Usp 2 dissolution test paddle apparatus

The impact of the ratio of polymers used on the release profile of theophylline was assessed using a USP II dissolution test paddle apparatus (Erweka GmbH, Germany). Each experiment was carried out in triplicate at 37 ± 0.5 °C with a paddle speed of 50 rpm. The tablets were tested in 750 mL of 0.1 M HCl (pH 1.2) for 2 h, followed by 4 hrs exposure to pH 6.8 phosphate buffer (through the addition of 250 mL of tribasic phosphate solution 0.215 M). Data was collected each 5 min by an UV/VIS spectrophotometer (PG Instruments Limited, UK) at a wavelength of 272 nm and a path length of 1 mm. Data were analysed using IDISis software version 2012 (Automated Lab, Berkshire, UK).

In vitro disintegration and drug release studies. Tablet disintegration was carried out using an Erweka ZT220 disintegration testing apparatus (Erweka GmbH, Heusenstamm, Germany). Three tablets were randomly selected, weighed and each placed in a basket rack assembly of six cylinders and weights were added on the top of the tablets. The basket rack assembly was then immersed into a beaker containing 0.1M hydrochloric acid at 37 C. The exact time for all tablets to fully leave the mesh was visually noted.
In vitro drug release testing. The impact of the tablet's design on the release pattern of the 3D printed tablets was assessed using a USP II dissolution test paddle apparatus (Erweka GmbH, Germany). The dissolution study was conducted in 900 mL of 0.1 M hydrochloric acid (pH 1.2) at 37 ± 0.5 °C and with paddle speed of 50 rpm. The amount of released theophylline was determined at 5 min intervals by UV/VIS spectrophotometer (PG Instruments Limited, UK) at a wavelength of 272 nm and a path length of 1 mm. Data were analysed using IDISis software version 2012 (Automated Lab, Berkshire, UK).