Chapter 18 - Adrenergic Agonists and Adrenergic Blockers

Question 1

Drugs that stimulate the sympathetic nervous system by mimicking the sympathetic neurotransmitters norepinephrine and epinephrine.

Answer 1

Adrenergics, Adrenergic Agonists, or Sympathomimetics.

Question 2

Where are adrenergic receptor sites located at?

Answer 2

In the effector muscles, such as the heart, bronchiole walls, GI tract, urinary bladder, and ciliary muscle of the eye.

Question 3

What happens when the Alpha1-adrenergic receptors are stimulated?

Answer 3

Increases force of heart contraction;
Vasoconstriction increase blood pressure;
Mydriasis (dilation of pupils);
Decreases secretion in salivary glands;
Increases urinary bladder relaxation and urinary sphincter contraction

Question 4

Where are the Alpha1-adrenergic receptors located?

Answer 4

In blood vessels, eye, bladder, and prostate.

Question 5

What happens when there is too much stimulation in the Alpha1-adrenergic receptors?

Answer 5

Blood flow is decreased to the vital organs.

Question 6

What happens when the Alpha2 receptors are stimulated?

Answer 6

Inhibit release of norepinephrine;
Dilates blood vessels;
Produces hypotension;
Decreases GI motility and tone.

Question 7

Where are the Alpha2 receptors located?

Answer 7

Postganglionic sympathetic nerve endings

Question 8

What happens when the Beta1 receptors are stimulated?

Answer 8

Increases the heart rate and force of contraction;

Increases renin secretion, which increases blood pressure.

Question 9

Where are the Beta1 receptors located?

Answer 9

In the kidney, but primarily in the heart.

Question 10

What happens when the Beta2 receptors are stimulated?

Answer 10

Dilates bronchioles;
Promotes GI and uterine relaxation;
Promotes increase in blood sugar through glycogenesis in liver;
Increases blood flow in skeletal muscles.

Question 11

Where are the Beta2 receptors located?

Answer 11

Found mostly in the smooth muscles of the lung and GI tract, the liver, and the uterine muscle.

Question 12

What happens when the dopaminergic receptor is stimulated?

Answer 12

The vessels dilate;

Blood flow increases.

Question 13

Where are the dopaminergic receptors located?

Answer 13

Renal, Mesentric, Coronary, and Cerebral arteries.

Question 14

What is the only hormone that can activate the dopaminergic receptor?

Answer 14

Dopamine

Question 15

How can the transmitters be INACTIVATED?

Answer 15

1. Re-uptake of the transmitter back into the neuron (nerve cell terminal).
2. Enzymatic tranformation or degradation.
3. Diffusion away from the receptor.

Question 16

The mechanism of norepinephrine reuptake plays a more important role in the inactivation than the enzymatic action —> Following the re-uptake, the transmitter may be degraded or reused.

Answer 16

KNOW THIS

Question 17

What are the two enzymes that inactivate norepinephrine?

Answer 17

Monoamine Oxidase (MAO) - Inside the neuron
Catechol-O-Methyltransferase (COMT) - outside the neuron.

Question 18

How can you prolong the action of norepineprhine?

Answer 18

1. Re-uptake of the transmitter back in to the neuron (nerve cell terminal).
2. Inhibiting the degradation of norepinephrine by enzyme action.

Question 19

The sympathomimetic drugs are classified into what 3 categories?

Answer 19

1. Direct-acting (directly stimulate the adrenergic receptor)
2. Indirect-acting (Stimulate the release of norepinephrine from the terminal nerve endings)
3. Mixed-acting (Direct and indirect)

Question 20

What are the chemical structures of a substance that can produce a sympathomimetic response?

Answer 20

Catecholamines

Question 21

What are the examples of endogenous Catecholamines?

Answer 21

Epineprhine, Norepineprhine, and Dopamine

Question 22

What are the examples of synthetic Catecholamines?

Answer 22

Isoproterenol and Dobutamine.

Question 23

What do the noncatecholamines do?

Answer 23

Stimulate the adrenergic receptors and have longer duration of action than the endogenous or synthetic catecholamines.

Question 24

What are the examples of noncatecholamines?

Answer 24

Phenynlephrine, Metaproterenol, Albuterol.

Question 25

Nonselective Adrenergic Agonist?

