Drugs Could Be Delivered to Brain Via the Nose
Tue May 7, 1:27 PM ET
By Merritt McKinney

NEW YORK (Reuters Health) - Nasal sprays are routinely used to treat conditions that affect the respiratory system such as allergies and nasal congestion, but new research suggests that it may be possible to deliver medication directly to the brain by way of the nose.

For the first time in humans, a nasal spray was used to deliver hormones directly to the brain without entering the bloodstream, reports an international team of scientists led by Dr. Jan Born at the University of Lubeck in Germany.

Although the technique is in the early stages, eventually it may be possible to treat brain diseases and even obesity with nose sprays that deliver molecules called neuropeptides to the brain, Born told Reuters Health.

Neuropeptides, which include hormones such as insulin, are involved in communication within the brain. Developing therapies based on neuropeptides has been tricky, however, since they do not readily cross the blood-brain barrier, a group of cells that controls which substances enter the brain. In addition, side effects may develop if neuropeptides accumulate in the blood. Because of these side effects, doses of peptides given via other methods have had to be too small to have much of an effect on the brain, according to the researchers.

Nasal sprays seem to be an effective way of bypassing the blood-brain barrier, Born's team reports in the advance online edition of the journal Nature Neuroscience. In a study of 27 healthy adults, the researchers used nose sprays to administer the neuropeptides melanocortin, vasopressin and insulin.

Within 80 minutes after participants inhaled the neuropeptides, levels of the hormones in cerebrospinal fluid-the fluid that cushions the brain and spinal cord--increased, with the size of the increase varying from person to person, according to the report. In the case of insulin and melanocortin, blood levels of the hormone did not increase, suggesting that the hormones had entered the brain without passing through the blood first.

However, levels of the third neuropeptide, vasopressin, did increase in the blood.

The study proves "some substances given intranasally can pass directly to the brain" without being absorbed into the blood stream, Born told Reuters Health.

Born suggested that the "nasal route" can now be investigated to see whether neuropeptides can be used to treat brain diseases.

The next step, according to the German researcher, is to identify which neuropeptides might be therapeutically useful.

"Nasal delivery may be useful in the treatment of brain diseases, particularly those involving dysfunction of neuropeptide signaling, such as Alzheimer's disease (news - web sites) and obesity," according to the report.

"Our own research aims at peptides involved in weight regulation, like melanocortins [and] insulin, and in memory function," Born said.

The researchers are also working to improve the brain's ability to absorb the peptides after they have been delivered through the nose.

SOURCE: Nature Neuroscience advance online publication 2002;DOI:10.1038/nn849.