Calcium Carbonate Tablets
DEFINITION
Calcium Carbonate Tablets contain NLT 90.0% and NMT 110.0% of the labeled amount of calcium carbonate (CaCO3). For Tablets labeled for any indication other than, or in addition to, antacid use, the Tablets contain NLT 90.0% and NMT 115.0% of the labeled amount of calcium carbonate.
IDENTIFICATION
• A. Identification Tests—General, Calcium 
191
: The addition of 6 N acetic acid to the Tablets produces effervescence, and the resulting solution, after being boiled to expel carbon dioxide and neutralized with 6 N ammonium hydroxide, meets the requirements.
191: The addition of 6 N acetic acid to the Tablets produces effervescence, and the resulting solution, after being boiled to expel carbon dioxide and neutralized with 6 N ammonium hydroxide, meets the requirements.ASSAY
• Procedure
Sample solution: Finely powder NLT 20 Tablets. Transfer a portion of the powder, equivalent to 200 mg of calcium carbonate, to a suitable crucible. Ignite to constant weight. Cool the crucible, add 10 mL of water, and dissolve the residue by adding sufficient 3 N hydrochloric acid, dropwise, to achieve complete solution.
Blank: 150 mL of water and 15 mL of 1 N sodium hydroxide
Titrimetric system
(See Titrimetry 541.)
541.)Mode: Direct titration
Titrant: 0.05 M edetate disodium VS
Indicator: 300 mg of hydroxy naphthol blue
Endpoint detection: Visual, change to distinct blue
Analysis: Transfer the Sample solution completely to a suitable container, and dilute with water to 150 mL. Add 15 mL of 1 N sodium hydroxide and 300 mg of hydroxy naphthol blue. Titrate with the Titrant.
Calculate the percentage of calcium carbonate (CaCO3) in the sample taken:
Result = [(VS 
VB) × M × F × 100]/W
VB) × M × F × 100]/W| VS | = | = volume of the Titrant consumed by the Sample solution (mL) |
| VB | = | = volume of the Titrant consumed by the Blank (mL) |
| M | = | = Titrant molarity (mmol/mL) |
| F | = | = equivalency factor, 100.09 mg/mmol |
| W | = | = weight of calcium carbonate taken (mg) |
Acceptance criteria: 90.0%–110.0% of the labeled amount of CaCO3. For Tablets labeled for any indication other than, or in addition to, antacid use, 90.0%–115.0% of the labeled amount of CaCO3
PERFORMANCE TESTS
• Dissolution 711
711 [Note—For Tablets labeled for any indication other than, or in addition to, antacid use. ]
Medium: 0.1 N hydrochloric acid; 900 mL
Apparatus 2: 75 rpm
Time: 30 min
Lanthanium chloride solution: 50 mg/mL of lanthanum chloride in 0.1 N hydrochloric acid
Standard stock solution: 100 µg/mL of calcium in 0.1 N hydrochloric acid
Standard solutions: Into separate 100-mL volumetric flasks containing 10.0 mL of Lanthanium chloride solution pipet 3-, 4-, 5-, and 6-mL portions of Standard stock solution and dilute each with 0.1 N hydrochloric acid to volume to obtain solutions with calcium concentrations of 3, 4, 5, and 6 µg/mL, respectively.
Sample solution: Filter a portion of the solution under test. Pipet a volume of the filtrate, estimated to contain 1 mg of calcium, into a 250-mL volumetric flask. Add 25.0 mL of Lanthanium chloride solution, and dilute with 0.1 N hydrochloric acid to volume.
Instrumental conditions
Mode: Atomic absorption spectrophotometry
Analytical wavelength: 422.8 nm
Lamp: Calcium hollow-cathode
Flame: Air–acetylene
Blank: Lanthanium chloride solution and 0.1 N hydrochloric acid (1:9)
Analysis
Samples: Standard solutions and Sample solution
Concomitantly determine the absorbances of the Standard solutions and the Sample solution against the Blank. Construct a standard curve by plotting absorbances versus calcium concentrations of the Standard solutions, then from it obtain the concentration, CS, in µg/mL of calcium, of the Sample solution.
Calculate the percentage of the labeled amount of calcium carbonate (CaCO3) dissolved:
Result = (Mr/Ar) × (C × D × V/L) × 100
| Mr | = | = molecular weight of calcium carbonate, 100.09 |
| Ar | = | = atomic weight of calcium, 40.08 |
| C | = | = measured concentration of calcium in the Sample solution (mg/mL) |
| D | = | = dilution factor for the Sample solution |
| V | = | = volume of Medium, 900 mL |
| L | = | = label claim (mg/Tablet) |
Tolerances: NLT 75% (Q) of the labeled amount of calcium carbonate (CaCO3) is dissolved.
• Uniformity of Dosage Units 905: Meet the requirements
905: Meet the requirementsSPECIFIC TESTS
• Acid-Neutralizing Capacity 301: For Tablets labeled for antacid use
301: For Tablets labeled for antacid useAnalysis: Proceed as directed in the chapter.
Acceptance criteria: NLT 5 mEq of acid is consumed by the minimum single dose recommended in the labeling, and NLT the number of mEq calculated as follows:
Result = (C × ANC) × F
| C | = | = quantity of CaCO3 in the sample tested (mg), based on the labeled amount |
| ANC | = | = theoretical acid-neutralizing capacity of CaCO3, 0.02 mEq/mg |
| F | = | = acceptance factor for the lower limit of the required acid-neutralizing capacity, 0.9 |
ADDITIONAL REQUIREMENTS
• Packaging and Storage: Preserve in well-closed containers.
• Labeling: Label it to indicate whether it is for use as an antacid, or as a dietary supplement, or both.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Natalia Davydova Scientific Liaison 1-301-816-8328 | (DS2010) Monographs - Dietary Supplements |
| 711 | Margareth R.C. Marques, Ph.D. Senior Scientific Liaison 1-301-816-8106 | (GCDF2010) General Chapters - Dosage Forms |
USP35–NF30 Page 2445
Pharmacopeial Forum: Volume No. 28(5) Page 1392