Originally Posted by
ralfp
Eszopiclone is the active stereoisomer of zopiclone. It exists as a separate drug from zopiclone because of patent reasons; there's no motivation to go through the FDA approval process for an off-patent drug.
AFAIK the side effect profile of the two is the same.
Which for me is mild "hangover" and severe metal mouth for most of the entire next day. I can't drink water the next day until the evening.