Comment Letter on Draft Guidance for Developing Medical Imaging Drugs

June 30, 2003

Comment Letter on Draft Guidance for Developing Medical Imaging Drugs

April 14, 1999

Documents Management Branch (HFA-305)
Food and Drug Administration
5630 Fishers Lane
Room 1061
Rockville, MD 20852


Re: Docket No. 98D-0785: Draft Guidance for Industry: Developing Medical Imaging Drugs and Biologics (October 1998)


Dear Sir or Madam:

The Society of Nuclear Medicine (SNM) and the American College of Nuclear Physicians (ACNP) welcome the opportunity to comment on the proposed draft guidance referenced above. With members who are scientists, physicians, pharmacists, and technologists and a membership base totaling over 12,000, we are very informed on how this draft guidance will directly impact the nuclear medicine community and other stakeholders.

We would like to support in general the comments written by the Council on Radionuclides and Radiopharmaceuticals (CORAR). For example, we support reducing the safety testing requirement on radiopharmaceuticals in the group 1 criteria. However, it is our belief that while radiopharmaceuticals are concentrated at much lower doses, the same can not be said of the physical contrast agents used in other imaging techniques such as magnetic resonance or Xray imaging. As such, we do not believe that they should be considered under the same criteria as radiopharmaceuticals.

It is also our combined opinion that the FDA requirement for Phase 1 Data should be changed to include information obtained from non-clinical tests. After all, if non-clinical tests have established the requisite safety factor as well as complete and rapid elimination of the radiopharmaceutical, this should be sufficient data on which to base a conclusion that the drug belongs in Group 1, and can safely be administered to humans in Phase I.

The Draft Guidance states that, in studies intended to demonstrate efficacy; "evaluations of images should be performed by readers that are both independent and blinded…." Blind reads are of concern to our members for a number of reasons, both clinical and technical. Clinically, the information is limited. Nuclear medicine images are not normally interpreted alone, but in blind trials there is no correlation with X-ray, CT, or MRIs. Lab results are not available, and the patient's positioning may be difficult to discern, especially when one is not able to examine the patient. As for the technical problems, image displays may differ from case to case, images may not be presented in temporal sequence, and anatomic markers may not be provided. In simple terms, it is an artificial environment. This is not what happens in a clinical setting and the results, therefore, are not comparable.

Once again, we would like to thank the Food and Drug Administration for allowing the groups and organizations most affected by this guidance document the opportunity to comment. If you should have any questions regarding this matter, please contact Mr. William Uffelman, Director of Public Affairs, at 703-708-9773.


James W. Fletcher, MD
Society of Nuclear Medicine       

James M. Woolfenden, MD
American College of Nuclear Physicians