Calcium and Magnesium Carbonates Oral Suspension
DEFINITION
Calcium and Magnesium Carbonates Oral Suspension contains NLT 90.0% and NMT 110.0% of the labeled amount of calcium carbonate (CaCO3) and NLT 85.0% and NMT 115.0% of the labeled amount of magnesium carbonate (MgCO3).
IDENTIFICATION
•  A. Identification Tests—General, Calcium 191: The addition of 3 N hydrochloric acid to a quantity of Oral Suspension, equivalent to 500 mg of calcium carbonate, produces effervescence, and the resulting solution, after having been filtered, meets the requirements.
•  B. Identification Tests—General, Magnesium 191
Sample solution:  Heat a quantity of Oral Suspension, equivalent to 800 mg of magnesium carbonate, with 20 mL of 1 N sulfuric acid. Cool, add 20 mL of alcohol, mix, and allow to stand for 30 min. Filter this solution, and add 2 mL of 1 N hydrochloric acid to the filtrate.
Acceptance criteria:  Meets the requirements
ASSAY
•  Calcium Carbonate
Sample solution:  Transfer a portion of Oral Suspension equivalent to 400 mg of calcium carbonate, previously well shaken in its original container and free of air bubbles, to a beaker, with the aid of 20 mL of water, and add 10 mL of 1 N hydrochloric acid. Heat on a steam bath for 30 min, allow to cool, transfer with the aid of water to a 100-mL volumetric flask, dilute with water to volume, filter and use the filtrate. [Note—Reserve a portion of the filtrate for the Sample solution in the Magnesium Carbonate test. ]
Analysis:  Transfer 20.0 mL of Sample solution to a suitable container. Dilute with water to 100 mL, and add 15 mL of 1 N sodium hydroxide, 5 mL of triethanolamine, and 100 mg of hydroxy naphthol blue. 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 CaCO3.
Acceptance criteria:  90.0%–110.0%
•  Magnesium Carbonate
Sample solution:  Use a portion of the filtrate from the Sample solution in the Calcium Carbonate test.
Analysis:  Transfer the Sample solution, equivalent to 120 mg of calcium carbonate and magnesium carbonate combined, to a suitable container. Dilute with water to 100 mL, and add 10 mL of ammonia–ammonium chloride buffer TS, 5 mL of triethanolamine, and 0.3 mL of eriochrome black TS. Titrate with 0.05 M edetate disodium VS to a blue endpoint. From the volume of 0.05 M edetate disodium consumed, subtract the volume of 0.05 M edetate disodium corresponding to the content of calcium carbonate in the portion of the Sample solution taken. The difference is the volume of 0.05 M edetate disodium equivalent to the quantity of magnesium carbonate present. Each mL of 0.05 M edetate disodium is equivalent to 4.216 mg of MgCO3.
Acceptance criteria:  85.0%–115.0%
PERFORMANCE TESTS
•  Deliverable Volume 698: Meets the requirements
SPECIFIC TESTS
•  Microbial Enumeration Tests 61 and Tests for Specified Microorganisms 62: The total aerobic microbial count is NMT 100 cfu/mL, and it meets the requirements of the tests for absence of Escherichia coli and Pseudomonas aeruginosa.
•  pH 791: 7.0–8.6
•  Acid-Neutralizing Capacity 301: NLT 5 mEq of acid is consumed by the minimum single dose recommended in the labeling, and NLT the number of mEq calculated:
Result = [(FM × M) × 0.8] + [(FC × C) × 0.9]
FM== theoretical acid-neutralizing capacity of MgCO3, 0.024 mEq
M== quantity of MgCO3 in the specimen tested, based on the labeled quantity (mg)
FC== theoretical acid-neutralizing capacity of CaCO3, 0.02 mEq
C== quantity of CaCO3 in the specimen tested, based on the labeled quantity (mg)
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in tight containers, and avoid freezing.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Elena Gonikberg, Ph.D.
Principal Scientific Liaison
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(SM32010) Monographs - Small Molecules 3
61 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
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(GCM2010) General Chapters - Microbiology
62 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
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(GCM2010) General Chapters - Microbiology
USP35–NF30 Page 2448