Acne is a multifactorial inflammatory skin disease with high prevalence. In this work, the potential of 3D printing to produce flexible personalised-shape anti-acne drug (salicylic acid) loaded devices was demonstrated by two different 3D printing (3DP) technologies: Fused Deposition Modelling (FDM) and stereolithography (SLA). 3D scanning technology was used to obtain a 3D model of a nose adapted to the morphology of an individual. In FDM 3DP, commercially produced Flex EcoPLA™ (FPLA) and polycaprolactone (PCL) filaments were loaded with salicylic acid by hot melt extrusion (HME) (theoretical drug loading - 2% w/w) and used as feedstock material for 3D printing. Drug loading in the FPLA-salicylic acid and PCL-salicylic acid 3D printed patches was 0.4% w/w and 1.2% w/w respectively, indicating significant thermal degradation of drug during HME and 3D printing. Diffusion testing in Franz cells using a synthetic membrane revealed that the drug loaded printed samples released <187μg/cm(2) within 3h. FPLA-salicylic acid filament was successfully printed as a nose-shape mask by FDM 3DP, but the PCL-salicylic acid filament was not. In the SLA printing process, the drug was dissolved in different mixtures of poly(ethylene glycol) diacrylate (PEGDA) and poly(ethylene glycol) (PEG) that were solidified by the action of a laser beam. SLA printing led to 3D printed devices (nose-shape) with higher resolution and higher drug loading (1.9% w/w) than FDM, with no drug degradation. The results of drug diffusion tests revealed that drug diffusion was faster than with the FDM devices, 229 and 291μg/cm(2) within 3h for the two formulations evaluated. In this study, SLA printing was the more appropriate 3D printing technology to manufacture anti-acne devices with salicylic acid. The combination of 3D scanning and 3D printing has the potential to offer solutions to produce personalised drug loaded devices, adapted in shape and size to individual patients.

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trademark of the company Aprecia Pharmaceuticals, LLC., Ohio, USA. Recently, Triastek has received Investigational New Drug (IND) approval from the US FDA for T19, their first 3D printed drug product designed to treat rheumatoid arthritis. [13] As a result of this approval, research into 3D printing for drug delivery has continued to rapidly expand, with several commercially available 3D printers emerging. [14][15][16][17][18][19] More recently, 3D printing has shown its promising potential in the mass production of face masks and face shields in the middle of the 2020 global pandemic when these items were in high demand for protecting healthcare professionals in the fight against COVID-19. [20,21] Generally, the fabrication of complex structures by 3D printing involves the creation of a prototype in computer-aided design (CAD) software, which is subsequently exported as a standard tessellation language (STL) file and sent to the 3D printer. [16,22] The 3D printer's software divides the 3D model data into consecutive 2D slices to facilitate the fabrication of each structure in a layerby-layer manner. Additionally, 3D scanners can also be used to record objects or body parts in the form of digital 3D images. [23] Likewise, X-rays, magnetic resonance imaging (MRI) and computerized tomography (CT) scans produce 2D radiographic images that can be converted to digital 3D model files for the fabrication of personalized anatomical structures. [1,2,6,[24][25][26][27][28] In recent years, the use of 3D printing technology to produce tailor-shaped MNs has gained great attention. MNs are a noninvasive device consisting of multiple micron-sized needles on a single patch, ranging most commonly in height from 25 to 2000 µm. [29] Upon skin insertion, MNs create temporary microscopic channels in the epidermis to either deliver drug molecules via diffusion into the microcirculation or to collect interstitial fluid (ISF) for disease diagnosis and monitoring. [30][31][32][33] As a drug delivery platform, MNs combine the patient-friendly benefits of a transdermal patch with the potential delivery capabilities of a hypodermic injection. The unique attribute of MNs is that they are strong enough to penetrate the resilient skin barrier, the stratum corneum (SC), sufficiently to enable access to the skin's rich microcirculation, yet are short and narrow enough to avoid stimulation with nerve fibers or puncture blood vessels that primarily reside in the dermal layer. Painless application is thus considered the principal benefit of MNs. [34][35][36] Microneedles (MNs) are minimally invasive devices, which have gained extensive interest over the past decades in various fields including drug delivery, disease diagnosis, monitoring, and cosmetics. MN geometry and shape are key parameters that dictate performance and therapeutic efficacy, however, traditional fabrication methods, such as molding, may not be able to offer rapid design modifications. In this regard, the fabrication of MNs using 3D printing technology enables the rapid creation ...

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