Abstract
Amorphous 16-membered macrolide compounds were prepared by spray drying, and the physicochemical stability of the amorphous states has been investigated. Josamycin, rokitamycin, midecamycin, 3-O-acetyl-4"-O-isovaleryltylosin, miocamycin and 4"-O-(4-methoxyphenyl)acetyltylosin were used as macrolide compounds. From X-ray powder diffractometry and differential scanning calorimetric (DSC) measurements, all the spray dried compounds were recognized to be in a glassy state. Miocamycin and 4"-O-(4-methoxyphenyl)acetyltylosin glasses showed crystallization and fusion peaks on DSC thermograms, and were crystallized after 6 months of storage at 313 K and 75% relative humidity. Other compounds showed only a glass transition peak on each DSC thermogram, and the glassy state was maintained stably against humidity. It was found that the physicochemical stability of the glassy state of miocamycin was closely related to the inlet temperature of the spray drying process.
