Scanning probe microscopy method for nanosuspension stabilizer selection.

An atomic force microscopy (AFM) method was successfully developed and utilized for investigating the interaction of polymeric stabilizers with ibuprofen to determine their suitability for the preparation and stabilization of ibuprofen nanosuspensions. Images obtained clearly showed that HPMC and HPC interacted strongly with the ibuprofen resulting in extensive surface adsorption, confirming their suitability for ibuprofen nanosuspension preparation. In addition, differences in the morphology of the adsorbed HPMC and HPC molecules were observed, which may be attributed to their variable degree of substitution. Consistent with their poor performance in stabilizing the ibuprofen nanosuspensions, images obtained with PVP and Poloxamer's depicted inadequate adsorption on the ibuprofen surface. Careful analysis of the AFM images and the ibuprofen crystal structure gave valuable insight into the success of top-down processing for the preparation of nanosuspensions as compared to bottom-up processing. On the basis of the relationship observed between nanosuspension stability and adsorption characteristics of specific polymers, such AFM studies can aid in the selection of suitable nanosuspension stabilizers. This method provides the basis for a scientific rationale for nanosuspension stabilizer selection rather than the trial and error method which is currently practiced.