Extrusion based three dimensional (3D) printing is defined as a process used to make a 3D object layer by layer directly from a computer aided device (CAD). The application of extrusion based 3D printing process to manufacture functional oral solid tablets with relatively complex geometries is demonstrated in this thesis.
In Chapter 3 the viability of using a basic desktop 3D printer (Fab@Home) to print functional guaifenesin bilayer tablets (GBTs) is demonstrated. Guaifenesin is an over the counter (OTC) water soluble medicine used as expectorant for reduction of chest congestion caused by common cold and infections in respiratory system. The bilayer tablets were printed using the standard pharmaceutical excipients; hydroxypropyl methyl cellulose (HPMC) 2208, 2910, sodium starch glycolate (SSG), microcrystalline cellulose (MCC) and polyacrylic acid (PAA) in order mimic the commercial model formulation (Mucinex®) guaifenesin extended-release bilayer tablets. The 3D printed guaifenesin bilayer tablets (GBTs) were evaluated for mechanical properties as a comparison to the commercial GBTs and were found to be within acceptable range as defined by the international standards stated in the USP. Drug releases from the 3D printed GBTs were decreased as the amount of HPMC 2208 increased due to the increased wettability, swelling properties and gel barrier formation of the HPMC. The 3D printed GBTs also showed, as required, two release profiles: immediate release (IR) from the top layer containing disintegrants; SSG and MCC and sustained release (SR) profile from the lower layer containing HPMC 2208. The kinetic drug release data from the 3D printed and commercial GBTs were best modelled using the Korsmeyer–Peppas model with n values between 0.27 and 0.44. This suggests Fickian diffusion drug release through a hydrated HPMC gel layer. Other physical characterisations: X-Ray Powder Diffraction (XRPD), Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), and Differential Scanning Calorimetry (DSC) showed that there was no detectable interaction between guaifenesin and the used excipients in both 3D printed and commercial GBTs.