Chloral hydrate is what individuals of a certain age (or just aficionados of dated slang) refer to when they mention “slipping someone a Mickey.” It is a very simple drug, discovered by von Liebig about 175 years ago.
It has largely been supplanted in popularity by the benzodiazepines, which are much better characterized and less toxic (although they’re still addictive). Very small, highly chlorinated molecules like this tend to be hard on your liver, much like carbon tetrachloride and perchloroethylene (“tet” and “perc” to dry cleaners, i’m told).
Chloral may have its safety problems, but the problem here was the mixing of drugs; a number of benzodiazepines were also present: Valium, Klonopin, and Ativan. Also some diphenhydramine, which is a non-benzodiazepine (in fact, it’s an antihistamine with some sedative effects), which you buy as Benadryl, Nyquil, Tylenol PM, etc. I didn’t realize chloral was even really prescribed anymore.
See also The Chem Blog’s writeup of chloral, with some information on its metabolism (text marginally not-safe-for-work.
[Hopefully the first and last Anna-Nicole related MotD.]