Phase I
In this phase a drug is first administered to humans to determine safety, side effects, and tolerability. Phase I clinical trials look at absorption, distribution, metabolism, and excretion from the body. Usually a preferred method of administration is determined. Approximately twenty to eighty healthy volunteers are given the drug, and are watched under constant supervision with tests to check all safety measures. This phase takes anywhere from one to three years. Only about twenty percent of drugs that make it to Phase I testing go on to receive final FDA approval.
