Thermal inkjet application in the preparation of oral dosage forms: dispensing of prednisolone solutions and polymorphic characterization by solid-state spectroscopic techniques.

The utility of thermal inkjet (TIJ) technology for preparing solid dosage forms of drugs was examined. Solutions of prednisolone in a solvent mixture of ethanol, water, and glycerol (80/17/3 by volume) were dispensed onto poly(tetrafluoroethylene)-coated fiberglass films using TIJ cartridges and a personal printer and using a micropipette for comparison. The post-dried, TIJ-dispensed samples were shown to contain a mixture of prednisolone Forms I and III based on PXRD analyses that were confirmed by Raman analyses. The starting commercial material was determined to be Form I. Samples prepared by dispensing the solution from a micropipette initially showed only Form I; subsequent Raman mapping of these samples revealed the presence of two polymorphs. Raman mapping of the TIJ-dispensed samples also showed both polymorphs. The results indicate that the solvent mixture used in the dispensing solution combined with the thermal treatment of the samples after dispensing were likely the primary reason for the generation of the two polymorphs. The advantages of using a multidisciplinary approach to characterize drug delivery systems are demonstrated using solid state mapping techniques. Both PXRD and Raman spectroscopy were needed to fully characterize the samples. Finally, this report clarifies prednisolone's polymorphic nomenclature existent in the scientific literature.