Characterization of prednisolone in controlled porosity osmotic pump pellets using solid-state NMR spectroscopy

The overall objective of this study was to demonstrate the influence of formulation and processing variables on the physical state of prednisolone (PDL) in formulations consisting of PDL, microcrystalline cellulose (MCC), and sulfobutylether-beta-cyclodextrin (CD). PDL was used as a model drug in controlled porosity osmotic pump pellet (CP-OPP) formulations, and was characterized using solid-state NMR spectroscopy and other complimentary analytical techniques. Dosage forms and the solid-state properties of drugs and excipients in a formulation may be influenced by the processing conditions used. Several processing parameters, such as amount of water used in wet granulation and subsequent drying conditions, were found to affect the solid-state transformation of PDL. In addition, the presence of excipients in the CP-OPP was observed to decrease the degree of PDL crystallinity, presumably by creating an inclusion complex with the CD. A hydrated form of PDL was created when PDL was ground with water alone; however, this form was not observed in formulated products. Solid-state NMR spectroscopy was shown to be a powerful technique for the analysis of drug formulations and investigations of the effects of processing conditions.