Dermal and transdermal peptide delivery using enhancer molecules and colloidal carrier systems. Part V: Transdermal administration of insulin

In this study, insulin was loaded into non-ionic colloidal carrier systems (CCS) to be used as nano-sized drug delivery systems for transdermal administration. The CCS were characterized for their rheological properties, droplet size and drug loading. Also, the transdermal flux of insulin was estimated using Franz diffusion cells through the epidermis and all the layers of the rats' skin. The efficacy of the administration of the CCS was assessed in vivo transdermally in rats. Based on the rheological properties and droplet size results, the formulated fluids were identified as nano-sized systems having an aqueous colloidal phase, where the hydrophilic peptide is located. Also, a flux of insulin as high as 0.119 ± 0.016 and 1.328 ± 0.047 iu/cm2.h through the rat's skin and epidermis, respectively, could be achieved using CCSIn2. Moreover, the monitoring of the blood sugar level over 6.5 h after a single transdermal administration of CCS exhibited a slight decrease. However, a significant drop in the blood sugar level was observed when they were administered once every two days over 10 days. The developed insulin-loaded CCS containing the penetration enhancer DMSO are nano-sized drug delivery systems and can induce a delayed therapeutic effect by repeating the administration.