ABSTRACT
Each stage drug research has its own significance, but the results do not necessarily carry over from one stage to the next. For example, the effects of the drug being studied on isolated rat liver in the test tube may be observed and measured. When the same drug is given to a living rat, however, the effects may not be similar. The rat liver in its normal anatomic setting is affected by multiple factors may reinforce, distort, or otherwise alter the action of the drug being studed. Clinical testing is even more complicated. Humans are more complex than other animals, as well as chemically different in some respects. Futhermore, people have highly developed nervous systems, hence emotions feelings, which affect them in elaborate and as yet poorly understood ways.
