This technology may allow for oral administration of drugs that previously could only be given by injection, notes Wei-Chiang Shen, Ph.D., professor and acting chair of the Department of Pharmaceutical Sciences. Shen, along with colleagues David Ann, Ph.D., professor of molecular pharmacology and toxicology, and Yun Bai, doctoral student in the Department of Pharmaceutical Sciences, wrote a paper on this research that will appear in the May 17 issue of the Proceedings of the National Academy of Sciences (PNAS), which is currently available online.
"Many of today's oral medications are made from small molecules, like amino acids or lipids, and their permeability allows them to be absorbed from the intestine into the body," says Shen. "On the other hand, protein-based drugs are large and bulky, which can prevent them from crossing the intestine and gaining access to the sites where they are needed. They are also very sensitive to digestive enzymes and may be destroyed by stomach acid before they can be absorbed." To sidestep the difficulty of getting these large protein drugs through the GI tract intact, pharmaceutical scientists have looked at other ways to deliver protein-based drugs-such as via needle-free injections or through inhalation. But, these delivery methods pose their own significant challenges. Ultimately, Shen and colleagues began to reconsider the possibilities of oral drug administration.
Their first breakthrough came when they began to recognize the potential uses of transferrin. "We discovered that transferrin can bind t