Adrenergic Agents Flashcards
What is the mechanism of action of Phenylephrine?
Alpha-1 adrenergic receptor agonist
What is a typical IV bolus dose of phenylephrine in anesthesia practice?
100 mcg
What is a primary clinical use of phenylephrine during surgery?
Hypotension treatment
Phenylephrine is most likely to cause which of the following side effects?
Reflex Bradycardia
What is the typical duration of action for IV phenylephrine?
10-15 minutes
Is Phenylephrine a pure alpha-1 adrenergic agonist?
Yes
Does Phenylephrine increase both blood pressure and heart rate?
No (It increases BP but may cause reflex bradycardia.)
Is Phenylephrine commonly used to treat intraoperative hypotension?
Yes
Is the onset of IV phenylephrine usually within 15–30 minutes?
No (Onset is typically within 30 seconds to 2 minutes.)
Can Phenylephrine be used as a nasal decongestant?
Yes
What is the onset time of IV phenylephrine?
Typically 30 seconds to 2 minutes
How long does IV phenylephrine typically last?
10-15 minutes
What is one common cardiovascular side effect of phenylephrine?
Reflex bradycardia
In what surgical or clinical scenario would phenylephrine be preferred over ephedrine?
In a patient with hypotension and tachycardia, where increasing blood pressure without stimulating the heart is preferred.
Describe the mechanism of action of phenylephrine.
Phenylephrine stimulates alpha-1 adrenergic receptors, leading to vasoconstriction and increased systemic vascular resistance (SVR), which elevates blood pressure
Is a tachyphylaxis effect possibly seen with Phenylephrine (Neosynephrine) infusions?
Yes, titrate up as time goes on to negate
What receptors does epinephrine primarily act on?
Alpha-1, Beta-1, and Beta-2 (But also Alpha-2)
What is the typical IV bolus dose of epinephrine in ACLS for cardiac arrest?
0.5 - 1 mg
What is the onset of action for IV epinephrine?
30–90 seconds
Which of the following is NOT a common side effect of epinephrine?
Bradycardia
Epinephrine is the first-line treatment for which condition?
Anaphylaxis
Does Epinephrine cause both vasoconstriction and bronchodilation?
Yes
Do the effects of epinephrine last approximately 1–4 hours?
No (Effects are typically short-acting, lasting 5–10 minutes IV.)
Can Epinephrine be administered via intramuscular, subcutaneous, and IV routes?
Yes
Does Epinephrine only stimulate beta receptors?
No (It stimulates both alpha and beta receptors.)
Is Epinephrine contraindicated in anaphylaxis due to its cardiac effects?
No
What is the recommended IM dose of epinephrine for anaphylaxis in adults?
0.3–0.5 mg IM every 5–15 minutes as needed
Describe the mechanism of action of epinephrine.
Epinephrine is a non-selective adrenergic agonist that stimulates alpha-1 (vasoconstriction), beta-1 (increased heart rate and contractility), and beta-2 (bronchodilation and vasodilation) receptors.
What are three clinical uses for epinephrine?
Anaphylaxis, cardiac arrest, and severe asthma exacerbations.
What are two cardiovascular side effects of epinephrine?
Tachycardia and hypertension
What is the duration of action of IV epinephrine?
Approximately 5–10 minutes
In which clinical scenario would epinephrine be preferred over norepinephrine?
In anaphylaxis due to its combined alpha and beta agonist effects, including bronchodilation.
How are Epinephrine infusions made?
1 mg into a 250 ml bag of NS (typical bolus is 5-20 mcg)
What is the typical IV bolus dose of ephedrine for hypotension?
5–10 mg
What is the approximate onset time of IV ephedrine?
1–2 minutes
How long does the effect of a single IV dose of ephedrine typically last?
10–60 minutes
Which best describes the mechanism of action of ephedrine?
Direct and indirect sympathomimetic action
Which clinical situation is ephedrine commonly used in?
Hypotension due to spinal or epidural anesthesia
Does Ephedrine increase blood pressure primarily through vasoconstriction and increased cardiac output?
Yes
Is Ephedrine contraindicated in patients with tachycardia?
Yes
Are the effects of ephedrine shorter than those of phenylephrine?
No (Ephedrine generally has a longer duration.)
Does Ephedrine directly stimulate alpha and beta receptors and indirectly increases norepinephrine release?
Yes
Is Ephedrine metabolized quickly by monoamine oxidase (MAO)?
No (It is relatively resistant to MAO metabolism.)
What is the IV dosage range of ephedrine for treating hypotension?
5–10 mg IV bolus, repeated as needed up to a total dose of ~50 mg
How does ephedrine work to increase blood pressure?
It acts as both a direct alpha/beta agonist and indirectly by stimulating norepinephrine release.
What is the onset and duration of IV ephedrine?
Onset: 1–2 minutes; Duration: 10–60 minutes
Name three side effects of ephedrine.
Tachycardia, hypertension, anxiety.
In what clinical scenario would you prefer ephedrine over phenylephrine?
When hypotension is accompanied by bradycardia, since ephedrine increases both heart rate and blood pressure.
What is the typical initial IV infusion dose for norepinephrine in hypotensive patients?
4-16 mcg
What is the primary receptor type activated by norepinephrine?
Alpha-1 primarily, with some Beta-1 (some Alpha-2)
Norepinephrine is most commonly used to treat which condition?
Septic shock-related hypotension
What is the approximate onset of action of norepinephrine when given IV?
Immediate (within 1 minute)
Which of the following is a common side effect of norepinephrine?
Reflex bradycardia
Does Norepinephrine increase both systemic vascular resistance and heart rate?
