clarification

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chicamedica

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Is dexmedetomidine the S-enantiomer or the D-enantiomer of medetomidine. I've seen some sources say S- (including baby miller), other sources say D- . The drug's name suggests that it's the D-enantiomer. Probably not too crucial of a detail but the chemistry nerd in me is bothered.

Which is it?
 
chicamedica said:
Is dexmedetomidine the S-enantiomer or the D-enantiomer of medetomidine. I've seen some sources say S- (including baby miller), other sources say D- . The drug's name suggests that it's the D-enantiomer. Probably not too crucial of a detail but the chemistry nerd in me is bothered.

Which is it?
Click to expand...

Couldn't it be both? IIRC, enantiomers are classified as D vs L or R vs S (or + v -); these different systems are based on different properties of the compound (rotation of polarized light vs geometry of structure, etc...). Also, entirely possible that I'm way off given that I haven't really touched organic chem in ~10 yrs.
 
enantiomers are non-superimposable mirror image compounds which are divided into dextrorotatory (Latin: dexter, right) or levorotatory (latin: laevus, left) depending on how a substance rotates the plane of polarization. A racemic mixture is an equal mix of both.
R and S configurations are in relation to the configuration around the chiral, or center, carbon. They are specified as R (latin: rectus, right) or S (latin: sinister, left) {reference Morrison & Boyd's Organic Chemistry 5th edition-yes I still own it} This is done by assigning priorities to the ligands attached to the chiral carbon in the center based on atomic numbers and, I believe, is beyond the scope of the question.
In short, Dexmedetomidine is the dextroisomer of medetomidine (reference-Anesthetic Pharmacology-Evers and Maze Pg 479), just as the name implies. I am unsure of the R vs S configuration of dex.
 
lushmd said:
Couldn't it be both? IIRC, enantiomers are classified as D vs L or R vs S (or + v -); these different systems are based on different properties of the compound (rotation of polarized light vs geometry of structure, etc...). Also, entirely possible that I'm way off given that I haven't really touched organic chem in ~10 yrs.
Click to expand...

Yes.

There is also a difference between d and D. IIRC little d is dextrorotary and big D has to do with the chirality of the first carbon of the fisher projection of a carbohydrate.
 
Ok clear now!

So, dexmetedomidine is the S-enantiomer, which happens to be dextrorotatory :. S(+)-metedomidine.

Been a while since organic chem for me as well. Thanks everyone!
 
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