Radiopharmaceuticals for Drug Development: United States Regulatory Perspective

Henry   F.   VanBrocklin

Abstract

Imaging with radiopharmaceuticals is playing an increasingly important role in the development of new drugs. At nearly every step of the process imaging may be used to assess the status of the candidate drugs and assist in determining the lead molecules for further evaluation. Incorporating imaging studies into the paradigm may ameliorate the temporal and economic cost of drug development. Since 1975 radiopharmaceuticals have been regulated as drugs and all human studies must be carried out under an investigational new drug (IND) or radioactive drug research committee (RDRC) protocol. The FDA released the exploratory IND guidance in 2006 to highlight the flexibility in the IND process while trying to stimulate new drug entry into the approval pipeline. The exploratory IND also provides a lower threshold for radiopharmaceutical and candidate drug first in human studies, using the microdosing concept, that may not be conducted under an RDRC protocol. The RDRC mechanism permits the basic research studies with limited dose and numbers of subjects. The RDRC regulations are 30 years old and the full IND process remains burdensome for radiopharmaceutical development. Therefore, it is essential that the regulatory framework permit the approval of radiopharmaceuticals for use in humans that is commensurate with the safety and applications of the probes.

Keywords: IND application, New Molecular Entity, positron emission tomography, Single photon emission computed tomography, radiopharmaceuticals

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