[Questionsandmorequestions]

Hi,

I have a question and I hope you can help me. Physical chemistry is so hard to grasp for me. The question is:

When 99.9% of a drug is pure but amorphous, do you work with the amorphous compound or do you crystallize it? And why?

[sjb]

What are your thoughts?

What differs between amorphous solids and crystals?

[Questionsandmorequestions]

What are your thoughts?

What differs between amorphous solids and crystals

I know that an amorphous solid is unstable but has a high solubility and dissolution profile. A crystal is stable but can be difficult to dissolve.

But if we let the drug stay amorphous, then all the right conditions should be set that it doesn't crystallize, but if we crystallize then it does not dissolve. Except when we do some modifications like a smaller particle size or add cosolvents...

There's probably a logical answer, but I don't see it.

[Arkcon]

Sorry, but its a little hard to follow your question.  Point by point ...

I know that an amorphous solid is unstable

Maybe you want to use a different term, maybe you mean a particular active, but nothing about being amorphous means unstable to me.  Please define this point more fully.

but has a high solubility

OK.  You mean a particular compound?  Many amorphous compounds aren't more or less soluble than others.

and dissolution profile.

I hope you mean "dissolve" here, in the classical definition for chemistry, as given here:  https://en.wikipedia.org/wiki/Dissolution_(chemistry).  Since you're talking about a drug, you may mean a pharmaceutical, for which you may mean this:  https://en.wikipedia.org/wiki/Dissolution_testing  The topics are very different.

A crystal is stable

No more so than non-crystalline materials.  Unless you mean something other than stable, or again, a particular compound.

but can be difficult to dissolve.

Quartz crystals never dissolve in water.  Sucrose crystals generally do.  What do you mean here.

But if we let the drug stay amorphous, then all the right conditions should be set that it doesn't crystallize, but if we crystallize then it does not dissolve. Except when we do some modifications like a smaller particle size or add cosolvents...

Yes.  Generally, for pharmaceuticals, crystalline or amorphous, the solid is well ground and sieved to a particular particle size.  Well mixed with excipients, and compressed into the proper form.  We need to know more about what you're trying to say.

There's probably a logical answer, but I don't see it.

To what question?