3D printing by fused deposition modeling of single- and multi-compartment hollow systems for oral delivery – A review

Feasibility of fused deposition modeling in 3D printing of hollow systems intended to convey different formulations for oral administration has recently been investigated. A major advantage of such printed devices is represented by the possibility of separately undertaking the development of the inner core from that of the outer shell, which could also act as a release-controlling barrier. Systems either composed of parts to be filled and assembled after fabrication or fabricated and filled in a single manufacturing process represent the main focus of this review. Devices having relatively simple (e.g. single-compartment capsule-like) configuration were first proposed followed by systems entailing multiple inner compartments. The latter were meant to be filled with different formulations, left empty for ensuring floatation or achieve combined release kinetics. For each of the reviewed systems, design, formulation approaches, manufacturing as well as release performance obtained were critically described. Versatility of FDM, especially in terms of geometric freedom provided, was highlighted together with some limitations that still need to be addressed, as expected for a newly-adopted fabrication technique that holds potential for being implemented in the pharmaceutical field.