Detecting and Identifying the Complexation of Nimodipine with Hydroxypropyl-β-Cyclodextrin Present in Tablets by Raman Spectroscopy

For CD-based formulations, it is important to directly monitor the complexation status of the drug present in final dosage form pharmaceuticals. In this work, Raman spectroscopy was explored for the detection and identification of the Nimodipine/hydroxypropyl-β-cyclodextrin (NMD/HPβCD) complexation present in the tablet. The evident, consistent Raman spectral changes in the shift, height ratio and area ratio for the characteristic bands of NMD molecule were featured in the NMD/HPβCD complex, and employed to distinguish between complexed and uncomplexed NMD in tablets. A number of practical issues for the Raman measurements performed on the tablets were considered and addressed. The Raman approach and dissolution test were applied to different tablets prepared experimentally at variable granulations. The results demonstrated that the Raman approach can serve as a promising methodology for tablet identification on the complexation. Wet granulation facilitated the process-induced transformations in the complexation. The adequate ethanol in the granulating fluid appeared optimized for the complexation of the two components. The spectral characteristics for dissociation in the tablets were in full accordance with the observations of their diminished initial dissolution parameters. It implied the possibility that the tablet dissolution can be predicted from the Raman interpretation