Oral insulin may be one step closer to becoming available to people who now have to take shots for their diabetes.
Scientists in Taiwan report success in early tests of an oral insulin solution in diabetic rats. The solution hasn't been tested in people yet.
Currently, insulin can be taken by injection or, as in the case of the recently approved Exubera, by inhalation.
"Multiple daily injections of insulin are currently the standard treatment for insulin-dependent diabetic patients," write the Taiwanese researchers, who include Hsing-Wen Sung, PhD, of Taiwan's National Tsing Hua University.
An oral drug would be "by far the most convenient and comfortable way of delivering insulin," Sung's team writes.
But there have been roadblocks. "Protein drugs, like insulin, are readily degraded" in the stomach, preventing pure oral insulin from reaching the bloodstream to do its work, the researchers point out.
So Sung and colleagues bundled insulin with chitosan -- a chemical derived from the shells of shrimp, crabs, and lobsters -- into tiny particles called nanoparticles.
They then put these nanoparticles in an oral solution, which they tested on diabetic male rats.
Lab tests showed the insulin reached the rats' bloodstream and lowered their blood glucose (sugar) levels.
Further work is needed to see if the oral insulin solution works in people. Other scientists have also attempted to make an oral insulin solution, but none have reached the market.
The Taiwanese study appears in the journal Biomacromolecules.
By Miranda Hitti, reviewed by Louise Chang, MD
SOURCES: Lin, Y. Biomacromolecules, Jan. 8, 2007; vol 8: pp 146-152. WebMD Medical News: "Study Probes Weight Loss Supplement Chitosan." News release, American Chemical Society.