Dissolution screening of drug nanosuspensions using in situ UV–vis spectroscopy

The study assessed the usability of in situ UV-vis spectroscopy for differentiating drug nanosuspensions based on their solubility and dissolution. In situ UV-vis spectroscopy has been applied for dissolution testing of drug nanosuspensions. However, uncertainty in applying the technique arises from the possibility that submicron particles can promote quantification error. To reassess usability, model nanosuspension formulations of itraconazole were produced with particle sizes ranging from 247 to 1168 nm. These formulations were subjected to solubility and dissolution analysis using in situ 2nd derivative UV-vis spectroscopy under non-sink conditions. Results indicated that submicron particles indeed caused errors in the concentration values obtained during dissolution experiments. Nevertheless, the data could be used to rank formulations based on their initial dissolution rate. In conclusion, in situ 2nd derivative UV-vis spectroscopy was found to be usable for dissolution screening of drug nanosuspensions even if excess submicron drug particles were present.