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metacycline

alt. A tetracycline antibiotic used as a precursor in the industrial synthesis of doxycycline. n. A tetracycline antibiotic used as a precursor in the industrial synthesis of doxycycline.

Wikipedia
Metacycline

Metacycline is a tetracycline antibiotic. It is used as a precursor in the industrial synthesis of doxycycline hyclate. It should not be confused with the antibiotic methicillin (aka meticillin).