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2016, N4, pp. 04-16

V.N. Bagratashvili, S.E. Bogorodskiy, A.M. Egorov, L.I. Krotova, A.V. Mironov, O.O. Parenago, O.I. Pokrovskiy, K.B. Ustinovich, P.S. Chizhov, D.I. Prokopchuk, V.K. Popov, S.I. Tsypina

Risperidone Polymorphism in SCF Proccesses of Mironization and Encapsulation into Aliphatic Polyesters

Polymorph transformations of risperidone during its micronization and encapsulation into aliphatic polyesters (polylactide and polylactoglycolide) using supercritical carbon dioxide were studied. It was shown that during SAS (Supercritical Anti-Solvent) and RESS (Rapid Expansion of Supercritical Solutions) micronization of risperidone, which initially had polymorphic form A it crystallized into a less thermodynamically stable form B. In case of SAS method, this transition is complete; in case of RESS, it is partial. During PGSS (Particles from Gas Saturated Solutions), encapsulation of micronized B-form into polylactides or polylactoglycolides as well as during monolythization with subsequent cryomilling (MSC) B-risperidone partially turns back into A-form. Whereas MSC-micronization of initial -risperidone with its subsequent PGSS or MSC encapsulation into polylactides or polylactoglycolides does not cause any change in polymorph state of this substance, it remains in -form.

Key words: crystal polymorphism, risperidone, SCF-micronization, SCFincapsulation, rapid expansion of supercritical solutions, supercritical antisolvent preci pitation, particles from gas saturated solutions

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