3D Printing of solid pharmaceutical formulations
Three-dimensional printing (3DP) has been widely used to produce customisable dosage forms useful for adherence to personalised medical therapies [1]. 3DP is a process in which a 3D object is constructed by building successive layers of material on top of each other. In order to achieve high geometric variation and significant dosage flexibility, the digital file, containing the information of the object to be printed, can be easily modified in real-time to design formulations that meet patients' needs. This enables the development of precision medicine, based on the concept of “made-to-measure” production for each individual patient. Another important advantage of 3DP over traditional production systems is the realisation of greater product structural complexity, enabling the development of polypills for polypharmacy. In addition, 3DP offers the possibility of accelerating production times, with a significant reduction in costs due to less material waste and the possibility of bypassing certain production steps [2]. According to the American Society for Testing and Materials (ASTM), the printing techniques used to date can be classified into seven different categories. Of these, material extrusion (ME) is the most frequently used in the pharmaceutical sector, in particular, to produce customised medicines. 3D ME includes Fused Deposition Modelling (FDM) and Direct Powder Extrusion (DPE) techniques [3]. DPE represents one of the most innovative 3DP techniques with the most promising applicability in the pharmaceutical field. It enables the production of finished solid pharmaceutical forms in a single step, directly from mixtures of excipients and active pharmaceutical ingredients. Thus, DPE represents an evolution of the more widely used FDM, which requires the use of thermoplastic filaments as raw material. The elimination of the filament production step, which is carried out by Hot Melt Extrusion (HME), extends the choice of active ingredients and excipients, reducing their risk of degradation due to less exposure to thermal stress. Thus, DPE offers clear advantages over the multistep FDM technique, facilitating the production of customised pharmaceutical forms in a single extrusion step [4]. The 3DForMe® printer, based on DPE, was developed with the aim of improving the preparation processes of solid pharmaceutical forms realized by 3DP. DPE printing technique has been effectively employed in scientific research to develop new solid pharmaceutical formulations presenting improved physical-chemical characteristics that are presented in this presentation in four different case studies on drugs belonging to classes II and IV according to the Biopharmaceutical Classification System (BCS) [6-7].
REFERENCES
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