Answer 25

Agonist that affects different adrenergic receptors, which may include additional side effects.

Question 26

What are the pharmacodynamics of Epinephrine?

Answer 26

1. Frequently used in emergencies to treat anaphylaxis (life-threatening allergic reaction).
2. Inotropic (strengthens myocardial contraction) drug that increases cardiac output, promotes vasoconstriction and systolic blood pressure elevation, increases heart rate, and produces bronchodilation.
3. High doses can result in cardiac dysrhythmias necessitating vasoconstriction, thereby decreasing renal perfusion and urinary output.
4. Onset of action and peak concentration times are rapid.
5. The use of decongestant with epinephrine has an additive effect.
6. Beta blockers can antagonize the action.

Question 27

A Beta2 adrenergic agonist SELECTIVE for Beta2-adrenergic receptors, which gives the response of relaxation of bronchial smooth muscle and bronchodilation.

Answer 27

Albuterol sulfate (Proventil)

Question 28

Why may a patient with Asthma tolerate albuterol better than isoproterenol (activates beta1 and beta2 receptors)

Answer 28

Because albuterol’s action is more selective (activates beta2 receptors instead of beta1 and beta2.

Question 29

Pharmacodynamics of Albuterol

Answer 29

1. Prevent and treat bronchospasm.
2. With inhalation the onset of action of albuterol is faster than with oral administration, thought the duration of action is the same for both oral and inhalation preparations.
3. Tremors, restlessness, and nervousness may occur
4. Beta blockers may inhibit the action of albuterol.

Question 30

A selective alpha2-adrenergic agonist used to treat hypertension.

Answer 30

Clonidine (Catapres)

Question 31

Alpha2 drugs act by

Answer 31

Decreasing the release of norepinephrine from sympathetic nerves and decreasing peripheral adrenergic receptor activation.
Produce vasodilation by stimulating alpha2 receptors in the central nervous system (CNS), leading to decrease in blood pressure.

Question 32

An alpha-adrenergic agonist that acts within the CNS. This drug is taken up into the brainstem neurons and converted to methylnorepinephrine, which is an Alpha2-adrenergic agonist that leads to alpha2 activation. The decrease of sympathetic outflow from the CNS causes vasodilation and a reduction in blood pressure

Answer 32

Methyldopa (Aldomet)

Question 33

Side effects of adrenergic agonists

Answer 33

Hypertension, tachycardia, palpitations, restlessness, tremors, dysrhythmias, dizziness, urinary retention, nausea, vomiting, dyspnea, and pulmonary edema.

Question 34

What are the drugs that block the effects of adrenergic neurotransmitters, usually alpha or the beta receptors?

Answer 34

Adrenergic blockers (also adrenergic antagonists, or sympatholytics)

Question 35

How do the Adrenergic blockers work?

Answer 35

Either directly by occupying the receptors or indirectly by inhibiting the release of the epinephrine and norepinephrine.

Question 36

What are the two groups of Alpha Blockers?

Answer 36

Selective (Block Alpha1)

Nonselective (Alpha1 and Alpha2)

Question 37

Why are alpha-adrenergic blockers not prescribed as much as the beta blockers?

Answer 37

Alpha blockers cause orthostatic hypotension and reflex tachycardia.

Question 38

What is the effect of an Alpha blocker?

Answer 38

Vasodilation; 
Decreases blood pressure;
Reflex tachycardia might result;
Miosis (constriction of pupil);
Supresses ejaculation;
Reduces contraction of smooth muscle in bladder neck and prostate gland.

Question 39

Decrease heart heart, which usually follows in decrease of blood pressure.

Answer 39

Beta blockers

Question 40

What are the effects of Beta1 blockers?

Answer 40

Decreases heart rate;

Reduces force of contractions

Question 41

What are the effects of Beta2 blockers?

Answer 41

Constricts bronchioles; contracts uterus; inhibits glycogenolysis, which can decrease blood sugar.

Question 42

Why should nonelective Beta blockers be used with extreme caution in any patient with COPD or asthma?

Answer 42

Because they decrease heart rate and cause brochoconstriction.

Question 43

What is Intrinsic Sympathomimetic Activity (ISA)?

Answer 43

the ability of certain beta blockers to bind with a beta receptor to prevent strong agonists from binding to that receptor producing complete activation.