Why do so many drugs have 2 names?

[ConkerTheKing]

Examples:
Tamoxifen/Nolvadex
Letrozole/Femara
Cabergoline/Dostinex
Raloxifene/Evista

Etc. Are these European vs American names or something?

 

[Saintinistic]

You will get the generic name for the drug, that identifies it everywhere as that specific drug, and a trade name for it.

Other companies that file for approval to market the drug must use the same generic name but can create their own trade name. So, the same generic drug may be sold under either the generic name or one of many trade names. They can do this once the drug goes off-patent.