Understanding the Regulatory Pathways Used to Develop, Evaluate, Authorize, and Approve New Drugs and Vaccines in the United States.

The United States (U.S.) Food and Drug Administration (FDA) oversees the safety and quality of drugs and vaccines that are used in the U.S. Administration of the FDA falls under the jurisdiction of the U.S. Department of Health and Human Services (HHS). The regulatory oversight of the FDA is complex and comprehensive, requiring the various roles and responsibilities to be divided across six main centers. The activities of two of these centers, the Center for Drug Evaluation and Research (CDER) and the Center for Biologics Evaluation and Research (CBER) are the primary focus of this review.

Evaluation of the Efficacy of Targeted Imaging Agents.

This paper presents our adaptation of Fryback and Thornbury's hierarchical scheme for modeling the efficacy of diagnostic imaging systems. The original scheme was designed to evaluate new medical imaging systems but is less successful when applied to evaluate new radiopharmaceuticals. The proposed adaptation, which is specifically directed toward evaluating targeted imaging agents, has 6 levels: in vitro characterization, in vivo animal studies, initial human studies, impact on clinical care (change in management), impact on patient outcome, and societal efficacy. These levels, particularly the first four, implicitly define the sequence of studies needed to move an agent from the radiochemistry synthesis laboratory to the clinic. Completion of level 4 (impact on clinical care) should be sufficient for initial approval and reimbursement. We hope that the adapted scheme will help streamline the process and assist in bringing new targeted radiopharmaceuticals to approval over the next few years.