Who gets tested in Phase I Trials? As many as 80 healthy or sick human beings. Phase I trials occur after animal tissue and whole-animal studies have determined that the agent appears safe and effective for its intended use. This stage discerns mainly whether the agent is safe for humans and provides data to determine the pharmacological effects. Phase I studies, which last from two to six months, are observed closely so that the entire trial can be stopped if adverse side effects occur. About 77% of the agents pass Phase I.
What about Phase II Trials? As many as several hundred patients with the actual disease participate. Again, determining safety is the primary aim of this stage, but efficacy landmarks also are set. This phase involves control subjects and can last as long as two years. About 33% of all assessed drugs pass Phase II.
And Phase III Trials? ...
