| 摘要 |
PROBLEM TO BE SOLVED: To provide a minocycline base having an impurity of 4-epi-minocycline controlled to an extremely low level and having a form more stable than that of a minocycline base known in only an amorphous form.SOLUTION: Provided is the method for manufacturing a minocycline base having three kinds of crystal polymorphic form named as a form I, a form II and a form III characterized by XRD and IR data, and new polymorphic forms thereof. For example, in the form I, a crystalline minocycline is manufactured by dissolving and/or suspending amorphous minocycline salt into an organic solvent selected from ether, such as methyl tert-butyl ether and forming a crystal from the mixture. |
