Micropatch ™ Microneedle System

Background

Microneedles are a recent invention arising from the application of etching and lithographic techniques from semiconductor fabrication processes, to produce sharp high aspect ratio solid or hollow features on plastics or metals. These have found potential applications as a mechanism for the delivery of drugs and various therapeutic molecules. The range of molecules in terms of size, chemistry or the dosage formulation in which it is contained, that may be administered into humans and animals using microneedles is virtually unlimited.

Microneedles are generally fabricated in arrays, synthesised using etching techniques, such as chemical or physical etching and standard lithographic procedures. The materials used range from silicon to polymers such as PDMS. They generally measure tens of microns to hundreds of microns in length and varying tip diameters, usually less than 10 microns.

Henry et. al demonstrated that application of microneedles on the human skin for 10 seconds resulted in a 1000 fold increase in permeability of the skin to calcein. However upon removal of the microneedle array there was a 10,000 fold increase in permeation. i.e., drug was able to permeate much more readily through the holes/microchannels created by the mironeedles. Similarly, the microneedles may be utilised as a conduit for the delivery of drugs through the skin for systemic effect with rapid onset.

The delivery of vaccines requires a strong immune response to optimise the effect of the drug, and such response is generally achieved through the use of adjuvants designed to boost the immune response. The skin is a major immunological organ with antigen presenting Langerhan cells in rich supply, covering almost 15% of the surface area of the skin. Vaccines delivered by the transdermal route are taken up by these Langerhans cells and migrate to the Lymph nodes where antigen specific immunity is activated. Microneedles therefore provide a highly efficient means for administering vaccines.

Mechanism of Skin Penetration

The mechanics of microneedle insertion into the skin is critical to its practical application. Needles with the correct geometry and strength/physical properties are able to penetrate the skin, provided the penetration force is less than the breaking force of the needle/tip.

The optimum needle types are those with a small tip radius and high wall thickness. Penetration depth is also dictated by needle diameter, inter-needle spacing, and length. In addition to the design and geometry of the needles due consideration must be given to the method by which the microneedles are applied to the skin, to ensure the requisite depth of penetration occurs, and such that drug permeation is predictable and not erratic. It can be expected that those needle arrays whereby drug is pumped through the bore into the skin are likely to produce better defined drug plasma concentrations, compared to those where the function of the microneedle is to create cavities in the skin followed by drug permeation through these cavities.

Microneedles have strong potential for the transdermal delivery of a very wide range of drugs and therapeutic agents, for both immediate effect and potentially for sustained action through appropriate formulation enhancements.

Key features of Nemaura’s Microneedle system

• Pain free drug delivery
• Operator independent robust and reproducible delivery
• Backflow prevented/minimised
• Timed control possible
• Diagnostic capability
• Sustained delivery or bolus dose administration

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Registered Name: Nemaura Pharma Limited
Country of Registration: England and Wales
Registered Office: Holywell Park, Loughborough, LE11 3AQ, United Kingdom
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