Nuclear docs ask FDA to broaden agent tests

The Society of Nuclear Medicine would like to see Food and DrugAdministration approval of imaging radiopharmaceuticals expedited.SNM representatives have met with the FDA on several occasionsto discuss possible avenues to quicker authorization.

The society would prefer to have nuclear agents evaluated onthe basis of physiologic function rather than their efficacy inimaging particular disease states, said Dr. Naomi Alazraki, SNMpresident.

The FDA appears amenable to the idea, but would require radiopharmaceuticalmanufacturers to fashion their applications in such a manner,she said.

"They (the FDA) have responded positively. They said (physiologicfunction) would be a valid option for criteria setting in evaluatinga radioactive drug. If the manufacturer said this is how it wanted(the agent) judged, FDA would accept that," she said. "Thiswould be a more efficient strategy in getting drugs through theFDA, but it is a decision the manufacturers would make."

The first two nuclear brain imaging agents--Spectamine fromMedi-Physics and Ceretec from Amersham--were approved for examinationof stroke, noted Dr. Michael Devous, president of the SNM's brainimaging council. But these agents are useful in diagnosing manyother brain diseases as well, including epilepsy, dementia anddepression, he said.

"We felt that (approval just for stroke) was restrictiveand not good for nuclear medicine," Devous said. "Sowe asked the FDA to consider approvals based on the functionalbehavior of the radiopharmaceutical and not on the disease. Weare looking for them to accept approvals for brain blood-flowagents."

The same argument holds true for nuclear heart agents, Alazrakisaid. Why not assess cardiac radiopharmaceuticals according totheir accuracy in imaging myocardial perfusion, rather then theirsensitivity and specificity for imaging myocardial ischemia?

"If the physician wants to use an agent that images myocardialperfusion in a patient he expects has myocardial ischemia, that'spart of the practice of medicine," she said.

Contrast agents for use in CT, MR and other imaging modalitiesare treated more efficiently than radiopharmaceuticals in theFDA approval process, Devous said.

"Contrast agents are always approved as contrast agents.When they're approved, you can use them to look at kidneys, brains,hearts or legs. Radiopharmaceuticals are treated and reviewedlike drugs. The documentation required of the companies are thoseof therapeutic drugs," he said.

"I'm not trying to make drug companies' lives easier,but we have an opportunity to provide a unique service to patients.We need these new radiopharmaceuticals," Devous said.