Quaaludes fall under the " muscle relaxants" class of drugs, which was generally prescribed as an aid to dela with insomnia due ot the conditions it induced.

they were somewhat freely available aswell since you could get them both as a free base or dilluted in a "salt"(the "disco tablets") but when they became used as a recreational drug this became a problem, since both overdosing on them leads ot nervous system shutdown(aka: coma and eventual Death) and the Lethal dose required drops dramatically if taken with alcohol.

the drug also carried a darker connotation as its properties also made it a choice for a " date rape drug" in the same lines as GHB(except in this case if the prepertrator wasnt careful they could upgrade their assault into manslaughter), and for this it was flagged as a controlled substance.