No (It increases SVR and may cause reflex bradycardia.)
Is the duration of action of norepinephrine approximately 1–2 minutes after discontinuation?
Yes
Is Norepinephrine primarily an alpha-2 adrenergic receptor agonist?
No (It primarily stimulates alpha-1 receptors.)
Can Extravasation of norepinephrine cause tissue necrosis?
Yes
Is Norepinephrine the first-line vasopressor for septic shock?
Yes
What is the usual starting dose of norepinephrine in adults?
2–4 mcg/min IV infusion, titrated to effect, typically given as infusion due to very short half-life
What receptors does norepinephrine stimulate and what are the effects?
Alpha-1 (vasoconstriction leads to ↑ SVR & BP), Beta-1 (↑ contractility and cardiac output), minimal Beta-2 effects.
What is the onset and duration of IV norepinephrine?
Onset: Immediate (within 1 minute); Duration: 1–2 minutes after stopping infusion.
List three common side effects of norepinephrine.
Hypertension, reflex bradycardia, ischemia (extremities, mesenteric, or myocardial).
Why is norepinephrine preferred over dopamine in septic shock?
It provides more predictable vasopressor effects with less arrhythmogenic potential.
What is the typical IV bolus dose of labetalol?
5 mg, followed by doses of 5-20mg depending on desired ABP
What is the primary mechanism of action of labetalol?
Non-selective beta blocker with alpha-1 blocking activity (7:1)
Which of the following is NOT a typical side effect of labetalol?
Reflex tachycardia
How long after IV administration does labetalol typically begin to work?
2–5 minutes
Labetalol is commonly used in which of the following clinical scenarios?
Acute hypertension in pregnancy
Does Labetalol block both alpha-1 and beta-adrenergic receptors?
Yes
Is the duration of action of IV labetalol typically 6–8 hours?
No (It’s approximately 2–4 hours.)
Is Labetalol safe to use in patients with asthma?
No (It may cause bronchospasm due to beta-2 blockade.)
Can Labetalol lower blood pressure without significantly affecting heart rate?
Yes
Should Labetalol be avoided in patients with second or third-degree heart block?
Yes
What is the IV onset time for labetalol?
2 to 5 minutes
What is the mechanism of action of labetalol?
Labetalol is a mixed alpha-1 and non-selective beta-adrenergic receptor blocker that reduces blood pressure by decreasing systemic vascular resistance and heart rate.
List three common side effects of labetalol.
Bradycardia, hypotension, dizziness
What is the typical IV bolus dose and repeat dosing interval for labetalol in hypertensive emergency?
10–20 mg IV initially, then may repeat or double every 10 minutes until desired BP or up to 300 mg total
When is labetalol commonly used?
Hypertensive emergencies, perioperative hypertension, and acute hypertension during pregnancy (e.g., preeclampsia).
What is the mechanism of action of Esmolol?
Beta-1 selective antagonist
What is the typical IV bolus dose of Esmolol?
10-20 mg
What is the onset time for Esmolol when given IV?
30–60 seconds
Which of the following is a primary clinical use for Esmolol?
Rapid heart rate control in supraventricular tachycardia
What is the approximate duration of action of Esmolol?
10–20 minutes
Does Esmolol have a rapid onset and a short duration of action?
Yes
Is Esmolol metabolized primarily by the liver?
No — It is metabolized by plasma esterases.
Is Esmolol commonly used to manage acute tachycardia and intraoperative hypertension?
Yes
Is Esmolol a non-selective beta-blocker?
No — It is beta-1 selective.
Is Esmolol contraindicated in patients with bronchial asthma?
Yes
What is the onset time for IV Esmolol?
30–60 seconds
Describe the mechanism of action of Esmolol.
Esmolol is a cardioselective beta-1 adrenergic receptor blocker that decreases heart rate and myocardial oxygen demand.
What is the half-life of Esmolol, and how is it metabolized?
Half-life is about 9 minutes; metabolized by plasma esterases.
List two clinical scenarios where Esmolol is commonly used.
Control of supraventricular tachycardia, perioperative hypertension
Name three side effects of Esmolol.
Bradycardia, hypotension, heart block
What is the primary mechanism of action of Metoprolol?
Beta-1 selective antagonist
What is the typical IV dose of Metoprolol?
1-2 mg
What is the onset of action of intravenous Metoprolol?
5–10 minutes
Which of the following is NOT a common side effect of Metoprolol?
Seizures
In which clinical scenario would Metoprolol be most appropriate?
Managing atrial fibrillation with rapid ventricular response (sustained tachycardia)
Is Metoprolol selective for beta-1 adrenergic receptors at low doses?
Yes
Is Metoprolol rapidly metabolized by plasma esterases?
No — It is metabolized by the liver (CYP2D6).
Is one of the major uses of Metoprolol to control hypertension and arrhythmias?
Yes
Should Metoprolol be used with caution in patients with heart block or severe bradycardia?
Yes
Does Metoprolol have an effect on myocardial oxygen demand?
Yes — It reduces oxygen demand by decreasing heart rate and contractility.
What is the onset time of IV Metoprolol?
Approximately 5–10 minutes
Is Metoprolol the most common beta blocker a patient will be on?
Yes
Describe how Metoprolol affects cardiac function.
It reduces heart rate, myocardial contractility, and cardiac output by selectively blocking beta-1 receptors.
Name two clinical indications for Metoprolol use.
Atrial fibrillation with RVR, hypertension, angina, myocardial infarction.
List three common side effects of Metoprolol.
Bradycardia, hypotension, fatigue, dizziness, and bronchospasm (especially in high doses or non-selective forms).
