In what have been considered to become painless alternatives for injections, researchers at the University of Texas at Dallas in the United States have 3D printed polymer microneedle arrays which are able to deliver drugs simply through a patch that can be applied to the skin.
What are Microneedles?
Microneedles are tiny needles that can be characterised as solid, coated, dissolving and hollow depending on their method of drug delivery to the skin. These needles are mostly used when delivering low molecular weight drugs. Polymer microneedles are type of dissolving microneedles that encapsulate drugs and fully dissolve into the skin.
Lately, microneedles have gathered increased attention in the field of medicine because of the ease they offer to unskilled carers and even patients to deliver drugs safely and with minimal risk of infection in comparison with traditional transdermal injections, which require special training. In addition, these microneedles also have an extended shelf-life than drugs stored as injectable liquids.
However, manufacturing microneedles with right dimensions is a difficult task and can be a costly affair because these needles are made with the difficult to reproduce reusable templates and expensive photolithography equipment.
This is where the researchers took help of 3D printing and manufactured the needles using fused deposition modeling (FDM) technique. The researchers used a 3D modeling software to create needles of various shapes and 3D printed them rapidly with custom size using polylactic acid. Polylactic acid is an FDA approved renewable biodegradable thermoplastic material. The researchers used this material to load drugs and tested it on animal models (pig skin).
Below is a schematic illustration of how the microneedles were created using a combination of FDM and a post-fabrication etching protocol used by the researchers.
The results which were published in ChemRxiv revealed that 3D printed microneedles effectively penetrated the skin up to the levels necessary for drug delivery. For example, the researchers showed that the 3D printed microneedles were able to penetrate stratum corneum – the outermost layer of the skin. This feature of the microneedles is considered to be effective in delivering drugs when compared with conventional transdermal techniques whose drug delivery is limited by the barrier properties of the stratum corneum.
The use of 3D printing as a novel fabrication method for these microneedles will now make it possible to prototype microneedles at a relatively lower costs and preferably increase the use of microneedles as methods of drug delivery in the future because such needles are simple for patients to apply for delivery of drugs. Alternatively, the use of such microneedles could also improve patient compliance with pharmaceutical drugs especially among patients with needle-phobia.