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Q: Valproic acid & Sodium valproate
Resp sir,
i am a
patient's friend from india. My friend has been prescribed for acute manic
episodes with a combination of 2:1 of Na valp + Valproic acid 200mg b.i.d dosing
whereas i came across a medical friend of mine who had suggested to ask the dr
to prescribe Divalproex sodium 250mg which as per him is a better version of
Valproate than the brand(Epilex Chrono)with a 1:1 molar conc of NaValp +
Valproic acid. How do they differ from each other?, for the dr also was confused
when this question was put to him. pl help with a differentiation between the 2
molecules.
Thanks,
Dear Sir --
Readers with a better organic chemistry background than I may be able to make
more of the distinction I'm about to describe, which you've basically already
figured out:
Forms of the active ingredient,
the valproate ion (you could think of that as V-)
- Sodium valproate (V. Na;
dissolving into V- and Na+ when it hits the
water of the stomach)
- Valproic acid (V. H); dissolving
into V- and H+ when it hits the water of the
stomach)
- Combinations of the two
a) "divalproex sodium" (U.S.: Depakote; Canada:
Epival), which is a 1:1 mixture
b) some 2:1 mixture your friend is taking, which is not
available -- to my knowledge -- in the U.S. (Epilex Chrono, if I interpret
you correctly)
Now, does it make any difference? I'm not aware
of any literature comparing the two mixtures (1:1 versus 2:1). There could
be such a literature (send me some if you find it). From what I know so
far, always open to learning more, it shouldn't make any difference in the effectiveness
of the medications, because all of these forms end up yielding the valproate
ion which is the active form of the medication. The difference is said
to be, as I understand it, that the combinations are better in terms of side
effects than the Sodium Valproate version (in the U.S., that's Depakene).
The latter causes much more stomach irritation and thus nausea.
So if your friend is not having stomach problems with
the current one, and there's no other reason to look at switching, I don't think
there would be any improvement to be had from switching. Again, I could be
wrong, let me know if you learn otherwise. Thanks. A basic reference
from a solid source on this which I consulted for this reply is
http://www.miminc.org/sample_dival01.html
.
Dr. Phelps
Published January, 2003
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