Additive manufacturing offers the advantage of infinite freedom to design and fabricate complex parts at reduced lead-time. However, the surface quality of additively manufactured parts remains well behind the conventionally processed counterparts. This paper aims to systematically investigate the impact of varying surface inclination angles with respect to the build direction on the resultant surface textures. A bespoke metal truncheon artifact with inclination angles varying from 0 deg to 180 deg was built by selective laser melting. Focus variation microscopy was used to measure the topography of inclined surfaces with a tilt angle of up to 132 deg. The measurement data were then analyzed to characterize the staircase effect and the particles adherent to the artifact surface. Areal surface texture parameters, including height parameters, spatial parameters, functional parameters, and feature parameters, were explored to quantify the general surface topography, the staircase effect, and the particle features. The areal surface texture characterization and particle analysis reveal the resulted surface topographies are strongly correlated with the surface inclination angles.

Overactive bladder (OAB) is a symptomatic complex condition characterised by frequent urinary urgency, nocturia, and urinary incontinence with or without urgency. Gabapentin is an effective treatment for OAB, but its narrow absorption window is a concern, as it is preferentially absorbed from the upper small intestine, resulting in poor bioavailability. We aimed to develop an extended release, intragastric floating system to overcome this drawback. For this purpose, plasticiser-free filaments of PEO (polyethylene oxide) and the drug (gabapentin) were developed using hot melt extrusion. The filaments were extruded successfully with 98% drug loading, possessed good mechanical properties, and successfully produced printed tablets using fused deposition modelling (FDM). Tablets were printed with varying shell numbers and infill density to investigate their floating capacity. Among the seven matrix tablet formulations, F2 (2 shells, 0% infill) showed the highest floating time, i.e., more than 10 h. The drug release rates fell as the infill density and shell number increased. However, F2 was the best performing formulation in terms of floating and release and was chosen for in vivo (pharmacokinetic) studies. The pharmacokinetic findings exhibit improved gabapentin absorption compared to the control (oral solution). Overall, it can be concluded that 3D printing technology is an easy-to-use approach which demonstrated its benefits in developing medicines based on a mucoadhesive gastroretentive strategy, improving the absorption of gabapentin with potential for the improved management of OAB.