Design, Optimization and Characterisation of Polymeric Microneedle Arrays Prepared by a Novel Laser-Based Micromoulding Technique

• Published in: Pharmaceutical research Vol. 28; no. 1; pp. 41 - 57
• Main Authors: Donnelly, Ryan F., Majithiya, Rita, Singh, Thakur Raghu Raj, Morrow, Desmond I. J., Garland, Martin J., Demir, Yusuf K., Migalska, Katarzyna, Ryan, Elizabeth, Gillen, David, Scott, Christopher J., Woolfson, A. David
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01-01-2011; Springer Nature B.V
• Subjects: Animals; Biochemistry; Biomedical and Life Sciences; Biomedical Engineering and Bioengineering; Biomedicine; Drug Delivery Systems - instrumentation; Drug Delivery Systems - methods; Equipment Design; Humans; In Vitro Techniques; Injection molding; Injections, Intradermal; Lasers; Medical Law; Microinjections - instrumentation; Microinjections - methods; Models, Biological; Needles; Pharmaceutical sciences; Pharmacology/Toxicology; Pharmacy; Polymers; Polymers - chemistry; Production methods; Research Paper; Silicones - chemistry; Skin - metabolism; Skin - ultrastructure; Solubility; Swine; Technology, Pharmaceutical - methods; Tomography, Optical Coherence; Transdermal medication; laser engineering; microneedles; optical coherence tomography; transdermal drug delivery
• ISSN: 0724-8741; 1573-904X
• DOI: 10.1007/s11095-010-0169-8

ABSTRACT
Purpose
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 OCT-informed 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.