Multiple variable effects in the customisation of fused deposition modelling 3D-printed medicines: A design of experiments (DoE) approach

Fused deposition modelling (FDM) is the most explored three-dimensional (3D) printing technique in pharmaceutics. However, there is still a lack of knowledge about the factors influencing the properties of the printed forms. Here, the main and combined effects of the presence of a pore former (mannitol, 0% or 10%), the infill percentage (50% or 100%) and the drug percentage (5% or 10%) on the pharmaceutical properties of 3D-printed forms were evaluated by a design of experiments (DoE) approach. Poly(Ɛ-caprolactone) filaments were produced by hot-melt extrusion and dexamethasone was used as a hydrophobic model drug. The 23 factorial design afforded eight formulations printed at 105 °C. The drug content ranged from 9.87 to 25.59 mg/unit, depending on the drug and infill percentages. The drug release profiles followed the Higuchi model. The infill percentage modulated the drug release rate, whereas the pore former had a combined effect on this parameter, depending on the drug and infill percentage levels. According to the DoE data, besides the changes in the infill percentage, the addition of a pore former can also tailor the drug release rate from 3D-printed solid forms. These findings may assist the development of personalised tumour implants by 3D printing.