By Elizabeth Lopatto
(Bloomberg) -- Botulinum neurotoxin type A, sold as Allergan Inc.'s Botox remedy for wrinkles, can move from its injection site to the brain, a study shows.
Scientists injected rats' whisker muscles with botulism toxin. Tests of the rodents' brain tissue found that botulism had been transported to the brain stems, the researchers said in the Journal of Neuroscience published April 2.
Mouse and rat physiology is different from that of humans, so the results may not predict what happens in people, Avram said. He wasn't involved in the study.
Myobloc is botulinum neurotoxin type B, a different type of botulinum than studied, said Edgar Salazar-Grueso, chief medical officer of Solstice Neurosciences, in a telephone interview today.
Scientists injected botulism toxin into one side of the hippocampus in each rodent brain, and into their superior colliculus, a visual center. From one side of the hippocampus, the toxin migrated to the opposite. From the visual center, the drug went to the animals' eyes.
Higher doses of Botox are injected to treat limb spasms in children with cerebral palsy in about 60 countries. Some U.S. doctors use it for this purpose, though Allergan doesn't market it in the U.S. for the unapproved use. A typical cosmetic dose is about 10 times less than a dose for cerebral palsy, Avram said.