In the US, a drug patent lasts twenty years, if patented after
1995 (17years prior). New drugs usually have multiple patients
covering numerous aspects of the agent and the manufacturing
process. Generics can be introduced after the patent expires.
However, the drug companies apply for the patent when the drug is
discovered, then it has to be studied to prove safety and efficacy
before the drug reaches the market (5-10years) A generic version
typically appears 7-10 years after the patented version.
Originators typically sue generic companies over a number of years
to protect their patents. Originators also have been granted patent
extensions under special circumstances.
