External control of drug release: controlled release of insulin from a hydrophilic polymer implant by ultrasound irradiation in diabetic rats.

The development of a polymeric system capable of delivering insulin in-vivo at increased rates on demand by an external ultrasound irradiation is reported. Implants composed of EVA1 copolymer and insulin were placed subcutaneously in diabetic rats. When the diabetic rats receiving implants containing insulin were exposed to an ultrasound irradiation, a sharp drop in the blood glucose levels was observed after the irradiation, indicating a rapid rate of release of insulin in the implanted site.