[Facilitated transdermal delivery of insulin by pulse current iontophoresis]

Facilitated transdermal delivery of insulin by pulse current iontophoresis was investigated. It was found that pulse current iontophoresis can increase the transdermal permeation rate, and there was a positive correlation between reservoir insulin concentration and skin permeation rate of insulin. Moreover, when the reservoir solution pH (3.6) was below the isoelectric point of insulin (pI 5.2), the transdermal permeation rate of insulin was the highest, 324.3 +/- 33.4 microU/(cm2.h). When the pH of the reservoir solution was brought up to 7.4, the transdermal permeation rate of insulin declined markedly to 143.7 +/- 27.3 microU/(cm2.h). When the reservoir solution pH was close to the isoelectric point of insulin, the transdermal permeation rate of insulin was the lowest, 78.4 +/- 21.9 microU/(cm2.h).