Generic Drug (or Generic Equivalent)
Definition: A drug which is exactly the same as a brand name drug and which may be manufactured and marketed after the brand name drug's patent expires (approximately 9-10 years after the brand-name drug entered the market).
Generic drugs cost significantly less than brand name drugs, and are identical in terms of efficacy, safety, side effect profile, and dosing.
Important exceptions to this may include drugs such as immunosuppressants or drugs with a "narrow therapeutic index" such as anti-arrhythmics.
"Narrow therapeutic index" refers to drugs that have a high rate of side effects at commonly administered dosages.