[Comparative toxicity of oxytetracycline and its semisynthetic derivatives, methacycline and doxycycline].

The acute toxicity parameters of oxytetracycline and its semisynthetic derivatives was determined on laboratory animals of various species. The three antibiotics were described as belonging to the group of low toxic compounds according to the classification adopted in industrial toxicology. However, the absolute values of LD50 indicated that doxycycline was 5.6 or 2.8 times more toxic than oxyteyracycline or methacycline respectively. In addition, doxycycline had the most pronounced hepatoxic effect.