Baramee Chanabodeechalermrung. Design, material selection, and formulation of dissolving microneedles for transdermal drug delivery system. Doctoral Degree(Pharmacy). Chiang Mai University. Library. : Chiang Mai University, 2568.
Design, material selection, and formulation of dissolving microneedles for transdermal drug delivery system
Abstract:
Three-dimensional (3D) printing, an additive manufacturing (AM) technology, serves as an alternative technique for producing 3D-printed microneedles (MNs) patches with high accuracy and resolution by constructing object layer by layer starting from the base. Although 3D printing can print complex structures as desired, some important printing parameters, such as curing time, angle of printing, and anti-aliasing (AA) need to be evaluated to obtain a complete 3D-printed MNs patch. Moreover, the fabricated 3D-printed MN patches can be employed to manufacture polydimethylsiloxane (PDMS) MN molds, which are then used for dissolving microneedles (DMNs) fabrication. However, in DMN production, polymers must dissolve upon contact with biological fluids and release the active pharmaceutical ingredients. Thus, this study aims to explore the suitable printing parameters for 3D-printed MN patch fabrication, produce MN mold and DMNs, and evaluate the ability to dissolve and release active drug of DMNs. Before evaluating the optimal printing parameters, AUTODESK® FUSION 360TM Software, a computer-aided design (CAD) tool, was used to design four distinct shapes of MNs: pyramid mounted over a long cube (shape A), cone mounted over a cylinder (shape B), pyramidal shape (shape C), and conical shape (shape D) with compensated bases of 350, 450 and 550 µm. The four shapes with a 350 µm base were printed utilizing acrylic-based resin with stereolithography (SLA) 3D printer to determine the optimal printing parameters for each shape. The results illustrated that the suitable curing time and printing angle of square base (shape A and C), were 1.5 s and 30o while for round base (shape B and D), they were 2.0 s and 45o, respectively and all four shapes required AA to eliminate stair-stepped edges on the MN surfaces. Furthermore, these obtained parameters were applied to produce MNs with the base of 450 and 550 µm. All twelve 3D-printed patches were successfully used to manufacture PDMS MN molds, which were then employed to fabricate hydroxypropyl methylcellulose (HPMC ; H) and polyvinyl pyrrolidone (PVP ; P) K90 DMNs. As a result, shape A and B demonstrated superior physicochemical properties compared to shape C and D. Moreover, shape A and B with the base of 550 µm (sample 9 and 10) exhibited a complete needle shape, including minimal height reduction (<10%) and approximately 100% of blue dots. Previous experiments have highlighted that 3D printing can be successfully employed to manufacture custom 3D-printed MN patches. In this study, the needle was designed using Fusion 360 software in a pyramid mounted over a long cube shape with the base of 450 µm and the height of 900 µm before being printed using acrylic-based resin and SLA 3D printer. The 3D-printed patches were then utilized to construct PDMS molds, which were used for HPMC/PVP K90 DMN fabrication with and without lidocaine (L). The study examined needle appearance, mechanical properties, insertion ability, dissolving behavior, drug-loading content, and drug release. As a result, H51P2- L, H501P2-L, and H901P2-L exhibited complete needle appearance with low percentage of height change (< 10%), high percentage of blue-dot (> 80%), approximately 100% of drug loading capacity, fast dissolution upon contact with phosphate buffered saline (PBS) solution pH 7.4, successful release of lidocaine HCl within 1 hour, including no chemical interactions between HPMC, PVP, and lidocaine HCl, confirmed via Fourier transform infrared (FTIR) analysis. These findings revealed that 3D printing is a viable method for constructing MN patches employed for producing MN molds, which were utilized for fabricating DMNs, using them as a promising approach for transdermal drug delivery systems