Nanosuspensions of novel deuterated pyrazoloquinolinones ligand (DK-I-56-1): lyophilization procedure development through cryoprotectant selection and stability study

Abstract

Despite of good pharmacodynamics of DK-I-56-1, novel deuterated pyrazoloquinolinones ligand, low solubility limits its administration. Nanosuspensions can help to overcome this problem, but its small particle size usually leads to particle agglomeration in short period of time. This phenomenon can be prevented by performing lyophilization. In this study cryoprotectants selection as well as characterization (particle size measurements after redispersion, scanning electron microscopy, differential scanning calorimetry and thermogravimetric measurements) of obtained freeze dried preparations was carried out. It was observed that sucrose/mannitol ratio 1:1 and 3:2 in total concentration of 10% can preserve particle size during lyophilization. However, after stability study conducted during one month storage at 25 °C and 40 °C, particle size remained in submicron range only in one sample. Changes in particle size were also followed by changes in polymorphic form of mannitol. It can be concluded that changes of crystal forms in freeze dried preparations during storage could jeopardize their stability, and therefore should be carefully examined.