Influence of the geometry of 3D printed solid oral dosage forms on their swallowability

3D printing can be used to realise a wide variety of geometries of oral dosage forms. In this work, the swallowability of 3D-printed dosage forms with comparable size and different shape using fused deposition modelling (FDM) from isomalt was investigated in a controlled, randomised crossover study design. To produce the required number of dosage forms, a commercial 3D printer was modified with regard to product safety and production time. The modifications carried out permit the printing of 4 pharmaceutical forms simultaneously as well as the printing of rigid filaments. Six 3D-printed placebo objects and two compressed placebo reference objects were tested by 12 subjects in a blinded design. A questionnaire was used to assess swallowability, foreign body sensation at the moment of swallowing, persistent foreign body sensation after swallowing and pain after swallowing. Furthermore, the amount of additional water drunk after administration was documented. With the modified printer, the required 576 test objects could be printed within a few days with good reproducibility. In all questions, the best results were obtained for the printed and compressed oblong tablets, followed by the printed and compressed round tablets, the football and the sphere. The worst results were obtained for the pyramid closely followed by the cuboctahedron. The study shows that the variety of shapes of oral dosage forms made possible by 3D printing needs to be tested in swallowability studies, as not every shape is also easy to swallow.