13-substituted methacycline compounds, methods of treating tetracycline responsive states, and pharmaceutical compositions containing the 13-substituted methacycline compounds are described.

i residui di methacycline 13-substituted, metodi di trattare la tetraciclina sensibli a reagire dichiara e le composizioni farmaceutiche che contengono i residui di methacycline 13-substituted sono descritte.