[Bro-Mide]

I heard the terms freebase and hydrochloride salt used when taking about pharmaceutical drugs. Can someone explain what is meant by this? I heard that many drugs are amine's which is similar to a freebase. Is hydrochloric acid just mixed with this freebase and the salt precipitates out? Does this mean there is a similar process to turn it back into its freebase form?

Not interested in making drugs always heard these terms thrown around and wondered what the chemistry was behind it.

Any resources on the internet or otherwise about this would be greatly appreciated

[fledarmus]

That's exactly the case. Many drugs are basic amines, and basic amines don't always form the best behaved of solids - some have a tendency to form intractable oils. Usually they crystallize much better if you can find a good salt form. Also, in many cases, the free amine is not water soluble while the salt form is - this can make a difference in how the drug is administered.

There are lists of "pharmaceutically acceptable salt forms" which are essentially acids that can be added to basic drugs to improve properties, but would not cause additional pharmaceutical effects in the body. Hydrochlorides, sulfates, tartrates, maleates,  and dozens of other salt forms have been used.