10.22376/ijpbs.2019.10.1.p1-12 Volume 4 Issue 2 2013 (April - June) The present study describes the development of a comprehensive science and risk based UPLC method and subsequent validation for the simultaneous analysis of related substances of omeprazole and domperidone active pharmaceutical ingredient (API) using a quality by design approach. An efficient experimental design based on systematic scuti ng of all three components of the UPLC method (column temperature, mobile phase A and B) is presented. The optimized UPLC conditions (column temperature of 50°C, mobile phase A organic modifier (buffer: methanol, 900: 50), mobile phase B organic modifier (acetonitrile: methanol, 830: 170)) resulted in fully resolved peaks. The QbD based method development helped in generating a design space and operating space with the knowledge of all method performance characteristics and limitations and successful method robustness within the operating space. P. SRINIVAS, T SIVA RAO, ELAIYALVAR RAMAKRISHNANAND D V GOWDA Quality by design, UPLC, Omeprazole, Domperidone, Design space 906-911