Methacycline, a new tetracycline derivative, published by the study group of Pfizer Institute, U. S. A., is a broad spectrum antibiotic same as well-known tetracycline group antibiotic. How ever, it has 2∼4times antibacterial effect in vivo as compared with that of tetracycline and oxytetracyclite and more prominent effect has also been observed in therapeutic experiment of mouse experimental infectious disease than in tetracycline and oxytetracycline as observed in vitro.
