Chemical Name

• Researchers assign a chemical name to newly created drugs that reflect the medication's molecular structure. This complex name then becomes abbreviated into a shorter name that makes it easier on scientists who have to refer to this name often. The Merck Manuals list RU 486 as an example shorthand name.
  
  

Trade Name

• The Food and Drug Administration (FDA) assigns a trade name once they approve the drug for human use. The company marketing the drug creates the trade name. The medication sells under this name alone until the patent expires. At that point, the manufacturer can sell it under the trade or generic name.
  
  

Generic Name

• The United States Adoptive Name (USAN) Council chooses the drug's generic name. Generic names tend to be harder to remember than trade names. Doctors and researchers writing about the medication use the generic name because it doesn't refer to a particular manufacturer. But prescribing doctors usually use the trade name.
  
  

Other Companies

• When a patent on a medication expires, other companies may use the generic name already approved for the drug. Or the company can apply to the FDA for a new brand name for that same medication.
  
  

Patents

• A patent covers the drug for 20 years with extensions possible. That period covers back to the creation of the drug, which may happen 10 years before the medication receives approval for use in humans.