Dissolution tests were performed with a United States Pharmacopeia (USP) dissolution apparatus 2 with the rotational speed set at 50 rpm and the temperature at 37°C. The dissolution medium was 600 mL phosphate buffer solution (pH = 6.8) (Ph. Eur.). Three 1 cm extrudate pieces were weighed and added to the dissolution medium. At set time points between 0 and 180 min, samples of 3 mL were removed, and the medium was replaced with 3 mL fresh buffer solution (37 °C). The amount of dissolved IND was investigated by UV-Vis spectroscopy at these time points. The observed drug release for the P(VP-co-VA) and PVP containing samples with 50wt% drug loading were normalize to 100% drug release, and drug release for samples with 80wt% drug loading were scaled using the same scaling factor. For the P1 and P2 containing samples, no normalization was conducted. The data was evaluated using Origin software.