Medicating through the nose.

Medicating through the nose

Scientists are producing a cornucopia of new peptides and proteins for treating ailments ranging from hypertension to diabetes. But for many of those who might reap the benefits, this biotechnology has been a hard pill to swallow. If the drugs are taken orally, they are decomposed by the digestive system before they can do much good. While injections are an option, scientists are searching for more palatable means of getting drugs into the body.

Researchers at California Biotechnology Inc. in Mountain View, Calif., are looking into the nasal membrane, a cell-layer-thick wall sitting next to a rich blood supply, as an alternative entry route for the new biotech products. According to William Lee, a nasal spray system for delivering insulin has passed the first part of clinical trials, and in animal studies the company has recently succeeded in getting human growth hormone (used for treating pituitary dwarfism) through the nasal cavity.

Insulin, growth hormone and other peptides and proteins are very large molecules which by themselves would not permeate the membrane. So Lee and his colleagues coat the hormone molecules with a small, detergent-like molecule that's a synthetic derivative of a compound produced by fungi. This "not only helps solubilize the drug and stabilize it in solution, but it increases the permeability of the nasal membrane to the drug,' says Lee. "Our best guess at the moment is that the penetration enhancer [temporarily] loosens the binding of proteins between cells,' letting the hormone slip past.

According to Vincent H.L. Lee at the University of Southern California in Los Angeles, researchers are investigating many natural and synthetic enhancers for getting other drugs, vitamins and contraceptives across vaginal, rectal and other areas and through the eye as well as through the nose. How the enhancers do their jobs is being actively studied at the moment, he says. In addition to weakening the binding of membrane cells, some enhancers appear to change the shape of enzymes--which normally prevent drugs from getting into the bloodstream--so that they cannot recognize the drug proteins.