Saturday, June 13, 2020

Clinical correlates: Epinephrine vs Norepinephrine reversal

Hey Awesome peeps :)

This post is about variation in the effects of epi- and norepinephrine depending on its dose.

Epinephrine (low-dose) acts similar to isoproterenol (due to high sensitivity of beta receptors; beta before alpha)
Epinephrine (high-dose) - same effects as norepinephrine (alpha-1 > alpha-2 > beta-1)

Alpha-1 effects of epinephrine and norepinephrine cause hypertensive changes in the blood vessels (vasoconsriction). On adding alpha-1 selective blockers (-osins), ie., epinephrine reversal, leads to rather abrupt fall in blood pressure (hypotension). This occurs due to unmasking of beta-2 receptors.

On the other hand, norepinephrine reversal does not result in hypotension (the blood pressure just returns to normal due to alpha-1 block). This is because norepinephrine does not act on beta-2 receptors. (mnemonic on receptors)

That's all
Hope it helps :)
- Jaskunwar Singh

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