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Pharm: Pre Midterm 1 > Adrenergic Agonists Continued > Flashcards

Adrenergic Agonists Continued Flashcards

1
Q

The non selective beta adrenergic agonist drug we will discuss in this class is a catecholeamine called Isoproterenol, what receptors does this drug stimulate?

A

Stimulates B1 and B2 adrenergic receptors

–action on alpha receptors is insignificant.

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2
Q

What are the cardiovascular effects of isoproterenol?

A
  • -Intense stimulation of the heart (B1)
  • -dilates arterioles of skeletal muscle (B2) = decrease in peripheral resistance
  • -may increase systolic blood pressure slightly, but it greatly decreases mean arterial and diastolic blood pressure
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3
Q

What are the pulmonary effects of isoproterenol?

A

-Bronchodilation (B2(

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4
Q

What are additional effects of isoproterenol?

A

GI Smooth Muscle relaxation
-causes less hyperglycemia than epinephrine, in part because insulin secretion is stimulated by the strong beta adrenergic activation of pancreatic islet cells

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5
Q

What is isoproterenol used for?

A

–may be used in emergencies to stimulate heart rate in patients with bradycardia or heart block

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6
Q

What are the adverse effects of isoproterenol?

A

Similar to epinephrine

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7
Q

The next drug to discuss is a beta1 selective adrenergic agonist, dobutamine, explain what that means?

A

Racemic Mixture

  • -consisting of the + and - isomers.
  • -the observed clinical result is that of a selective beta1 agonist.
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8
Q

Since dobutamine is a beta1 selective adrenergic agonist, what effect does it have?

A 
Greater inotropic (contraction) than chronotropic (heart rate) on the heart. 
--heart rate does increase modestly but contractility and cardiac output increase more.
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9
Q

What is dobutamine used for?

A

Increase cardiac output in the management of acute heart failure
Management of cardiogenic shock

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10
Q

Next drug is a beta2 selective adrenergic agonist, the first two are terbutaline and albuterol, what is the primary use of these?

A
  • -short acting beta2 agonist used primarily as bronchodilators and administered by an inhaler
  • -terbutaline is also used to reduce uterine contractions in premature labor
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11
Q

Next drug that is a beta2 selective adrenergic agonist is salmeterol and formoterol, what is the use for these drugs?

A

Long acting bronchodilators

  • -increased duration of action as a result of high lipid solubility
  • -slow onset of action after inhalation (not suitable for relief of bronchospasms)
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12
Q

In general what are some adverse effects of B2 agonists?

A

Excessive activation of b2 receptors

  • -tremor is a relatively common effect
  • -restlessness, apprehension and anxiety
  • -tachycardia when the drug is systemically administered
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13
Q

The next set of drugs is alpha 1 selective adrenergic agonists. What is the general use of these drugs?

A

—Alpha receptors in the vascular smooth muscle results in an increase in peripheral resistance and thus blood pressure is maintained or elevated

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14
Q

The main alpha 1 selective adrenergic agonist is phenylephrine, what is the use of this drug?

A

Selective alpha 1 receptor agoniset

  • -vasoconstrictor: raises both systolic and diastolic pressures
  • -it has no direct effect on the heart, but induces reflex bradycardia
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15
Q

What are some of the uses of phenylephrine?

A
  • Nasal decongestant (decrease resistance to airflow by decreasing the volume of the nasal mucosa)
  • -Mydriatic
  • -Increasing blood pressure in hypotension
  • -used to increase blood pressure and thus terminate episodes of supraventricular tachycardia
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16
Q

The next three drugs to discuss are the alpha 2 selective adrenergic agonists, the first drug is Clonidine, what is the use of this drug?

A

Partial alpha 2 agonist
–centrally acting antihypertensive agent: active alpha 2 adrenoreceptors in the cardiovascular control centers of the CNS suppressing outflow of sympathetic nervous system activity.

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17
Q

IV infusion of clonidine causes what?

A

An acute rise in blood pressure, because of activation of postsynaptic alpha 2 adrenoreceptors in vascular smooth muscle (This response is not seen orally)
–this transient vasoconstriction is followed by a more prolonged hypotensive response which results from decreased sympathetic outflow from the CNS

18
Q

What are adverse effects of clonidine?

A

Lethargy
Sedation
Xerostomia

19
Q

The second alpha 2 selective adrenergic agonist is methyldopa, what is the use of this drug?

