Preparation of uniform prednisolone microcrystals by a controlled microprecipitation method

Prednisolone (PDL) microcrystals were successfully prepared by a controlled microprecipitation method. The characterization of PDL microcrystals by SEM and PSD indicated that the hexagonal and tetragonal PDL microcrystals with an average particle size of 1.60 and 1.46 μm could be prepared under a stirring speed of 10,000 rpm at 14 and 4 °C, respectively. The morphology and the particle size of PDL could be well controlled, from 1.60 to 6.12 μm for hexagonal microcrystals and 1.46 to 3.90 μm for tetragonal ones, by altering the operating parameters such as temperature, stirring speed and stabilizers. The XRD, TGA–DSC, FT-IR and physical stability studies demonstrated that the as-prepared hexagonal and tetragonal PDL microcrystals with the same pseudopolymorphic form were much more stable in water than the commercial micronized PDL with another crystal form. The dissolution tests showed that the hexagonal and tetragonal PDL microcrystals exhibited significantly enhanced dissolution property when compared to commercial micronized PDL.