Polymorphism of Risperidone in Supercritical Fluid Processes of Micronization and Encapsulation into Aliphatic Polyesters

• Published in: Russian journal of physical chemistry. B Vol. 11; no. 7; pp. 1163 - 1172
• Main Authors: Bagratashvili, V. N., Bogorodskiy, S. E., Egorov, A. M., Krotova, L. I., Mironov, A. V., Parenago, O. O., Pokrovskiy, O. I., Ustinovich, K. B., Chizhov, P. S., Prokopchuk, D. I., Popov, V. K., Tsypina, S. I.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-12-2017; Springer Nature B.V
• Subjects: Aliphatic compounds; Carbon dioxide; Chemical precipitation; Chemistry; Chemistry and Materials Science; Crystallization; Encapsulation; Physical Chemistry; Polyester resins; Polyesters; Polylactic acid; Polymorphism; Supercritical fluids; supercritical antisolvent precipitation; rapid expansion of supercritical solutions; risperidone; SCF encapsulation; gas-saturated solution particles; crystal polymorphs; supercritical fluid (SCF) micronization
• ISSN: 1990-7931; 1990-7923
• DOI: 10.1134/S199079311707003X

The specific features of the transformation of risperidone polymorphs as a result of micronization and encapsulation into aliphatic polyesters (polylactides and polylactoglycolide) have been studied using supercritical (SC) carbon dioxide. It has been shown that the micronization of risperidone, which originally is polymorph A, via the rapid expansion of supercritical solutions (RESS) and the supercritical antisolvent (SAS) precipitation leads to its crystallization in less thermodynamically stable polymorph B. This transition is complete for SAS and only partial for RESS. When these micronized samples are encapsulated into polylactides and polylactoglycolides via the formation of particles from gas-saturated solutions (PGSS) and monolithization with further cryogrinding (MCG), risperidone polymorph B is partially converted back into polymorph A. At the same time, the micronization of initial risperidone polymorph A via cryogrinding and its further PGSS and MCG encapsulation into polylactides or polylactoglycolides does not result in any change in the polymorphic state of risperidone, and it always remains in initial polymorph A.