April 20, 2009

Drug May Prevent Side Effects Of Radiation Exposure

Researchers at the Armed Forces Radiobiology Research Institute in Bethesda, Maryland, reported Sunday that two compounds in a class of bone-strengthening drugs known as bisphosphonates may protect people exposed to radiation from developing leukemia -- a common long-term side effect of radiation exposure.

The scientists said the compounds delayed and in some cases even prevented mice exposed to high doses of radiation from developing leukemia.

Alexandra Miller, who has been studying ways to protect astronauts and military personnel from radiation exposure, presented the study's findings at the American Association for Cancer Research in Denver, Colorado.

The study could help cancer patients who received radiation treatment and later developed leukemia as a side effect, she said.

Miller studied a bisphosphonate compound known as ethane-1-hydroxy-1 and 1-bisphosphonate, or EHBP, which is chemically similar to Procter & Gamble's osteoporosis drug Didronel or etidronate. She also studied an experimental drug called CAPBP, which is similar to Roche's Boniva or ibandronate, she said.

She chose these drugs because previous studies involving humans had suggested that bisphosphonates might prevent cancer from spreading to the bone.  The medications have also have been shown to remove uranium from the body.

In conducting the study, Miller exposed lab mice to radiation in strong enough doses to cause leukemia.  She then injected some of the mice with one of the two compounds.

Mice exposed to such radiation would typically develop leukemia and die 92 to 110 days later.

However, "with the drug, the animals were developing leukemia too, but it took much longer, 150 to 170 days," Miller told Reuters.

"The total number that actually developed leukemia was significantly lower with both of the drugs."

Although all of the untreated mice developed leukemia after radiation exposure, only half of the treated group did, she noted.

"It was very significant. We didn't have any toxic effects with the drug treatment," she said.

Miller said additional studies are needed before the drugs could be used in humans. However, she believes the compounds have potential to address one of the most toxic and lethal side effects of radiation exposure.


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