3.8. Pharmaceutical Characterization of 3D Printed Tablets

With the aim of assessing weight uniformity, six tablets were arbitrarily chosen for each formulation and weighed by operating high-precision digital balance (Ohaus^® Analytical Plus balance, resolution 0.01 mg). The average mass was calculated, and the standard deviation was determined for both preparations.

The influence of the channeled design on the mechanical properties of the FDM 3D printed tablets was assessed by employing a crushing strength tester (PTB 111 E, Pharma Test, Hainburg, Germany). Then, five tablets were randomly selected from each formulation. Measurements were carried out by positioning the long axis of the dosage form on the trajectory of the applied force.

The disintegration behavior of the channeled tablets was investigated by employing a QC-21 Hanson disintegration examining equipment (Hanson Research, Chatsworth, CA, USA). Then, two tablets from each formulation were arbitrarily chosen and the units were individually positioned into a compartment of the basket rack assembly, which was submerged into a beaker that contained distilled water maintained at 37 °C. The conclusive moment of the disintegration process for each dosage form was considered the point when no visible tablet fragments were detected in the mesh.

In vitro drug release studies of the 3D printed tablets with a drug content of ~245 mg were carried out on PT-DT70 apparatus (Pharma Test Apparatebau AG, Hainburg, Germany) using USP Type II dissolution model (paddle). Then, two tablets from each formulation were randomly selected to be examined in each dissolution medium. Briefly, the dosage forms were placed in the vessel and stirred (50 rpm) in three different dissolution media (900 mL), at 37 °C, as follows: 0.1 M hydrochloric acid buffer (pH 1.2) for 3 h, phosphate buffer at pH 6.8 for 8 h, and phosphate buffer at pH 7.4 for 8 h. Samples (5 mL) were withdrawn from the dissolution medium at preset time points (5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 40 min, 50 min, 60 min, 90 min, 120 min, 180 min, 300 min, 480 min) and replaced with fresh medium, then were filtered via 10 µm cannula filters and assayed using UV-VIS spectrophotometer (Specord^®200 Plus, AnalytikJena, Jena, Germany) at 255 nm wavelength.