Studies from our laboratory have demonstrated that deflazacort (DEF), a poorly water-soluble glucocorticoid, exhibits a crystalline thermodynamic stable form (DEF-1) and a metastable amorphous phase (DEF-a). Since amorphous forms usually display higher dissolution rates than their crystalline counterparts, their presence in raw powders and pharmaceutical products, by design or accident, can incorporate in them distinct properties; thereby, the importance of characterizing crystalline and amorphous phases. In this study, the disc intrinsic dissolution rates (DIDR) of DEF-1 and DEF-a were determined and compared with corresponding in vivo dissolution rates from compacted pellets in rats, in order to determine if DEF-a had improved the dissolution characteristics of DEF.
The in vitro and in vivo dissolution characteristics of two solid phases of DEF were analyzed. No statistically differences were observed for the in vitro as well as the in vivo dissolution rates of DEF-a and DEF-1, due to DEF-a devitrifies by effect of the applied compaction force. The DIDRs were well reflected in the in vivo dissolution rates of compacted implants.
