Key words: SCF-micronization, RESS, levofloxacin hemihydrate, levofloxacin monohydrate, trifluoromethane
Micronization of levofloxacin hemihydate drug substance (LFC) by RESS using trifluoromethane (CHF3) as a polar supercritical solvent was investigated. By scanning electron microscopy, it was shown that at CHF3 temperature of 50°C, micronized LFC particles have the form of submicron-sized microbeads. At a temperature of 100°C, the particles take the form of thin (less than 0.1 microns) elongated plates with rounded edges. At this temperature, an increase in CHF3 pressure from 20 MPa to 35 MPa increases
the average particle size of these particles from 1 to 2 um, respectively. X-ray phase analysis of samples obtained at 50 °C showed the identity of the original and micronized LFC substance corresponding to the structure of levofloxacin hemihydrate — С36Н40F2N6O8⋅H2O. At the same time, it was shown that an increase in the process temperature to 100°C leads to the appearance of one of its polymorphic forms, levofloxacin monohydrate С18Н20F2N3O4⋅H2O in the micronized LFC.
doi:10.34984/SCFTP.2023.18.2.003