Here's a nice piece on generic's. Most of the article was pro generics, but they do point out this:
Patients benefit from lower costs, but a generic substitute may not always be the best fit. For one, a generic drug's inactive ingredients often differ from those of the brand-name version, which may cause allergic reactions or other problems for a small percentage of patients.
Also, patients may simply metabolize different drugs in different ways, said Sandy Walsh, spokeswoman for the U.S. Food and Drug Administration.
But in general, patients shouldn't fear generics.
"As far as the agency is concerned, they're approved to be exact copies," Walsh said.
Still, when it comes to serious medical conditions, doctors say even the slightest change in a drug regimen may have negative consequences.
KY = The fact is anybody can have an idiosynchratic reaction to any drug. (side effects) You can find stories where people do better on the generic than the brand, More than 70% of all scripts are substituted for with generics. If one comes we will lose most of our market share
As for the your other question type in Drug Master File Decitabine into your browser. There are 4 approvals the first one in 1998 is the one Dacogen uses. The other 3 are from weill known raw materail suppliers to generic companies