Oxytetracycline Calcium
C44H46CaN4O18 958.93

2-Naphthacenecarboxamide, 4-(dimethylamino)-1,4,4a,5,5a,6,11,12a-octahydro-3,5,6,10,12,12a-hexahydroxy-6-methyl-1,11-dioxo-, calcium salt, [4S-(4,4a,5,5a,6,12a)]-.
4-(Dimethylamino)-1,4,4a,5,5a,6,11,12a-octahydro-3,5,6,10,12,12a-hexahydroxy-6-methyl-1,11-dioxo 2-naphthacenecarboxamide calcium salt [15251-48-6].
» Oxytetracycline Calcium has a potency equivalent to not less than 865 µg of oxytetracycline (C22H24N2O9) per mg, calculated on the anhydrous basis.
Packaging and storage— Preserve in tight, light-resistant containers, and store in a cool place.
Identification— Dissolve a suitable quantity in methanol to obtain a Test Solution containing 1 mg of oxytetracycline per mL, and proceed as directed for Method II under Identification—Tetracyclines 193.
Crystallinity 695: meets the requirements.
pH 791: between 6.0 and 8.0, in an aqueous suspension containing 25 mg per mL.
Water, Method I 921: between 8.0% and 14.0%.
Calcium content— Proceed as directed under Residue on Ignition 281, except to ignite at 550 ± 50 instead of at 800 ± 25: the weight of residue so obtained, multiplied by 0.2944, gives the equivalent of calcium in the Oxytetracycline Calcium taken. The calcium content is between 3.85% and 4.35%, calculated on the anhydrous basis.
Assay— Dissolve an accurately weighed quantity of Oxytetracycline Calcium in an accurately measured volume of 0.1 N hydrochloric acid to obtain a stock solution having a concentration of about 1000 µg of oxytetracycline per mL. Proceed as directed for oxytetracycline under Antibiotics—Microbial 81, using an accurately measured volume of the stock solution diluted quantitatively and stepwise with water to yield a Test Dilution having a concentration assumed to be equal to the median dose level of the Standard.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Ahalya Wise, M.S.
(MDANT05) Monograph Development-Antibiotics
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 3180