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Flashcards in Pharmacology-Adrenergics Deck (57)
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1
Q

What are the major drugs used for these conditions?

A

*

2
Q

What adrenergic receptors are in the heart, blood vessels. What receptor is on the adrenal gland?

A

Heart = B1. Blood vessels = a1. Adrenal gland = nicotinic (ACh binding stimulates EPI release, which binds to B2 on smooth muscle vascular beds). 

3
Q

Which adrenergic receptor is inhibitory and makes sure NE doesn't have too strong of an effect? How does it work?

A

alpha-2 receptors. They down regulate adenylyl cyclase, open K+ channels (hyperpolarizes) and closes Ca2+ channels via G-protein signal transduction.

4
Q

What is the difference in receptor activation between NE and EPI?

A

NE only activates alpha-1, alpha-2 and beta-1. EPI activates all beta and alpha receptors (including beta-2).

5
Q

Why, in a fight or flight response, do most blood vessels constrict but liver and skeletal blood vessels dilate?

A

Most blood vessels have alpha-1 receptors, which stimulate vasoconstriction when NE binds. Skeletal muscle vasculature and liver vasculature have beta-2 receptors, which stimulate vasodilation when bound by EPI.

6
Q

Binding to what receptor causes bronchiole dilation?

A

EPI binding to Beta-2 receptors

7
Q

Binding of NE to what receptor causes mydriasis?

A

Alpha-1 (pupil dilation)

8
Q

If a woman is going into labor early, what could you give her to relax the uterus?

A

Epinephrine. It stimulates beta-2 receptors that will cause the uterus to relax.

9
Q

Activation of what receptors will result in increased glucose production by the liver? Increased fatty acid release by fat? Decreased insulin secretion? Renin secretion?

A

Liver = alpha-1 and beta-2. Fat = beta-1 and beta-3. Pancreas = alpha-2. Kidney = beta-1.

10
Q

Where are the general locations of these receptors?

A

*

11
Q

Why would phentolamine be a poor choice for controlling hypertension?

A

It is a nonselective alpha-blocker, which will block the alpha-2 receptor, result in increased accumulation of NE and the heart will pump harder.

12
Q

How does binding of NE to alpha-1 receptors cause vasoconstriction?

A

It stimulates G-protein signal transduction that increases Ca2+ and thus muscle contraction.

13
Q

How does binding of NE to beta-1 receptors cause increased heart rate?

A

Gs protein signal transduction results in adenylyl cyclase activity, increases Ca2+ levels and thus increased muscle contraction.

14
Q

How does binding of EPI to beta-2 receptors cause vasodilation in skeletal muscle and the liver?

A

G protein signal transduction results in increased cAMP which relaxes smooth muscle.

15
Q

How does administration of epinephrine affect the nodal action potential in the heart? How does this affect the heart.

A

It decreases phase 4 so you get action potentials more often because it increases Ca++ entry into cardiac myocytes when it binds to beta-1 receptors.

16
Q

How does the level of epinephrine in the blood affect vasculature in smooth muscle?

A

At low levels, beta-2 receptors are stimulated and vessels vasodilate. At high levels, alpha-1 receptors are stimulated and vessels vasoconstrict.

17
Q

When you administer epinephrine to a patient, the heart begins to pump harder due to beta-1 stimulation and systolic blood pressure increases. What would cause the diastolic blood pressure to decrease at the same time?

A

Low doses of epinephrine stimulates mostly beta-2 receptors that vasodilate. This will lower the diastolic pressure. As epinephrine does increases, alpha-1 receptors are stimulated, vasoconstriction occurs and the diastolic pressure will increase.

18
Q

How would this "cat test" look if you administered norepinephrine instead of epinephrine?

A

NE does not stimulate beta-2 receptors so you do not get any vasodilation. The blood pressure will increase significantly and cause vagal reflex to try and bring pressure back down.

19
Q

How would this "cat test" look if you administered isoproterenol instead of NE?

A

Isoproterenol only stimulates beta-1 and beta-2 receptors. Consequently you would see an increase in heart rate from beta-1 stimulation and a decrease in diastolic pressure due to beta-2 stimulation.

20
Q

Why does isoproterenol have lower hyperglycemic effects than epinephrine?

A

It does not act on alpha-1 and thus only beta-2 is stimulated.

21
Q

Why is it important that dopamine is administered at low doses?

A

At low doses, D1,D2 and beta-1 receptors are stimulated, promoting increased cardiac function and vasodilation. At higher doses alpha-1 and alpha-2 receptors are stimulated which vasoconstrict and will raise the blood pressure significantly.

22
Q

What would you expect to see in the "cat experiment" if you gave low dose dopamine instead of epinephrine?

A

Similar results because D1 vasodilates kidney blood vessels and effectively lowers diastolic pressure.

23
Q

What beta-1 agonist is thought to be slightly safer than others when prescribing it to a patient in heart failure?

A

Dobutamine. It increases myocardial contractility more than HR and automaticity.

24
Q

Which of these molecules has an easier time getting into the brain?

A

Amphetamine. It lost its OH group and is less hydrophobic.

25
Q

Why do these molecules have long half lives?

A

Alpha carbon methylation blocks metabolism by MAO (monoamine oxidase)

26
Q

What are the alpha-1 agonists you should know?

A

Phenylephrine. Midodrine.

27
Q

What is the alpha-2 agonist you should know?

A

Clonidine. Lowers blood pressure by activating alpha-2 receptor which in turn inhibits NE release.

28
Q

A patient comes to see you with supra ventricular tachycardia (HR = 132 bpm). How would an alpha-1 agonist help treat this patient?

