Abstract: OBJECTIVE To conduct preformulation study of ketorolac isopropyl ester which is prodrug of ketorolac. METHODS Ketorolac isopropyl ester was synthesized. Quantification method using HPLC-UV was established and validated. Physicochemical properties including solubility, oil/water partition coefficient and degradation kinetics were investigated, followed by revealing drug stability and drug-excipients compatibility under forced degradation experiments. RESULTS Ketorolac isopropyl ester was sparingly soluble in water(52.66 μg·mL^-1) but miscible with oil phase. The LogP value of the prodrug was 3.95±0.03. Analytical method of ketorolac isopropyl ester was established with good linearity, high accuracy(RSD<2%) and high recovery yield(>99.5%). The aqueous stability of ketorolac isopropyl ester was impaired with the increase of pH value and temperature under specific conditions. Fast degradation was found when placing ketorolac isopropyl ester into the medium of rat plasma or liver homogenate solution. For example, the degradation rate constant(k_obs) of the prodrug in 50% rat plasma solution or 20% liver homogenate solution was 0.51 min^-1 and 0.15 min^-1, respectively. Ketorolac isopropyl ester was comparatively stable when presented in the environment with high temperature or high humidity, but it was unstable under the strong light, which was further proved by the drug-excipients stability studies. CONCLUSION The appropriate properties of ketorolac isopropyl ester on solubility, partition coefficient, degradation kinetics, chemical stability and drug-excipients compatibility enabled feasibility on preparation of intravenous lipid emulsion which provide experimental fundament to develop novel ketorolac injectables.