Packaging and storage— Preserve in well-closed containers.

Labeling— Tablets that are gelatin-coated are so labeled.

Identification—

Disintegration 701: 10 minutes, except that where Tablets are labeled as gelatin-coated the time is 30 minutes, simulated gastric fluid TS being substituted for water in the test.

Uniformity of dosage units 905: meet the requirements for Weight Variation with respect to calcium carbonate and to magnesium carbonate.

Acid-neutralizing capacity 301— Not less than 5 mEq of acid is consumed by the minimum single dose recommended in the labeling, and not less than the number of mEq calculated by the formula: in which 0.024 and 0.02 are the theoretical acid-neutralizing capacities, in mEq, of MgCO3 and CaCO3, respectively; and M and C are the respective quantities, in mg, of MgCO3 and CaCO3 in the specimen tested, based on the labeled quantities.

Assay for calcium carbonate— Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 400 mg of calcium carbonate, to a beaker with the aid of 25 mL of water, and add 10 mL of 1 N hydrochloric acid. Heat on a steam bath for 30 minutes, allow to cool, transfer with the aid of water to a 100-mL volumetric flask, dilute with water to volume, mix, and filter. Transfer 20.0 mL of the filtrate to a suitable container, dilute with water to 100 mL, add 15 mL of 1 N sodium hydroxide, 5 mL of triethanolamine, and 100 mg of hydroxy naphthol blue, and titrate with 0.05 M edetate disodium VS until the solution is deep blue. Each mL of 0.05 M edetate disodium is equivalent to 5.004 mg of calcium carbonate (CaCO3).

Assay for magnesium carbonate— Transfer an accurately measured portion of the filtrate remaining from the Assay for calcium carbonate, equivalent to about 120 mg of calcium carbonate and magnesium carbonate combined, to a suitable container, dilute with water to 100 mL, add 10 mL of ammonia–ammonium chloride buffer TS, 5 mL of triethanolamine, and 0.3 mL of eriochrome black TS, and titrate with 0.05 M edetate disodium VS to a blue endpoint. From the volume of 0.05 M edetate disodium consumed, deduct the volume of 0.05 M edetate disodium corresponding to the content of calcium carbonate in the volume of the filtrate taken for the assay. The difference is the volume of 0.05 M edetate disodium equivalent to the amount of magnesium carbonate present. Each mL of 0.05 M edetate disodium is equivalent to 4.216 mg of MgCO3.

Topic/Question	Contact	Expert Committee
Monograph	Elena Gonikberg, Ph.D. Senior Scientist 1-301-816-8251	(MDGRE05) Monograph Development-Gastrointestinal Renal and Endocrine
701	Margareth R.C. Marques, Ph.D. Senior Scientist 1-301-816-8106	(BPC05) Biopharmaceutics05

USP32–NF27 Page 1761