Transdermal delivery of insulin using low frequency ultrasound

Repeated insulin injections remain painful for diabetic patients. Intensive research has been focused on the transdermal route as a possible way to drug delivery. For several years now, the use of ultrasound has been proposed in order to increase skin permeability, a phenomenon referred to as sonophoresis. The aim of this study was to optimize all the ultrasound parameters to achieve safe and reproducible sonophoresis of insulin. The experiments reported in this paper were performed on hairless rats using pulsed mode ultrasound (20 kHz). The most relevant results of this study showed that the ultrasound energy is a crucial parameter for skin safety while sonophoresis efficiency appeared to be highly dependant on the net ultrasound exposure time and the pulse "on" duration. Finally, based on these findings, an optimized ultrasound protocol is proposed for rapid transdermal delivery of insulin.