Comment Re:How about earth? (Score 1) 210
Codene is actually the stereoisomer of heroin, but it doesn't fit most of our receptors so appears mostly inert.
Codeine and heroin are not stereoisomers. They have similar morphine-based structures, but not the same composition. Methylmorphine (codeine) is C18H21NO3. Diacetylmorphine (heroin) is C21H23NO5.
The more famous example is thalidomide. One isomer causes birth defects. The other is effective at countering morning sickness.