ABSTRACT
Clinical trials are an important foundation for the development of new drugs and are the most critical factor during the licensure process of a new biologic. Most drugs and biological products are initially studied in healthy volunteers; subsequent studies are conducted in a much larger, diverse patient population, including those with the disease for which the product is indicated. The stages of clinical trials include phases I to IV. Further trials may be required after licensure and marketing. Although the scientific basis and concept of clinical trials are identical throughout these stages, practical differences exist among the phases. Clinical trials for chemical drugs and biological products are designed to study the efficacy and safety of the product in humans, identify the risk-benefit relationship, and examine the absorption, distribution, and metabolism of the product in healthy people as well as patients. The design of the clinical trials is based on the chemical nature of the product being tested, results of preclinical animal studies, and intended clinical uses. This is particularly relevant for biopharmaceuticals, which frequently demonstrate complex and multiple pharmacological activities. The basis for license approval depends on the adequacy and validity of the trial data available. A larger number of biotechnology-derived products are proceeding in clinical trials at various stages of their development. The progression through these phases is the usual means by which the sponsor collects the data required for evaluation and approval.
