Insulin Microneedle Patches Of Greatly Improved Transdermal Drug Delivery Based On Rapid Freezing 3D Printing

Insulin non-injection preparations have been studied since 1922.Over the past 97 years,oral,inhalation,nasal spray and other preparations have been tried but have not been successful.Since 1998,the drug-forming properties of transdermal microneedle patches have been favored by the industry,including phase-transition microneedles invented in our laboratory.Phase-transition insulin microneedle patch relies on swelling release to avoid polymer deposition in the skin,achieving more accurate transdermal administration and effectively control of postprandial glycemic.However,production efficiency and transdermal absorption rate need to be further improved before treatment.In order to solve the above problems,our laboratory has invented the rapid freezing 3D printing process of freeze-line drawing,which not only makes the microneedle patch production efficiency greatly exceed the current mold casting,but also can greatly improve insulin penetration and skin absorption rate through needle shape optimization.This study used the new process to optimize the microneedle shape by adjusting the various printing parameters and controlling variables to achieve a substantial increase in insulin transdermal absorption rate.In the experimental details,the study specifically examined the temperature,viscosity of the liquid,the material of the print head,the vertical displacement speed of the print head,the injection rate of the microneedle-forming material,and the influence and regulation of the drying procedure on the microneedle shape.Furthermore,the optimal balance point between the microneedle strength and the effective specific volume was selected,and the thin waist-shaped insulin microneedle patch was prepared and optimized.Finally,this study compared the transdermal absorption rate of the optimized thin waist-shaped microneedle patch and cone microneedle patch prepared by 3D printing and the mold-concave cone microneedle patch by dermal layer simulation in vitro transdermal delivery test.The cumulative release rate of the microneedle(53.4%)was substantially higher than that of the cone microneedle(29.5%)and the mold-cast microneedle(20.6%).