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How to preserve aqueous solutions (clorazepate, picamilon) ?

B

Bauhaus

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Jul 12, 2014
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Clorazepate & picamilon powder are highly soluble in water, but sparingly soluble in ethanol.
How do you preserve those aqueous solutions ? You can't add ethanol since they might precipitate.
Any advice ?
 
In pharmaceutical water solutions, benzyl alcohol is often used as a preservative, but I think it can cause allergic reactions to some people. Not sure about sodium benzoate which is used as a food preservative.
 
Bauhaus said:
Clorazepate & picamilon powder are highly soluble in water, but sparingly soluble in ethanol.
How do you preserve those aqueous solutions ? You can't add ethanol since they might precipitate.
Any advice ?
Click to expand...

freeze drying
 
Benzyl alcohol seems to be mainly used for intravenous & topical medications.

I'll look into the freeze drying process.
 
You can use BA for oral preparations. It tastes foul, but it works fine at a low %.
 
Benzyl alcohol is actually pretty foul smelling even at 0.9% w/v in water. In fact, most of its close relatives smell funny too... methyl benzoate is overpoweringly floral (hyacinth?), benzaldehyde is cloyingly almond-like, and benzonitrile is the same.

Maybe that's just me. But I'd find it hard to drink a solution of benzyl alcohol, not that you're meant to do that anyway.

Won't clorazepate degrade in solution by decarboxylation to nordazepam, being a beta-keto-acid?
 
Last edited:
sekio said:
Won't clorazepate degrade in solution by decarboxylation to nordazepam, being a beta-keto-acid?
Click to expand...

Apparently it only takes about 10 minutes for a dose of clorazepate to be almost completely converted to nordazepam in the human stomach, so yes, it does "degrade" rapidly once it is protonated into its free acid form.

Clorazepate is much more stable in its anionic form, which is why it is generally sold as "clorazepate dipotassium" (or "potassium clorazepate.KOH", if you will). Still, even as an alkaline salt, its stability in an aqueous solution might not be that great.
Not that this is really a problem though, because clorazepate itself is presumably inactive before being turned into nordazepam.

That said... I don't see why you couldn't create a solution of clorazepate from diluted alcohol. 20% ethanol in water should still be able to dissolve it at common dosages (diazepam solutions are typically around 5 mg per mL, which would be equivalent to about 10 mg of clorazepate per mL).
 
Hodor said:
That said... I don't see why you couldn't create a solution of clorazepate from diluted alcohol. 20% ethanol in water should still be able to dissolve it at common dosages (diazepam solutions are typically around 5 mg per mL, which would be equivalent to about 10 mg of clorazepate per mL).
Click to expand...
That seemed to work. Thanks.
 
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