Sustained release of insulin through skin by intradermal microdelivery system.

An intradermal microdelivery system comprising a wafer having 150-mum long microneedles and an applicator was used for controlled release of insulin. Insulin was topically applied on microneedle-pretreated skin. In vitro percutaneous studies showed that the penetration amount of FITC-Insulin following microneedle pretreatment was enhanced significantly and continued to increase for several hours after the removal of donor phase. In vivo studies on diabetic rats confirmed that the pharmacodynamic profile of percutaneously administrated regular insulin was smooth, with the duration of action comparable to that of subcutaneously injected biphasic insulin. The effects of insulin concentration, duration and area of microneedle treatment on blood glucose lowering were studied in vivo. The results indicated that the duration of microneedle treatment and insulin concentration were key influencing factors to optimize blood glucose control. The extent of blood glucose lowering was in proportion to the area of microneedle treatment.