» Sterile Erythromycin Lactobionate has a potency equivalent to not less than 525 µg of erythromycin (C₃₇H₆₇NO₁₃) per mg, calculated on the anhydrous basis. In addition, where packaged for dispensing, it contains the equivalent of not less than 90.0 percent and not more than 120.0 percent of the labeled amount of erythromycin (C₃₇H₆₇NO₁₃).