doi:10.1038/nindia.2013.44 Published online 28 March 2013
Researchers have devised a new, nanosized drug carrier that can be used to deliver insulin orally1 . They made the carrier by modifying a starch-derived compound with a non-toxic polymer. This nanosized drug vehicle can transport insulin to target tissues, while retaining the efficacy of the insulin molecule.
Starch, a natural biodegradable polymer, is widely used in the food and plastic industries. It readily reacts with water, but chemical modification can cause it to repel water, making it an excellent drug carrier. The modified polymer can sequester and protect drug molecules in its water-repelling core until the drug is delivered to target tissues. However, previous studies had not explored this concept to deliver insulin orally.
The researchers synthesized starch acetate by reacting starch with acetic anhydride in the presence of sodium hydroxide catalyst. The starch acetate was then modified by polyethylene glycol, a non-toxic polymer. Adding the modified starch acetate to insulin solution led to the formation of self-aggregated insulin-loaded nanoparticles.
They found that rat intestinal mucosa showed significant uptake of insulin-loaded nanoparticles. A 20% release of insulin was observed in gastric fluid over a period of 2 hours, whereas 60% release was observed in intestinal fluid over 8 hours. Experiments with mouse fibroblast cells suggest that the drug-loaded nanoparticles are non-toxic.
"These nanoparticles can be used as an oral delivery formulation for insulin that might provide a prolonged glucose-lowering effect in diabetic patients," says Willi Paul, a co-author of the study.