Column chromatography of tetracyclines and their degradation products.

The improved column chromatographic method has been developed for the determination of tetracycline, oxytetracycline N-pyrrolidinemethyltetracycline, methacycline, doxycycline and their degradation products (anhydro and epi forms) in pharmaceutical preparations. The analyses of 13 commercial preparations showed them to contain certain amounts of degradation products. The most contaminated were preparations containing tetracycline and N-pyrrolidinemethyltetracycline. They contain all of degradation products (anhydro and epi forms). Preparations containing oxytetracycline showed the presence of anhydrooxytetracyline but did not contain the epimer. Preparations containing semisynthetic antibiotics, methacycline and doxycycline, showed only the presence of epimers.