http://www.fda.gov/fdac/special/newdrug/begin.html Animal Testing
In animal testing, Kuntzman says, drug companies make every effort to use as few animals as possible and to ensure their humane and proper care. Two or more species are typically tested, since a drug may affect one differently from another. Such tests show whether a potential drug has toxic side effects and what its safety is at different doses. The results "point the way for human testing and, much later, product labeling,'' Kuntzman says.
So far, research has aimed at discovering what a drug does to the body. Now, it must also find out what the body does to the drug. So, in animal testing, scientists measure how much of a drug is absorbed into the blood, how it is broken down chemically in the body, the toxicity of its breakdown products (metabolites), and how quickly the drug and its metabolites are excreted from the body. Sometimes such tests find a metabolite that is more effective than the drug originally picked for development.
Of particular concern is how much of the drug is absorbed into the blood. "If a drug's active ingredients don't get into the blood,'' Kuntzman says, ''it won't work.'' Scientists may add other chemicals to the drug to help the body absorb it or, on the other side, to prevent it from being broken down and excreted too soon. Such changes in the drug's structure mean even more testing.
Absorption rates can cause a host of problems. For example, for a certain drug to be effective, 75 percent of it may need to reach the bloodstream. But absorption rates can vary among individuals from, say, 10 to 80 percent. So, the drug must be able to produce the desired effects in those who absorb only 10 percent, but not cause intolerable side effects in people who absorb 80 percent.
''If we can improve the absorption rate we can reduce the variation in what real dosages people would be subject to,'' Kuntzman says. A more standard absorption rate for all individuals, say around 75 to 80 percent, would mean that the dose could be reduced and still have the desired effects.
As for testing on humans- sure you wouldn't have difficulty finding volunteers Thatguy and I would be more than willing participants in the trial- but there are structured and specific guidelines that need to be met- it isn't feasible to test on humans (particularly in this case)- it's an extremely complex, and expensive testing process-
