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KK CVII Exam III > Martin - Adrenergic Agonists/Antagonists > Flashcards

Martin - Adrenergic Agonists/Antagonists Flashcards

1
Q

What is the primary NT released from presynaptic neurons in the sympathetic ganglia? What receptor type does it act on?

A

ACh released from presynaptic neurons in sympathetic chain ganglia.

Acts on nicotinic receptors

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2
Q

What is the primary sympathetic NT released from postsynpatic neurons onto cardiac and smooth mm cells?

A

Norepinephrine

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3
Q

What is the major effect of dopamine in the periphery? Through which receptors does it achieve this effect?

A

Dilates renal afferent blood vessels via activation of D1 receptors, thus increasing renal blood flow

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4
Q

What is the effect of norepinephrine on peripheral vascular resistance? Through what receptors does it elicit this effect?

A

Increased peripheral resistance via stimulation of α1 receptors

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5
Q

What is the effect of increased peripheral resistance caused by norepinephrine?

A

Decreased heart rate due to increased baroreceptor reflex activity

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6
Q

What effect does low dose epinephrine have on peripheral resistance?

A

Low dose epi will mildly decrease peripheral resistance

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7
Q

What type of drug is Isoproterenol?

A

Pure β agonist

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8
Q

What effect will isoproterenol have on peripheral resistance?

A

Isoproterenol will cause a major decrease in peripheral resistance

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9
Q

What effect will isoproterenol have on heart rate?

A

Reflex tachycarda due to decrease in peripheral resistance and drop in MAP

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10
Q

What is the difference between low dose and high dose epinephrine?

A

At low doses, epi will cause decreased peripheral resistance via β2 receptors, but at high doses it will cause a marked increase in peripheral resistance due to higher affinity α1 stimulation

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11
Q

What type of drug is phenylephrine?

A

α1-adrenergic agonist, also know as a pressor agent

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12
Q

What does the term “mixed acting α agonist” imply?

A

The drug (i.e. Metaraminol) will directly stimulate α1 receptors, but will also stimulate norepinephrine release

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13
Q

What are the effects of phenylephrine?

A

Vasoconstriction leading to increased peripheral resistance and overall BP, which can cause reflex bradycardia

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14
Q

What agent can be used to block the reflex bradycarda caused by phenylephrine?

A

Atropine

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15
Q

What is phenylephrine used for?

A

Maintain BP in hypotensive states such as spinal anesthesia

Induce the baroreceptor reflex and slowing of the heart in conditions like paroxysmal atrial tachycardia

Nasal decongestant

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16
Q

What are the vascular effects of dopamine? Through what receptor are these effects achieved?

A

Vasodilation of renal, coronary, and mesenteric vascular beds via stimulation of D1 receptors. Main goal is to increase renal blood flow.

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17
Q

What caution must be taken when administering dopamine?

A

BP must be monitored because it will cause α1-mediated vasoconstriction at high concentrations, resulting in end-organ ischemia

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18
Q

What is the order of peripheral receptor activation by increasing concentrations of dopamine?

A

D1 > β1 > α1

19
Q

What is dopamine used for?

A

Increases cardiac output and renal blood flow in cases of shock or CHF

20
Q

What kind of drug is Dobutamine?

A

β1-selective agonist with some α1 agonist/antagonist effects

Mostly has β1 effects

21
Q

What are the effects of Dobutamine?

A

Increased inotropy and some increase in heart rate
Increased cardiac output
Little vascular effect

ONLY USED SHORT TERM

22
Q

What are potential adverse effects of Dobutamine?

A

May increase size of infarct
May cause potential arrhythmias
Increases the work/O2 requirement

23
Q

What is the primary use of α1-selective antagonists?

A

2nd or 3rd line treatment for essential HTN

Usually used in combination with other agents from different drug classes

24
Q

What are the main effects of α1-selective antagonists?

A

Decreased peripheral vascular resistance, venous return, and preload
Usually do not increase HR or CO
No α2 blockade so no increased release of norepi
Lipids: Decreases LDL and TGL, increases HDL

25
Q

What are the main adverse effects of α1-selective antagonists?

A

Postural hypertension and syncope, orthostatic hypotension

26
Q

What is the prototypical α1-selective antagonist?

A

Prazosin

27
Q

What is the prototype nonselective β receptor antagonist (1st generation β blocker)?

A

Propranolol (Inderal)

28
Q

What does it mean if a drug has intrinsic sympathomimetic activity?

A

It is a partial agonist

29
Q

What are some drugs classified as nonselective β receptor antagonists?

A 
Propranolol
Timolol
Nadolol
Pindolol
Carteolol
Sotalol
30
Q

What are the common β1-selective antagonists (2nd generation β blockers)?

A

Atenolol
Metoprolol
Esmolol
Bisoprolol

31
Q

What is the main use and advantage of Esmolol?

A

Used during surgery to control heart rate.

Very short acting, so effects diminish rapidly after stopping infusion.

32
Q

What are the characteristics of the 3rd generation β blockers?

A

Designer drugs that have other activity beyond β blockade:
Combination α and β blockers like Carvedilol and Labetalol
Vasodilators like Betaxolol and Carteolol

33
Q

What are the effects of β blockers when used for HTN?

A

Decreases CO

Produces SLOW decrease in peripheral resistance

34
Q

Clinical uses of β blockers

A

HTN
Ischemic heart disease (angina, MI, ACS)
Thyrotoxicosis

35
Q

Why are β blockers beneficial in pts with ischemic heart disease?

A

Increased catecholamine release during MI increases cardiac work and O2 demand.
β blockers decrease the overall work of the heart and O2 consumption.

36
Q

Role of β blockers in MI and post-MI prophylaxis

A

Reduce risk of arrythmia

Limits spread of infarct size

37
Q

What is the role of β blockers in thyrotoxicosis?

A

Hyperthyroid pts have increased β receptor sensitivity

β blockers reduce the severity of β stimulation, especially in cases of thyroid storm

38
Q

What are the pharmacological effects of β blockers on the heart?

A 
Decreases in OHAIRE:
O2 demand
Heart rate
AV nodal conduction
Infarct size
Rate of ectopic pacemaker depolarization
Exercise tolerance
39
Q

What are the effects of β blockers on renin release?

A

Catecholamines stim β1 receptors in JGA of kidney to increase renin release.
β-blockers inhibit this catecholamine stimulation, thereby decreasing renin release

40
Q

What is a general complication of β blocker use in diabetics?

A

β antagonists block compensatory responses to hypoglycemia

41
Q

What happens if a pt on long-term β-blocker therapy suddenly withdraws from the medication?

A

Pt will have rebound HTN and possibly an infarct due to induced hypersensitivity to β-agonists

42
Q

What do clinical trials show about bisoprolol?

A

Dramatic benefits for CHF pts

43
Q

What type of drug is clonidine and what is its general mechanism?

A

α2 receptor agonists that works centrally to decrease sympathetic outflow

44
Q

What is the result of sudden withdrawal of clonidine?

A

May cause hypertensive crisis that can be life-threatening

KK CVII Exam III (23 decks)

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