Sympathomimetics Flashcards
Ephedrine dose, onset, peak, duration?
dose: 2.5-10 mg
onset: < 1 minute
peak: 2 - 5 minutes
duration: 10 - 60 minutes
Is ephedrine an alpha 1, alpha 2, beta 1, and/or beta 2 agonist?
INDIRECT alpha 1 and beta 1
Phenylephrine (Neosynephrine) dose, onset, peak, duration?
dose: 40-100 mcg
onset: < 1 minute
peak: 1 minute
duration: 15 - 30 minutes
Is phenylephrine (Neosynephrine) an alpha 1, alpha 2, beta 1, and/or beta 2 agonist?
DIRECT Alpha 1
Epinephrine dose, onset, peak, duration?
dose: 2-20 mcg/min
onset: 30 seconds
peak: 3 minutes
duration: 10 minutes
Alpha 1 stimulation causes?
Increase inotropy and vasoconstriction
Alpha 2 stimulation causes?
Vasodilation due to CNS presynaptic inhibition of norepinephrine
Beta 1 stimulation causes?
Increase inotropy, chronotropy, and dromotropy
Beta 2 stimulation causes?
Increase inotropy, chronotropy, vascular dilation, and bronchial dilation
DA1 stimulation causes?
Vasodilation
DA2 stimulation causes?
Inhibition of norepinephrine release
Is epinephrine an alpha 1, alpha 2, beta 1, and/or beta 2 agonist?
All of the above
Phenylephrine (Neosynephrine) mechanism of action.
DIRECT alpha agonist - binds to and agonizes sympathetic adrenergic Gq-receptors
ultimately stimulates calcium release by the sarcoplasmic reticulum (in arteries and veins, this leads to constriction)
Cardiac effects of phenylephrine.
increases PVR, afterload, and BP
mild increases in chronotropy and inotropy at high doses
How is phenylephrine metabolized?
monoamine oxidase (MAO)
Ephedrine mechanism of action.
INDIRECT alpha 1 and beta 1 agonist - causes norepinephrine to be released, resulting in the stimulation of alpha 1 and beta 1 receptors
DIRECT beta 2 agonist (mild)
Pulmonary and cardiac effects of ephedrine.
pulmonary - mild bronchodilation d/t mild beta 2 stimulation
cardiac - increases PVR, afterload, and BP; increases chronotropy and inotropy; decreases uterine blood flow
How is ephedrine metabolized?
hepatic metabolism
renal elimination
How is epinephrine metabolized?
monoamine oxidase (MAO) and hepatic
What is the dose in mcg/mL of epinephrine 1:200,000? 1:100,000? 1:1000? 1:400,000?
1: 200,000 = 5 mcg/mL
1: 100,000 = 10 mcg/mL
1: 1000 = 1000 mcg/mL (or 1 mg/mL)
1: 400,000 = 2.5 mcg/mL
What medication is used to reverse an overdose of phenylephrine?
hydralazine
What is the max dose of ephedrine? and why?
50mg (the amount that’s in one ephedrine vial)
because any more than that will deplete norepinephine stores. (since ephedrine causes its release)
