Application of near-infrared spectroscopy in detecting residual crystallinity in carbamazepine – Soluplus® solid dispersions prepared with solvent casting and hot-melt extrusion

Amorphous solid dispersions can improve the solubility and dissolution rate of poorly soluble drugs. However, residual crystallinity can adversely affect the dissolution in formulations design to be in amorphous state. This study aimed to develop near-infrared spectroscopy (NIRS) as a potential real-time in-line approach to detect residual crystallinity and carbamazepine (CBZ) polymorphs in its Soluplus® dispersions.

Our results show that different CBZ-Soluplus® ratios and processing techniques can affect the polymorphism of CBZ. CBZ Form II and III appeared in 30% and 50% CBZ solvent casting dispersions, respectively, while a mixture of Form I and III was detected in 50% CBZ hot-melt extruded samples. All the solid-state forms of CBZ were confirmed by X-ray diffraction (XRD). Our results showed that NIR was able to detect residual crystalline CBZ and distinguish the CBZ Form III from other polymorphs using the second derivative of the spectra.

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Article information: Hanpin Lim, Dongyue Yu, Stephen W. Hoag, Application of near-infrared spectroscopy in detecting residual crystallinity in carbamazepine – Soluplus® solid dispersions prepared with solvent casting and hot-melt extrusion, Journal of Drug Delivery Science and Technology, 2021. https://doi.org/10.1016/j.jddst.2021.102713.