Unique microneedle arrays prepared from crosslinked polymers, which contain no drug themselves, are described. They rapidly take up skin interstitial fluid upon skin insertion to form continuous, unblockable, hydrogel conduits from attached patch-type drug reservoirs to the dermal microcirculation. Importantly, such microneedles, which can be fabricated in a wide range of patch sizes and microneedle geometries, can be easily sterilized, resist hole closure while in place, and are removed completely intact from the skin. Delivery of macromolecules is no longer limited to what can be loaded into the microneedles themselves and transdermal drug delivery is now controlled by the crosslink density of the hydrogel system rather than the stratum corneum, while electrically modulated delivery is also a unique feature. This technology has the potential to overcome the limitations of conventional microneedle designs and greatly increase the range of the type of drug that is deliverable transdermally, with ensuing benefits for industry, healthcare providers and, ultimately, patients.

Europe PMC Funders Author ManuscriptsPurpose-Design and evaluation of a novel laser-based method for micromoulding of microneedle arrays from polymeric materials under ambient conditions. The aim of this study was to optimise polymeric composition and assess the performance of microneedle devices that possess different geometries.Methods-A range of microneedle geometries was engineered into silicone micromoulds, and their physicochemical features were subsequently characterised.Results-Microneedles micromoulded from 20% w/w aqueous blends of the mucoadhesive copolymer Gantrez® AN-139 were surprisingly found to possess superior physical strength than those produced from commonly used pharma polymers. Gantrez® AN-139 microneedles, 600 μm and 900 μm in height, penetrated neonatal porcine skin with low application forces (>0.03 N per microneedle). When theophylline was loaded into 600 μm microneedles, 83% of the incorporated drug was delivered across neonatal porcine skin over 24 h. Optical coherence tomography (OCT) showed that drug-free 600 μm Gantrez® AN-139 microneedles punctured the stratum corneum barrier of human skin in vivo and extended approximately 460 μm into the skin. However, the entirety of the microneedle lengths was not inserted.Conclusion-In this study, we have shown that a novel laser engineering method can be used in micromoulding of polymeric microneedle arrays. We are currently carrying out an extensive OCTinformed study investigating the influence of microneedle array geometry on skin penetration depth, with a view to enhanced transdermal drug delivery from optimised laser-engineered Gantrez® AN-139 microneedles.

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The purpose of the present study was to develop intranasal delivery systems of sumatriptan using thermoreversible polymer Pluronic F127 (PF127) and mucoadhesive polymer Carbopol 934P (C934P). Formulations were modulated so as to have gelation temperature below 34°C to ensure gelation at physiological temperature after intranasal administration. Gelation temperature was determined by physical appearance as well as by rheological measurement. The gelation temperatures of the formulations decreased by addition of increasing concentrations of Carbopol (ie, from 29°C for 18% PF127 to 23.9°C for 18% PF127, 0.5% Carbopol). The mucoadhesive force in terms of detachment stress, determined using sheep nasal mucosal membrane, increased with increasing concentration of Carbopol. The results of in vitro drug permeation studies across sheep nasal mucosa indicate that effective permeation coefficient could be significantly increased by using in situ gelling formulation with Carbopol concentration 0.3% or greater. Finally, histopathological examination did not detect any damage during in vitro permeation studies. In conclusion, the PF127 gel formulation of sumatriptan with in situ gelling and mucoadhesive properties with increased permeation rate is promising for prolonging nasal residence time and thereby nasal absorption.

The main purpose of this work was to develop an oral microemulsion formulation for enhancing the bioavailability of acyclovir. A Labrafac-based microemulsion formulation with Labrasol as surfactant and Plurol Oleique as cosurfactant was developed for oral delivery of acyclovir. Phase behavior and solubilization capacity of the microemulsion system were characterized, and in vivo oral absorption of acyclovir from the microemulsion was investigated in rats. A single isotropic region, which was considered to be a bicontinuous microemulsion, was found in the pseudoternary phase diagrams developed at various Labrasol:Plurol Oleique:Labrafac ratios. With the increase of Labrasol concentration, the microemulsion region area and the amount of water and Labrafac solubilized into the microemulsion system increased; however, the increase of Plurol Oleique percentage produced opposite effects. The microemulsion system was also investigated in terms of other characteristics, such as interfacial tension, viscosity, pH, refractive index, diffusion, and bioavailability. Acyclovir, a poorly soluble drug, displayed high solubility in a microemulsion formulation using Labrafac (10%), Labrasol (32%), Plurol Oleique (8%), and water (50%). The in vitro intraduodenal diffusion and in vivo study revealed an increase of bioavailability (12.78 times) after oral administration of the microemulsion formulation as compared with the commercially available tablets.