Pharma - Ch.6 - Adrenergic Agonists

What is the difference btw MAO and COMT?

- both inactivate NE, the difference lies in the location COMT= synaptic space/cleft MAO= presynaptic intraneuronally (MAO sits in mitochondria)

Where in the body can we find MAO?

- intraneurally - Gut wall - Liver

Indication of Oxymetazoline?

- nasal decongestants - ophthalmic drops for the relief of redness of the eyes associated with swimming, colds, and contact lenses

Which drugs block reuptake of NE via sodium-chloride (Na+/Cl-)-dependent norepinephrine transporter (NET) ?

- tricyclic antidepressants (TCAs), such as imipramine) - serotonin-norepinephrine reuptake inhibitors (duloxetine, cocaine)

Which will contract your detrusor muscle, ACh or NE?

ACh

Which of the following is correct regarding responses mediated by adrenergic receptors? A. Stimulation of α1 receptors increases blood pressure. B. Stimulation of α1 receptors reduces blood pressure. C. Stimulation of sympathetic presynaptic α2 receptors increases norepinephrine release. D. Stimulation of β2 receptors increases heart rate (tachycardia). E. Stimulation of β2 receptors causes bronchoconstriction.

Correct answer = A. Stimulation of α1 receptors, mostly found in the blood vessels, causes vasoconstriction and increase in blood pressure. Stimulation of α2 receptors on the sympathetic presynaptic terminal reduces the release of norepinephrine. β2 receptors are not found in the heart, so activation of β2 receptors does not affect heart rate. Stimulation of β2 receptors found in the bronchial tissues causes bronchodilation, not bronchoconstriction.

An asthma patient was given a nonselective β agonist to relieve bronchoconstriction. Which of the following adverse effects would you expect to see in this patient? A. Bradycardia. B. Tachycardia. C. Hypotension (reduction in blood pressure). D. Worsening bronchoconstriction.

Correct answer = B. A nonselective β agonist activates both β1 as well as β2 receptors. β1 activation causes an increase in heart rate (tachycardia), contractility, and subsequent increase in blood pressure. It relieves bronchoconstriction because of the β2 receptor activation

A 70-year-old patient was brought to the emergency room with a blood pressure of 76/60 mm Hg, tachycardia, and low cardiac output. He was diagnosed with acute heart failure. Which of the following drugs would be the most appropriate to improve his cardiac function? A. Epinephrine. B. Fenoldopam. C. Dobutamine. D. Isoproterenol.

Correct answer = C. Among the choices, the ideal drug to increase contractility of the heart in acute heart failure is dobutamine, since it is a selective β1-adrenergic agonist. Fenoldopam is a dopamine agonist used to treat severe hypertension. Other drugs are nonselective adrenergic agonists that could cause unwanted side effects.

A hypertensive patient was accidentally given an α2 agonist instead of an α1 blocker. Which of the following is correct in this situation? A. α2 Agonists can increase the release of norepinephrine from sympathetic nerve terminals. B. α2 Agonists can reduce blood pressure in this patient. C. α2 Agonists can increase blood pressure in this patient. D. α2 Agonists will not affect blood pressure in this patient.

Correct answer = B. α2 Agonists activate α2 receptors located in the presynaptic terminal of sympathetic neurons and cause a reduction in the release of norepinephrine from sympathetic nerve terminals. This leads to a reduction in blood pressure. α2 Agonists such as clonidine and methyldopa are therefore used as antihypertensive agents.

Which of the following adrenergic agonists is commonly present in nasal sprays available over-the-counter (OTC) to treat nasal congestion? A. Clonidine. B. Albuterol. C. Oxymetazoline. D. Dobutamine. E. Norepinephrine.

Correct answer = C. Drugs with selective α1 agonistic activity are commonly used as nasal decongestants because of their ability to cause vasoconstriction in the nasal vessels. Oxymetazoline is an α1 agonist and therefore the preferred drug among the choices as a nasal decongestant. Clonidine is an α2 agonist, albuterol is a β2 agonist, dobutamine is a β1 agonist, and norepinephrine is a nonselective adrenergic agonist.

Which of the following is correct regarding adrenergic neurotransmission? A. Epinephrine is the major neurotransmitter released from sympathetic nerve terminals. B. Norepinephrine is mainly released from the adrenal glands. C. Tricyclic antidepressants and cocaine prevent reuptake of norepinephrine into the nerve terminals. D. Monoamine oxidase (MAO) converts dopamine to norepinephrine in the nerve terminal.

