Abstract
Polymer-based solid microstructures (MSts) have the potential to significantly increase the quantity and range of drugs that can be administered across the skin. MSt arrays are used to demonstrate their capacity to bypass the skin barrier and enhance permeability by creating microchannels through the stratum corneum, in a minimally invasive manner. This study is designed to demonstrate the ability of MSts to exceed the current boundaries for transdermal delivery of compounds with different molecular weights, partition coefficients, acid dissociation constants, melting points, and water solubilities. In vitro permeation of a range of selected molecules, including acetyl salicylic acid (aspirin), galantamine, selegiline hydrochloride (Sel-HCl), insulin, caffeine, hydrocortisone (HC), hydrocortisone 21-hemisuccinate sodium salt (HC-HS) and bovine serum albumin (BSA) has been studied across excised porcine skin with and without poke and patch application of MSts. Permeation of the molecules was monitored using Franz diffusion cells over 24 h. MSts significantly increased the permeation of all selected molecules up to 40 times, compared to topical applications of the molecules without MSts. The greatest increase in permeation was observed for caffeine with 70 ± 8% permeation and the lowest enhancement was observed for HC with a 2.4 ± 1.3% increase in permeation. The highest obtained flux was BSA (8133 ± 1365 μg/cm2/h) and the lowest flux observed for HC (11 ± 4 μg/cm2/h). BSA and HC also showed the highest (16,275 ± 3078 μg) and the lowest (73 ± 47 μg) permeation amount after 24 h respectively. MSt-treated skin exhibits greatly increased permeation. The molecule parameters (size, acid dissociation constant, partition coefficient and solubility)—traditional hurdles associated with passive diffusion through intact skin—are overcome using MSt skin treatment.
Highlights
Transdermal drug delivery systems are a highly promising method for drug administration, and an alternative drug delivery method to oral administrations
This study presents an investigation of the efficacy of MSts for enhancing transdermal delivery of a range of drug molecules, including acetyl salicylic acid, galantamine, R-(-)-deprenyl hydrochloride (Sel-HCl), insulin, caffeine, hydrocortisone (HC), hydrocortisone 21-hemisuccinate sodium salt (HC-HS) and bovine serum albumin (BSA)
MSt treatment significantly enhanced the permeation of all the selected molecules with different physicochemical characteristics, in comparison to transport through intact skin
Summary
Transdermal drug delivery systems are a highly promising method for drug administration, and an alternative drug delivery method to oral administrations. There are important clinical advantages for topically applied formulations, drug administration via the skin is still quite infrequently used as a first-line approach This is due to the outermost layer of the skin, the stratum corneum, being a highly effective barrier to molecules and drugs, preventing entry of substances into the skin and their subsequent entry into systemic circulation [4,5]. The entire diffusion and partition process is complex, and can be affected by multiple factors including: skin physiological factors, such as age, body site and race [8]; or physicochemical properties of drug formulations, such as partition coefficient, molecular size, solubility, melting point and ionisations [9,10,11] For these reasons, so far, only 20 drugs have shown significant skin permeation suitability [12]. Transdermal delivery of drugs, with one or more parameters outside these confines, through intact skin presents significant challenges in providing sufficient therapeutic doses, when considering drugs with low potency [13,14]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
