β-Apooxytetracycline is a potential impurity found in commercial preparations of oxytetracycline. β-Apooxytetracycline is a degradation product formed from oxytetracycline via acid hydrolysis. It has a relative potency of 0.1 compared with oxytetracycline for inhibiting the growth of aerobic sludge bacteria, an MIC50 value of 32 mg/L for tetracycline-sensitive strains of Pseudomonas, and MIC50 values of greater than 32 mg/L for tetracycline-sensitive strains of Agrobacterium, Moraxella, and Bacillus, as well as tetracycline-resistant strains of E. coli. β-Apooxytetracycline (10 mg/kg) is toxic to rats, decreasing body weight, disrupting blood cell counts, and inducing hepatocyte necrosis.