Development and in vitro evaluation of pH-independent release matrix tablet of weakly acidic drug valsartan using quality by design tools.

The main objective of this study was the development of pH-independent controlled release valsartan matrix tablet in Quality by design (QbD) framework. The quality target product profile (QTPP), critical quality attributes (CQAs) and critical material attributes (CMAs) were defined by science and risk-based methodologies. Potential risk factors were identified with Fishbone diagram. Following, CMAs were further investigated with a semi-quantitative risk assessment method, which has been revised with mitigated risks after development and optimization studies. According to defined critical material attributes, which one of them was determined to be the dissolution, formulation optimization study was performed by using a statistical design of experiment. Formulation variables have been identified and fixed first with a 'One factor at a time (OFAT)' approach. After OFAT studies, a statistical experimental design was conducted with the most critical material attributes. Statistical design space and mathematical prediction equations have been developed for dissolution and hardness, which is important to predict drug dissolution behavior. In conclusion, a pH-independent release has been achieved for weakly acidic drug valsartan with a deeper understanding of drug product quality, with the science and risk-based approaches of QbD tools.