metha·cy·cline .meth-ə-'sī-.klēn n a semisynthetic tetracycline C22H22N2O8 with longer duration of action than most other tetracyclines and used in the treatment of gonorrhea esp. in penicillin-sensitive subjects
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meth·a·cy·cline (meth″ə-siґklēn) a semisynthetic broad-spectrum antibiotic of the tetracycline group.Medical dictionary. 2011.