Correct answer = C. Tricyclic antidepressants (TCAs) and cocaine inhibit the transporter protein that prevents the reuptake of norepinephrine into the sympathetic nerve terminals. Norepinephrine, not epinephrine, is the major neurotransmitter released from sympathetic nerve terminals. Epinephrine, not norepinephrine, is mainly released from the adrenal glands. Dopamine is converted to norepinephrine by dopamine β-hydroxylase, not by MAO.

A 12-year-old boy who is allergic to peanuts was brought to the emergency room after accidentally consuming peanuts contained in fast food. He is in anaphylactic shock. Which of the following drugs would be most appropriate to treat this patient? A. Norepinephrine. B. Phenylephrine. C. Dobutamine. D. Epinephrine.

Correct answer = D. Norepinephrine has more α agonistic effects and activates mainly α1, α2, and β1 receptors. Epinephrine has more β agonistic effects and activates mainly α1, α2, β1, and β2 receptors. Phenylephrine has predominantly α effects and activates mainly α1 receptors. Dobutamine mainly activates β1 receptors and has no significant effects on β2 receptors. Thus, epinephrine is the drug of choice in anaphylactic shock that can both stimulate the heart (β1 activation) and dilate bronchioles (β2 activation).

One of your patients who is hypertensive and gets mild asthma attacks occasionally bought an herbal remedy online to help with his asthma. He is not on any asthma medications currently but is receiving a β1-selective blocker for his hypertension. The herbal remedy seems to relieve his asthma attacks, but his blood pressure seems to increase despite the β-blocker therapy. Which of the following drugs is most likely present in the herbal remedy he is taking? A. Phenylephrine. B. Norepinephrine. C. Dobutamine. D. Ephedrine. E. Salmeterol.

Correct answer = D. Two drugs among the choices that could relieve asthma are ephedrine and salmeterol, as they activate β2 receptors in the bronchioles and cause bronchodilation. However, salmeterol is a selective β2 agonist and should not cause an increase in blood pressure. Ephedrine on the other hand stimulates the release of norepinephrine and acts as a direct agonist at α- and β-adrenergic receptors, thus causing an increase in blood pressure. Phenylephrine (a nonselective α agonist) does not cause bronchodilation. Norepinephrine is a nonselective adrenergic agonist that does not have any stimulatory effects on β2 receptors. Also, norepinephrine is not active when given orally.

All of the following are correct regarding adrenergic receptors, except: A. α1 Receptors are primarily located on the postsynaptic membrane in the effector organs. B. α2 Receptors are primarily located on the presynaptic sympathetic nerve terminals. C. β1 Receptors are found mainly in the heart. D. β2 Receptors are found mainly in adipose tissue

Correct answer = D. α1 Receptors are located on the postsynaptic membrane in the effector organs such as blood vessels. α2 Receptors are mainly found on the presynaptic sympathetic nerve terminals, where they inhibit the release of norepinephrine when activated. β1 Receptors are found in the heart, in addition to some other tissues, and cause increase in heart rate and contractility when activated. β2 receptors are found in the lungs, in addition to some other tissues, and cause relaxation of bronchial smooth muscles when activated. β3 Receptors are found in adipose tissue and are involved in lipolysis.

Which of the following adrenergic agonists is most likely to cause CNS side effects when administered systemically? A. Epinephrine. B. Norepinephrine. C. Isoproterenol. D. Dopamine. E. Ephedrine.

Correct answer = E. Ephedrine is more lipophilic compared to the other drugs listed and therefore is more likely to cross the blood-brain barrier when administered systemically. Therefore, ephedrine is more likely to cause CNS side effects compared to other listed drugs

Which would make you retain urine, NE or ACh?

NE

Dobutamine should be used with caution in .........., because it increases AV conduction

atrial fibrillation

Phenylephrine binds to....?

alpha 1

Oxymetazoline binds to which receptors?

alpha 1 and 2

Who turns NE into it inactive form

catechol-O-methyltransferase (COMT)

Which would cause urination, cholinergic or adrenergic agonists?

cholinergic agonists

Epinephrine can cause arrythmias, especially when given with ...?

digoxin

Which drug blocks the release of NE from the vesicles?

guanethidine

Mirabegron ....... the levels of digoxin:

increases

The most common side effects of clonidine are?

lethargy, sedation, constipation, and xerostomia

Which drugs blocks the storage of dopamine in the adrenergic neuron?

reserpine

Most common AE of Albuterol and terbutaline?

tremor

tamsulosin is a selective....?

α1A antagonist that is used to treat benign prostatic hyperplasia