical Use: Vasopressor (shock)

Vasoconstriction (alpha 1) and cardiac output (beta 1)

Primary neurotransmitter of adrenergic nerves

Degraded by methylation from COMT and deamination from MAO

Transported into nerve terminals via vesicular monoamine transporter (VMAT)

Released via exocytosis triggered by Ca2+

Recycled back into the nerve terminal via Amine I transport (NET)

Peripheral resistance and diastolic/systolic BP increased
- Little effect on Beta 2 receptors

Can reduce diffusion of local anesthetics from injection site as well



10

Dobutamine

Adrenergic Agonist

Beta 1 selective

IV infusion (short acting)

Force cardiac contraction, Increase Cardiac output (congestive heart failure)

Substitutions to amino group to increase Beta activity

Increase lipolysis as well

Receptor agonist binds Gs

Increased blood flow or pressure in case of CARDIOGENIC SHOCK following MI

Rescuing cardiac function from Heart Failure

11

Isoproterenol

Adrenergic Agonist

B non-selective

Distribution: aerosol, parenteral

Clinical action: relax bronchial smooth muscle, cardiac stimulant (A-V block) (asthma)

Primary use for stimulation of B2 adrenoceptors relaxation of bronhcial smooth muscle,

Can be used for cardiac stimulation (Beta 1)

Substitution to amino group to increase beta activity

Very potent Beta agonist with very little alpha activity
- Potent vasodilator, significant increase in cardiac output with beta 1 receptor activity
- Decreased MAP by vasodilation due to Beta 2 receptor activity

12

Albuterol

Adrenergic Agonist

Beta 2 selective

Skeletal muscle vasodilation, smooth muscle relaxation, decreased intraocular pressure

13

Metaproterenol

Adrenergic agonist

Beta 2 selective

Smooth muscle relaxant, vasodilate skeletal muscle

14

Terbutaline

Adrenergic Agonist

Beta 2 selective

RElax smooth muscle

Routes: parenteral, oral aerosol

Substitute amino group to allow increased Beta activity

Relax Pregnant Uterus

15

Bromocriptine

Adrenergic Agonist

Dopamine agonist

Autoreceptor: DA2, alpha 2

Primarily used as an anti-parkinson agent w/CNS activities

D2 receptors on post synpatic effector sites in the CNS are not INVOLVED in feedback inhibition

16

Dopamine

Adrenergic agonist

Dopamine receptor agonist

Administered: IV infusion

Major clinical usage: Vasopressor (shock)

Only used by IV infusion for shock therapy
Vasoconstriction (alpha 1)
Increase cardiac output (beta 1)
Dilate renal blood vessels (DA1)

Released by postganglionic sympathetic nerves of renal and splanchnic vascular smooth muscle

D1 receptor: vasodilation (renal, mesenteric)
D2 receptor: binds Gi, presynpatic nerve terminals (provide negative feedback to decrease NT release from terminals

17

Fenoldopam

Adrenergic Agonist

Dopamine receptor selective (D1 selective)
- D1: receptor agonist binds Gs, vasodilation (renal, mesenteric)

18

Doxazosin

Adrenergic Antagonist

Alpha 1 selective

Inhibit constriction/contraction resulting in vasodilation and lower MAP
- Efficaous in relieving urinary symptoms (urinary obstruction, Benign prostatic hyperplasia)

19

Prazosin

Adrenergic Antagonist

Alpha 1 receptor selective

Antihypertensive

Blocks alpha 1 receptors and results in EPINEPHRINE REVERSAL

Competitive reversible antagonist

Advance for therapeutic application

Exhibit little orno tachycardia due to alpha 1 selectivity
NO inhibition of Beta 1
Good duratino of action 12 hours

20

Tamsulosin

Adrenergic Antagonist

Alpha 1 selective

Effective at relieving urinary symptoms due to BPH

21

Terazosin

Adrenergic antagonist

Alpha 1 selective

Inhibit constriction/contraction resulting in vasodilation and lower MAP

Helps relieve urinary obstruction due to BPH

22

Phenoxybenzamine

Adrenergic antagonist

Alpha non-selective

Amine I Transport (NET=norepinephrine transport) INHIBITOR

Alpha 1 activity greater than Alpha 2

NONCOMPETITIVE antagonist of alpha 1 and alpha 2 receptors and INHIBITS NET by forming cyclic derivative

Duration: 24 hours

Orally or IV

Induces hypotension, tachycardia: DUE to reflex activation of adrenergic nervous system (due to lowered MAP)

