Adrenergic Agonists

Question 1

Adrenergic Agonists

Answer 1

• Effects are similar to sympathetic nervous system activation, due to using the same receptors

Question 2

Catecholamines

Answer 2

• All catecholamines:
• Cannotbeusedorally
• Have brief durations of action
• Cannotcrossblood-brainbarrier
• Quickly metabolized by enzymes:
• Monoamineoxidase(MAO)
• Catechol-O-methyltransferase (COMT)
• Both enzymes are present in liver and intestinal wall
• Both have high activity
• Will turn brown or pink in solution once oxidated. Catecholamines should not be used after oxidation occurs

Question 3

Noncatecholamines

Answer 3

Differences from catecholamines: • Metabolized slower
• Not metabolized by COMT • Canbegivenorally
• Cancrossblood-brainbarrier
• All of these differences are due to the loss of the polar catechol group

Question 4

Receptor Specificity

Answer 4

• Receptor specificity is relative

* At high dosages, albuterol will activate beta1 receptors as well as beta2

Question 5

Beta2 Receptors

Answer 5

• Located in lungs and uterus • Therapeutic applications
• Asthma
• Delay of preterm labor • Adverseeffects
• Hyperglycemia
• Tremor

Question 6

Epinephrine

Answer 6

• Receptor specificity: alpha1, alpha2, beta1, beta2 • Therapeuticuses
• Delay absorption of local anesthetics
• Control superficial bleeding
• Elevate blood pressure
• Overcome atrioventricular heart block
• Restorecardiacfunction
• Bronchodilation
• Treating anaphylactic shock

Pharmacokinetics
• Topicalorinjection
• Slowabsorptionduetovasoconstriction • Shorthalf-life
• Metabolized by MAO and COMT

 Adverseeffects
• Hypertensive crisis
• Dysrhythmias
• Anginapectoris
• Necrosisfollowingextravasation • Hyperglycemia

• Drug interactions
• MAOinhibitors
• Tricyclic antidepressants
• Generalanesthetics
• Alpha-adrenergic blocking agents • Beta-adrenergic blocking agents

Question 7

Norepinephrine

Answer 7

• Receptor specificity: alpha1, alpha2, beta1
• Adverse effects identical to epinephrine, except for hyperglycemia
• Therapeutic applications • Hypotensive states
• Cardiacarrest

Question 8

Isoproterenol

Answer 8

• Receptor specificity: beta1, beta2
• Cardiovasculartherapeuticapplications
• Drug interactions identical to epinephrine

Question 9

Dopamine

Answer 9

• Receptor specificity: dopamine, beta1, and alpha1 at high doses
• Therapeuticapplications • Shock
• Heartfailure • Adverseeffects
• Tachycardia
• Dysrhythmia
• Anginal pain

Question 10

Dobutamine

Answer 10

• Receptorspecificity:beta1
• Used to treat heart failure
• Tachycardia
• Should not be taken with MAOIs

Question 11

Phenylephrine

Answer 11

• Receptorspecificity:alpha1
• Administered locally to reduce nasal congestion
• Administered parenterally to elevate blood pressure
• Used to dilate pupils in eye drops
• Coadministered with local anesthetics to delay anesthetic absorption

Question 12

Albuterol

Answer 12

• Receptorspecificity:beta2

* Used to treat asthma through bronchodilation • May cause tremor and tachycardia

Question 13

Ephedrine

Answer 13

• Receptor specificity: alpha1, alpha2, beta1, beta2
• Activates receptors by direct and indirect mechanisms
• Uses are limited due to poor selectivity

Question 14

Prescribing and Monitoring Considerations

Answer 14

• Identifyinghigh-riskpatients
• Greatcaution:Hyperthyroidism,cardiacdysrhythmias,
organic heart disease, or hypertension
• Caution: Angina pectoris, diabetes, and patients receiving MAO inhibitors, tricyclic antidepressants, or general anesthetics