Delivering drugs via nasal spray might overcome a major obstacle to treating brain ailments such as strokes according to researchers.
Based on early studies in rats, researchers from the Stroke Lab and Alzheimer's Research Center in St. Paul, Minnesota, reported that “a direct path from the nose to the brain” could breach the blood-brain barrier, which protects the brain from foreign substances, including drugs.
Senior investigator Dr. William H. Frey II said that his team used a nasal spray to deliver insulin-like growth factor-1, a natural substance that has been shown to protect rat brains from stroke, to tissue deep inside rat brains.
In an interview, Frey said this finding is significant because researchers think this same substance may protect human brains from the devastating effects of stroke, but no one has been able to figure out a way to deliver the drug.
“It stops at the blood-brain barrier,” Frey said. “The only way to get it to the brain would be by drilling a hole in the skull and putting the drug in that way. Not a very practical approach.”
The nasal spray allows the drug to travel to the brain along “neural pathways directly to the brain,” he said. For example, the olfactory system--the sense of smell--has nerve endings “that reach down to the nose.” The drug travels along those pathways directly to the brain, he said. This method, according to Frey, means the drug reaches the brain much faster than it would if it were administered into a vein.
In this study, Frey and colleagues administered the growth factor to 37 male rats in which the researchers induced brain damage that mimics strokes in human brains. They then tested various motor and sensory reflexes to determine if the rats' symptoms were decreased, indicating that the drug had reached its target.
The test results indic ated that the drug had “been successfully diffused in brain tissue,” Frey said. Asked about the implications of Frey's work, Dr. Philip Gorelick, director of the Center for Stroke Research, Chicago, Illinois, said the study was very preliminary but said that it was an intriguing notion. Gorelick pointed out that one of the more daunting aspects of brain research is overcoming the blood brain barrier.
“This might be an option,” Gorelick said, but he noted what works in arat often fails in humans.