6-epi Doxycycline
6-Epi-doxycycline is the C-6 epimer of Doxycycline (HY-N0565), formed as a degradation impurity through epimerization of Doxycycline under abnormal conditions (e.g., high temperature, pH changes, or humidity). 6-Epi-doxycycline is commonly used for the detection and analysis of impurity levels in pharmaceutical formulations.