How to Make an Atomic Drug

Melissa Marino, Ph.D.
Published: February, 2006

Ronald Baldwin, Ph.D., prepares radiopharmaceuticals in a shielded cabinet with the help of robotic arms.
Photo by Anne Rayner
Robert Baldwin, Ph.D., is on the front lines of a major national effort to develop new radiotracers, not only to improve understanding of brain diseases but to speed drug development.

It’s an ambitious task.

At the heart of radiopharmaceutical preparation is the cyclotron—a hulking machine entombed by thick concrete shielding with a control panel resembling the cockpit of a jet airliner.

The cyclotron accelerates charged particles, usually protons, in dizzying circles to near the speed of light, until they are sent smashing into a sample of nonradioactive material (carbon, fluorine, oxygen or nitrogen). This collision forces an extra proton into the target atom’s nucleus, resulting in a radioisotope that can then be inserted into the pharmaceutical compound—again, not always an easy feat.

To improve safety, ever decreasing amounts of radiation are incorporated into radiopharmaceuticals, making simple chemical reactions tricky.

“There’s a lot of art in radiochemistry… a lot of reactions that are ‘bread and butter’ bench reactions just don’t work,” Baldwin says, because of the low concentrations of radioisotope used.

With the initiative to develop several new radiopharmaceuticals for both brain and cancer imaging, he has his work cut out for him.

Baldwin doesn’t seem to mind, though. He just wants folks to remember where the brilliant images on the screen originated.

“Chemists are often in the background,” he says with a smile. “People sometimes forget where (the images) came from.”

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