March 22, 2023

This is an answer to a common question about the ratios of serotonin to norepinephrine blockade for the SNRIs. In this video I cover the ratios for Venlafaxine (I think I even pronounced it correctly), desvenlafaxine, duloxetine, milnacipran, and levomilnacipran. The winner of this contest may surprise you.

What’s up everybody dr rossi i’m a board certified psychiatrist and if you’re new to the channel i’m going to ask you to go ahead and subscribe to the channel it helps me to know this content matters and it’s working for you as a viewer with that said i’m going to talk a little bit about a question that i get asked all the time and people are asking me like what are

The ratios of serotonin to norepinephrine reuptake inhibition in the snris so i’m going to answer that question here i’m going to break down the most common snris that we prescribe and i’m going to tell you how much serotonin and how much norepinephrine reuptake blockade you get from each so let’s start with effexor or ben lovaxine i think i got it right this time

Hopefully for you guys out there who have uh critiqued me on my pronunciation of ben lafaxine we’ll talk about it a little bit here but anyway effexor 30 to one so that’s what you want to remember with effexor so effexor has a 30-fold higher affinity for the reuptake of serotonin compared to norepinephrine so this is a lot more of a serotonin-based medication than

It is a norepinephrine-based medication and we kind of knew that because you could see that not only in the um in the clinical research but you can kind of see that even in the dosing the dosing has to be much higher to really get that norepinephrine effect moving on to duloxetine or cymbalta so with duloxetine you have a 10-fold higher selectivity for serotonin

Reuptake inhibition compared to norepinephrine reuptake inhibition so we go from 30 to 1 to 10 to 1 so 10-fold higher selectivity for serotonin with duloxetine and then we could talk about desvenlafaxine so desvenlifaxine or prestiq demonstrates a 10-fold higher selectivity for serotonin reuptake inhibition compared to norepinephrine reuptake inhibition so again

Duloxetine pristiq similar in terms of their reuptake their ratios of serotonin reuptake blockade to norepinephrine reuptake blockade so those could be equally used if you prefer with effexor you might want to just jump right to prestige instead of stopping instead of starting with effects the next medication i’m going to talk about is one that’s less familiar to

P people and that is milnasaparan so menasopran is the most balanced of the reuptake inhibitors among the snris which is interesting since nobody really uses it i believe mostly it’s used in fibromyalgia and it’s certainly not a formulary at my hospital and probably many others but anyway milnasapran is the most balanced of the reuptake inhibitors so in terms of

Uh norepinephrine and serotonin reuptake blockade so it’s actually nearly equivalent reuptake blockade so it’s like a one-to-one ratio so it blocks serotonin reuptake and norepinephrine reuptake at about the same amount and according to some sources they actually say the medication has even higher or more neuro-adrenergic effects than serotonergic effects up to

Threefold higher so some sources actually say that milna spran actually has higher norepinephrine reuptake blockade than serotonin so it’s not one to one it’s three to one in favor of norepinephrine now maybe the most unique of the snris is levo milnasapran so this is a derivative of milnaspiren and it demonstrates a twofold greater potency for the norepinephrine

Reuptake inhibitor compared to the serotonin reuptake inhibition so what we see with this one is that there’s actually a two to one ratio in favor of norepinephrine over serotonin reuptake with that said i’ve covered all of the snris for you here that are commonly used in clinical practice if you guys have questions or comments please drop them below and please

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Transcribed from video