Study on the preparation of antibiotic microparticles by supercritical fluid process

The supercritical fluid assisted atomization process—a novel supercritical fluid technology—was developed for the preparation of microparticles. Microparticles of erythromycin, griseofulvin and tetracycline were precipitated from solvents, comprising of ethanol or acetone, to examine the feasibility of application of this process in the preparation of drug microparticles. The particle morphology, size and size distribution were characterized by scanning electron microscopy and wide-angle X-ray diffraction (WAXD) patterns, and the organic solvent residue was measured by gas chromatography. Results of this study indicate that the process can be operated continuously and demonstrates great potential for application in the micronization of not only lipid-soluble, but also water-soluble, drugs. The three abovementioned antibiotics can be successfully micronized by this process. In comparison with the untreated material, the morphology, size and size distribution of the microparticles produced by supercritical fluid assisted atomization process were observed to vary significantly. Most microparticles are amorphous, with a narrow size distribution of 0.5–2 µm. The organic solvent residue is in these microparticles was markedly less than the standard value in the Chinese pharmacopoeia.