Abstract
Phase IV studies, which are commonly referred to as "postmarketing surveillance (PMS)" or pharma-coepidemiological studies, play an important role in evaluating the long-term safety of medicines. The system for conducting PMS in Japan consists of three components; spontaneous reporting of side effects, "reexamination of newly marketed agents" and "reevaluation of agents used in practice." The reevaluation is to be repeated at given intervals. However, the present system applied for PMS has many problems which must be solved. Particularly in regard to antihypertensive therapy, since most hypertensive patients are required to take antihypertensive agents for the rest of their life, scientifically sound PMS is indispensable. In this article, the present system for PMS in Japan will be overviewed, the preliminary results of prospective phase IV studies which are being conducted to evaluate the long-term efficacy and safety of calcium antagonists will be reported, and some proposals will be mentioned to improve phase IV studies, PMS, on the basis of the preliminary results which are currently available. (Hypertens Res 1992; 15: 121-126)
