Generic drugs go through what the Food and Drug Administration calls an abbreviated approval process.

But it takes three times as long as FDA reviews of new experimental drugs because of the sheer volume of applications, many of which are submitted years before the original drug's patent will expire.

There are now more than 2,400 generic drug applications awaiting FDA approval. Generic drugs are comparable to brand-name "innovator" drugs in performance, intended use, strength, dosage form, route of administration and quality. Because of that, their effectiveness and safety aren't tested in animals and people.

Instead, the maker must prove scientifically that a generic drug performs the same as the original one in people, meaning the same amount of active ingredients enters the bloodstream in the same amount of time. Often, that's done by giving healthy volunteers the generic drug, then taking blood samples to test the level of the drug over time. FDA staff also review chemistry and sterility data on the proposed generic, plus information that would go on the detailed package insert, and inspect the factory where it would be made.