Transformation under pressure: Discovery of a novel crystalline form of anthelmintic drug Praziquantel using high-pressure supercritical carbon dioxide

Supercritical carbon dioxide (CO2) has been used as a processing technique to control polymorphism of pharmaceuticals. However, there are fewer reports of novel polymorphs being discovered by supercritical CO2 processing. As supercritical crystallization methods gain attention for potential in pharmaceutical processing, they may become a critical screening tool for discovery of new polymorphs. In this work, a case study is presented for a novel crystalline form of the anthelmintic drug, Praziquantel, found through supercritical CO2 processing. The novel form of Praziquantel was characterized by chromatography, nuclear magnetic resonance and infrared spectroscopy, X-ray powder diffraction, thermal analysis, and scanning electron microscopy. Furthermore, the novel form exhibited 13-20% improved solubility compared to commercial Form A between pH 1.6 and 7.5 and was physically stable under stressed conditions (40 degrees C and 75% relative humidity) for 7.5 weeks. Overall, this work showed that supercritical CO2 processing is a valuable tool to screen for novel, and possibly viable polymorphs of pharmaceutical compounds with improved properties.

Automated summary

This study presents a novel crystalline form of the anthelmintic drug Praziquantel discovered through supercritical CO2 processing. The novel form was characterized and tested for its properties, showing improved solubility and physical stability compared to the commercial form. These findings highlight the value of supercritical CO2 processing as a tool for identifying new polymorphs with enhanced properties.