Publications (3)15.77 Total impact
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Article: Hydrogel-Forming Microneedle Arrays for Enhanced Transdermal Drug Delivery.
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ABSTRACT: 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.Advanced Functional Materials 12/2012; 22(23):4879-4890. · 10.18 Impact Factor -
Article: Influence of skin model on in vitro performance of drug-loaded soluble microneedle arrays.
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ABSTRACT: A plethora of studies have described the in vitro assessment of dissolving microneedle (MN) arrays for enhanced transdermal drug delivery, utilising a wide variety of model membranes as a representation of the skin barrier. However, to date, no discussion has taken place with regard to the choice of model skin membrane and the impact this may have on the evaluation of MN performance. In this study, we have, for the first time, critically assessed the most common types of in vitro skin permeation models - a synthetic hydrophobic membrane (Silescol(®) of 75 μm) and neonatal porcine skin of definable thickness (300-350 μm and 700-750 μm) - for evaluating the performance of drug loaded dissolving poly (methyl vinyl ether co maleic acid) (PMVE/MA) MN arrays. It was found that the choice of in vitro skin model had a significant effect on the permeation of a wide range of small hydrophilic molecules released from dissolving MNs. For example, when Silescol(®) was used as the model membrane, the cumulative percentage permeation of methylene blue 24h after the application of dissolvable MNs was found to be only approximately 3.7% of the total methylene blue loaded into the MN device. In comparison, when dermatomed and full thickness neonatal porcine skin were used as a skin model, approximately 67.4% and 47.5% of methylene blue loaded into the MN device was delivered across the skin 24h after the application of MN arrays, respectively. The application of methylene blue loaded MN arrays in a rat model in vivo revealed that the extent of MN-mediated percutaneous delivery achieved was most similar to that predicted from the in vitro investigations employing dermatomed neonatal porcine skin (300-350 μm) as the model skin membrane. On the basis of these results, a wider discussion within the MN community will be necessary to standardise the experimental protocols used for the evaluation and comparison of MN devices.International journal of pharmaceutics 06/2012; 434(1-2):80-9. · 2.96 Impact Factor -
Article: Microneedle arrays as medical devices for enhanced transdermal drug delivery.
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ABSTRACT: In order to exploit the transdermal route for systemic delivery of a wide range of drug molecules, including peptide/protein molecules and genetic material, a means of disrupting the excellent barrier properties of the uppermost layer of the skin, the stratum corneum, must be sought. The use of microneedle (MN) arrays has been proposed as a method to temporarily disrupt the barrier function of the skin and thus enable enhanced transdermal drug delivery. MN arrays consist of a plurality of micron-sized needles, generally ranging from 25 to 2000 µm in height, of a variety of different shapes and composition (e.g., silicon, metal, sugars and biodegradable polymers). The application of such MN arrays to the skin results in the creation of aqueous channels that are orders of magnitude larger than molecular dimensions and, therefore, should readily permit the transport of macromolecules. This article will focus on recent and future developments for MN technology, focusing on the materials used for MN fabrication, the forces required for MN insertion and potential safety aspects that may be involved with the use of MN devices.Expert Review of Medical Devices 07/2011; 8(4):459-82. · 2.63 Impact Factor
