Two drugs to treat lethal radiation exposure
It was long thought that the effects of exposure to high doses of radiation were instant and irreversible. The gut is destroyed and the loss of bone marrow cells damages blood-cell production and the immune system.
New research shows that 2 compounds – already approved for use in people – may treat radiation sickness even after exposure. Right now, it works, increasing survival in mice. Nature News reports.
While exposure to radiation is relatively easy to detect, there are few treatment options. And last’s year’s nuclear accident in Fukushima renewed anxiety over this lacking.
As a precaution against mass radiation poisoning, governments stock granulocyte colony-stimulating factor; boosts bone marrow function, but must be kept refrigerated, has occasional side effects, and must be taken as soon as possible.
“Most people think the game is over after you have the damage,” says Hartmut Geiger at the Cincinnati Children’s Hospital Medical Center. “Now, we know you can modify that.”
Geiger and colleagues have found a therapeutic strategy that can be deployed up to 24 hours after radiation exposure.
- Thrombomodulin (Solulin/Recomodulin) is currently approved in Japan to prevent thrombosis.
- Activated protein C (Xigris), made by Eli Lilly in Indianapolis, was a leading drug for treating inflammation from blood poisoning until it was pulled from the US market last October because of a lack of efficacy.
Treating mice with either drug led to an eightfold increase in key bone marrow cells (pictured) needed for the production of white blood cells, and improved the survival rates of mice receiving lethal radiation doses by 40–80%.
- Mice were injected with activated protein C after being exposed for 24 hours.
- A month later, 70% of the injected mice were still alive, whereas only 30% of the uninjected mice had survived.
- Thrombomodulin also increases survival, but must be administered within 30 minutes of radiation exposure to be effective.
The compounds add to a growing arsenal of anti-radiation drugs currently being investigated. And in addition to environmental exposures, they open the potential for new treatments against radiation toxicity during cancer treatment.
The work was published in Nature Medicine this week.
[Via Nature News]
Image: Geiger et al., Nature Medicine