During the 1990s, the importance of properly designed early trials (Phase I and II) has led to dramatic changes in their design. These changes have included both proper randomized, double blinded designs and increased sample sizes. Although there are different opinions on how best to use data from Phase II in the present process, there is little doubt concerning the high level of information likely to be available at the end of Phase II and the conduct of too many Phase III and IV trials may be considered redundant or unethical .
There are global concerns that activities carried out during the later stages of clinical trials are balancing on the edge of inappropriate activities. Regulatory authorities in Europe have in a sense addressed these issues by their request, in specific situations, for comparative trials of marketed drugs. As the goal of these trials is often to show equivalence, they, however, tend to be more difficult to conduct and to require larger number of patients. Occasionally, global pharmaceutical companies have sought approval on the basis of placebo-controlled trials in the United States and have added active control comparative trials to register in Europe .
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