A

Administration of an alpha-1 agonist like phenlyephrine increases blood pressure, which causes vagal discharge which will in turn slow the heart rate.

29
Q

What drug is used to dilate bronchioles and what receptor does it act on?

A

Albuterol, it acts on beta-2 receptors very specifically.

30
Q

On rotations your attending physician administers a drug to a patient in the ICU to lower his severely high blood pressure and increase blood flow to the kidneys. What drug is this and what receptors does it act on?

A

Fenoldopam. It is a D1 dopamine receptor agonist.

31
Q

You have a patient that is taking phenelzine, a MAOI (monamine oxidase inhibitor) for depression. After a late night eating cheese and drinking beer, what is she at risk for?

A

Widespread vasoconstriction. Tyramine is in fermented foods and can displace NE when MAO is inhibited.

32
Q

What are 5 therapeutic uses for alpha-1 agonists?

A

*

33
Q

A patient comes to see you in clinic and you diagnose her with glaucoma. What adrenergic drug could you prescribe to help with her condition?

A

Alpha-2 agonist brimonidine. It decreases formation of aqueous humor intraocularly. 

34
Q

A patient comes to see you with hypertension. What drug could you prescribe that acts on alpha-2 receptors to help with her condition?

A

Clonidine. It inhibits NE release.

35
Q

What are the different uses of beta-2 agonists?

A

Bronchial asthma, preterm labor delay and treatment of hyperkalemia to induce K+ uptake by muscle.

36
Q

What drug could you prescribe to a patient in cardiogenic shock?

A

Dopamine. It has slight beta-1 receptor activity and increases blood perfusion in the kidneys.

37
Q

What adverse reactions come along with use of alpha-1 agonists?

A

Urinary retention due to constriction of sphincter, hypertension and headache.

38
Q

What adverse reactions come along with use of beta-1 agonists?

A

Increased HR, arrhythmias, and increased oxygen demand.

39
Q

What drug is preferred to phentolamine?

A

Prazosin. Phentolamine competitively blocks alpha-1 and alpha-2 receptors where prazosin only competitively blocks alpha-1 receptors.

40
Q

What drug is preferred to propranolol?

A

Metoprolol. Propranolol blocks beta-1 and beta-2 where metoprolol only blocks beta-1 receptors.

41
Q

Which alpha antagonist is noncompetitive?

A

Phenoxybenzamine covalently binds alpha-1 and alpha-2 receptors.

42
Q

How does the cat react to phentolamine when epinephrine is acting on receptors? What about when NE is acting on receptors?

A

When EPI is acting, HR increases because phentolamine causes a large drop in blood pressure due to alpha-1 blockage. When NE is acting, BP drops because alpha-1 is blocked and peripheral resistance decreases.

43
Q

What are 5 therapeutic uses for alpha antagonists?

A

*

44
Q

When a patient comes into the ER because they have had an erection for 4+ hours after taking Viagra, what do you give them?

A

An alpha-1 agonist to stimulate vasoconstriction.

45
Q

An old man has trouble peeing. What drug can you prescribe to help him get better flow? Why this drug and not phentolamine?

A

Tamsulosin. It is an alpha-1a selective antagonist that relaxes smooth muscle in the urethra to improve urine flow. Phentolamine also blocks alpha-1b, which will lower BP. If your patient already has low BP you want to leave those receptors alone.

46
Q

What adverse effects do you need to be aware of with alpha-1 blockers?

A

*

47
Q

What are the beta receptor antagonists?

A

*

48
Q

A patient comes to see you with a failing heart and no asthmatic issues. What is your drug of choice and why do you need to consider asthmatic issues?

A

Propranolol. You need to consider asthma because the drug also blocks beta-2 receptors which could cause further bronchial constriction.

49
Q

After prescribing propranolol to a hypertensive patient, you see a delayed decrease in blood pressure. Why is this?

A

*

50
Q

You see a patient with high blood pressure and asthmatic problems. What drug do you prescribe and how does this drug utilize the kidneys to decrease blood pressure?

A

Metoprolol. It is a selective beta-1 blocker, leaving beta-2 untouched so bronchioles can remain dilated. It utilizes the kidneys by decreasing beta-1 stimulation of renin secretion.

51
Q

What drugs can cause severe hypoglycemia after insulin administration in diabetics?

A

Any drug that blocks beta-2 or alpha-1. These are the receptors that stimulate glucose release from the liver. Blockage of either of these receptors will cause blood glucose level restoration to take longer after insulin administration.

52
Q

A patient comes to see you with high blood pressure. You decide to prescribe a beta blocker that will have minimal effect on the patient's resting heart rate. What drug do you prescribe?

A

Pindolol. It has intrinsic sympathomimetic activity (slight stimulation of beta-1 with intrinsic NE to keep heart rate normal)

53
Q

What are 8 therapeutic uses of beta blockers?

A

*

54
Q

What are 8 adverse effects of beta blockers?

A

*

55
Q

What drugs are used to treat pheochromocytoma-induced hypertension, hypertensive emergencies, angina pectoris and congestive heart failure?

A

Mixed antagonists. Labetalol and carvedilol (alpha-1 and nonselective beta blockers)

56
Q

What drug is used to control blood pressure and is a neuron blocking agent?

A

Guanethidine. It blocks action potential-induced release of NE, displaces NE from vesicles and sends it for metabolism by MAO, lowering NE levels.

57
Q

What are the positive and negative side effects to using guanethidine?

A

+: does no cross blood-brain barrier. -: depletion of NE = postural hypotension, fluid retention, impaired ability to ejaculate, increased diarrhea and hypotension.

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