- NO inhibition of Beta 1 receptors in heart

Pheochromocytoma: used for management of hypertension preoperatively
- Also in cases where inoperative/metastatic tumors present

- ADJUNCT drug in therapy for SEVERE hypertension

23

Phentolamine

Adrenergic antagonist

Alpha non-selective

Used in DIAGNOSTIC: Pheochromocytoma (Regitine Test)

Alpha 1= Alpha 2

COMPETITIVE antagonist

Inhibits alpha 1 and alpha 2 with equal efficacy, THERAPEUTIC ABILITY due to alpha 1 inhibition

Antagonism of alpha 1 receptors leads to vasodilation
Alpha 2 antagonism leads to INCREASED NE release (since B1 not blocked get high cardiac output and tachycardia)

-DIRTY DRUG: Reacts with other receptors (muscarinic, histamine)

Pheochromocytoma: Same effects as Phenoxybenzamine

24

Labetalol

Adrenergic Antagonist

Mixed alpha and beta antagonist

Has more Beta activity than alpha, alpha 1 more than alpha 2

25

Atenolol

Adrenergic antagonist

Beta 1 selective

Used to treat hypertension (inhibit cardiac output and dilation/relaxation) inhibit cardiac output

Duration: 6-9 hours
Used with great caution for patients with asthma or COPD

Less CNS side effects due to diminished ability to cross BBB

26

Betaxolol

Adrenergic Antagonist

Beta 1 selective

Used to inhibit cardiac output

Duration of Action: 14-22 hours

Clinical use: Glaucoma

27

Metoprolol

Adrenergic Antagonist

Beta 1 selective

Antihypertensive

Inhibit cardiac output

Duration of action: 3-4 hours
- Antihypertensive, angina pectoris

EFFECTIVE PROPHYLACTIC agent to prevent recurrence of MYOCARDIAL INFARCTION, help with long term survival

Side Effects: ATAXIA, DIZZINESS, major problems with initial therapy

28

Nadolol

Adrenergic Antagonist

Beta non-selective

Duration of action 14-24 hours
- Beta 2 activity may inhibit dilation of bronchioles, significant for patients with ASTHMA

ANTIHYPERTENSIVE

Produces fewer CNS effects due to diminished ability to cross BBB

29

Pindolol

Adrenergic Antagonist

Beta non selective

Antihypertensive

Duration of action: 3-4 hours

30

Propranolol

Adrenergic Antagonist

Beta non selective

ANTIHYPERTENSIVE, ANTI-ARRHYTHMIC, ANGINA PECTORIS, MIGRAINE HEADACHE

Duration of action: 3-6 hours

May lead to dilation of bronchioles which will be tough on patients with asthma

Adverse Effect: Ataxia and Dizziness

Long term use following myocardial infarction prolongs survival (suppress arrhythmias)

31

Timolol

Adrenergic Antagonist

Beta non selective

Used for: LOWER INTRAOCULAR PRESSURE, ANTIHYPERTENSIVE, ANGINA PECTORIS

Long term use is effective for prolonged survival in MI patients

Duration of action: 4-5 hours

32

Guanethidine

Miscellaneous Pre-Junctional

Nerve Terminal Membrane Stabilizer

Depletes NE

Oral Route: Antihypertensive therapy for most severe elevated Arterial Pressures

Hypotensive activity due to eliciting reduced NE release

Agents that inhibit transport (cocaine), tricyclic antidepressants will antagonize (inhibit) desired hypotensive effect

Stabilizes neuronal membranes, interfering with exocytosis

Chronic administration is accompanied by depleting NE within synaptic vesicles

Minimal effects with other biogenic amines (EPI, DA)

Minimal adverse effects in CNS since does not cross BBB

33

Reserpine

Miscellaneous Pre-Junctional

Norepinephrine Depletion

Depletes EPI, NE, DA, SEROTONIN in both CNS and PNS by blocking transport into storage vesicles

Very Potent, ORALLY EFFECTIVE, Long Duration of Action

Adverse effects are in CNS (sedation, depression, parkinsonian symptoms)K


Increased GI motility leads to ulcers

34

Cocaine

Inhibit Amine I Transport (NET) (NE rises in synapse)

Achieves decreased blood flow (hemostasis during surgery)

35

DMI (desmethylimipramine)

Amine I Transport Inhibitor

Tricyclic antidepressant

36

Tyramine

Phenylethylamine derivative that enters nerve terminal via Amine I transport

Found in cheeses, dangerous for individuals on MAO, combination of lower synaptic NE metabolism with increased NE release from this agent

Elevates arterial pressure