The effect of acid modification of porcine mucin on its drug release and skin permeation properties in insulin transdermal patches

The study aimed at determining the effect of acid modified porcine mucin powder on the release and permeation of insulin in transdermal patches. Various batches of insulin patches were prepared by solvent casting method using polysorbate 80 as emulsifying agent and acid treated and untreated mucin powders as base. The patches were evaluated for their physical properties, folding endurance, moisture content and uptake, drug content, bioadhesion, in vitro release, ex vivo permeation and in vivo glucose lowering activity. The prepared insulin patches had a weight range of 0.21-0.27 g, folding endurance of 101-103, moisture content and uptake of 13.73-18.57 % and 11.70-22.30 %, respectively and drug content of 96-101 %. The bioadhesion of the patches prepared with acid treated mucin were within the range of 0.088-0.186 Nm-1 as against 0.055 Nm-1 of the patches prepared with untreated mucin. The in vitro release profiles showed a release of 95 % insulin from patches prepared with untreated mucin within 2 h while the patches made with acid treated mucin gave a release of about 60-73 % over the same time period, indicating a slower release. Animals that received acid treated mucin base insulin patches showed delayed but sustained blood glucose lowering up to 70 %, and 55 % for patches prepared with untreated mucin within 12 h. Insulin transdermal patches prepared with acid modified mucin powder gave superior bioadhesive strength values. They also showed improved drug permeation enhancing ability and achieving up to 70% blood glucose lowering in diabetic rats.