A
  • -Antihypertensive agent
  • taken up by noradrenergic neurons and metabolized to alpha-methylnorepinephrine
  • alpha methylnorepinephrine is thought to activate central alpha 2 adrenoceptors and lower blood pressure in a manner similar to that of clonidine
  • methyldopa diminishes adrenergic outflow from the CNS, leading to reduced peripheral vascular resistance and decreased blood pressure
20
Q

Methyldopa is the drug of choice for what condition?

A

Tx of hypertension during pregnancy due to its effectiveness and safety for both mother and fetus

21
Q

What are the adverse effects of methyldopa?

A

Sedation
Menta lassitude
Impaired mental concentration
dry mouth

22
Q

The last alpha 2 selective adrenergic agonist is brimonidine, what is the use of this drug?

A

Highly selective alpha 2 agonist administered orally to lower intraocular pressure in glaucoma
–reduces aqueous humor production and increases uveoscleral outflow

23
Q

The next set of drugs are the indirect acting adrenergic agonists. The first three drugs in this category are your releasing agents, what does releasing agent mean?

A

–cause release of NE and E from the storage vesicles but blocks up take more and more from the synapse

24
Q

The first releasing agent drug is amphetamine, what does this drug do?

A
  • displaces endogenous catecholamines from storage vesicles

- -increase blood pressure by alpha 1 agonist action on vasculature as well as Beta1 stimulatory effects on the heart.

25
Q

What are the behavioral effects of amphetamine?

A

Central stimulatory action

–increased alertness, decreased fatigue, depressed appetite and insomnia

26
Q

what are the adverse effects of amphetamine?

A

Fatigue
Depression
–all following the period of central stimulation

27
Q

What is the use of amphetamine?

A

Tx of ADHD

28
Q

The next releasing agent is methylphenidate, what is the use of this drug?

A

Used to treat ADHD and narcolepsy

29
Q

The last releasing agent is tyramine, what is the use of this drug?

A

Not used clinically

  • -by product of tyrosine metabolism
  • -normally oxidized by MAO
  • -if the patient is taking MAO inhibitors it can precipitate vasopressor episodes
30
Q

The next three drugs are the uptake inhibitors. The first drug to discuss is cocaine, what are the actions of this drug?

A

Blocks reuptake of the monoamines in the presynaptic terminal

  • -blocks the dopamine transporter (DAT)
  • -high contractions block serotonin transporter (SERT) and norepinephrine transporter (NET)
  • -both these blocks lead to accumulation of the monoamines in the synaptic spaces resulting in potentiation and prolongation of their central and peripheral action
31
Q

What are the sympathetic effects of cocaine?

A

Tachycardia
Hypertension
Pupillary dilation
Peripheral vasoconstriction

32
Q

Cocaine produces an intense euphoria, what is the mechanism for this?

A

Inhibition of dopamine reuptake into the neurons of the pleasure centers of the brain

33
Q

What is the mechanism of a local anesthetic use of cocaine?

A

Blocks voltage activated sodium channels

34
Q

What is the main use for cocaine?

A

topical anesthesia of the upper respiratory tract

35
Q

The next uptake inhibitor is Atomoxetine, what is the action and use of this drug?

A

Action: selective inhibitor of the NET
Use: treatment of ADHD

36
Q

The last uptake inhibitor is Modafinil, what is the action and use of this drug?

A

Action: inhibits norepinephrine and dopamine transporters, increases synaptic concentrations of norepinephrine, dopamine, serotonin and glutamate and decreases GABA levels
use: tx of narcolepsy

37
Q

The last category of drugs in the adrenergic agonists are the mixed acting drugs, what is their mechanism of action?

A

induce the release of norepinephrine and activate adrenergic receptors

38
Q

There are two drugs for mixed acting adrenergic agonists the first is ephedrine, what is the mechanism of this drug?

A

Activates alpha and beta receptors, and releases norepinephrine from nerve ending

  • -long duration of action
  • -excellent absorption orally and does penetrate the CNS
39
Q

What are the actions of ephedrine?

A
  1. Increases systolic and diastolic blood pressure by vasoconstriction and cardiac stimulation
  2. Causes bronchodilation
  3. Produces mild stimulation of CNS: increased alertness, decreases fatigue, and prevents sleep and improves athletic performance
  4. Ephedrine + anticholinesterase = myasthenia gravis effects
40
Q

What are the uses for ephedrine?

A

1 Pressor agent, particularly during spinal anesthesia when hypotension frequently occurs

  1. Tx of allergic disorders such as bronchial asthma
  2. tx myasthenia gravis
41
Q

The second mixed acting adrenergic agonist is pseduoephedrine, what is the use of this drug?

A

Component of many nasal decongestants

–found in combination with a H1 histamine antagonist

Pharm: Pre Midterm 1 (30 decks)

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