Magnesium Oxide Tablets
DEFINITION
Magnesium Oxide Tablets contain NLT 90.0% and NMT 110.0% of the labeled amount of magnesium oxide (MgO).
IDENTIFICATION
• A. Identification Tests—General, Magnesium 
191
191 Sample solution: Finely powder 1 Tablet. Transfer the powder to a beaker, add 10 mL of 3 N hydrochloric acid and 5 drops of methyl red TS, and heat to boiling. Add 6 N ammonium hydroxide until the color of the solution changes to deep yellow, then continue boiling for 2 min, and filter. Use the filtrate.
Acceptance criteria: Meet the requirements
ASSAY
• Procedure
Eriochrome black indicator solution: Dissolve 200 mg of eriochrome black T in a mixture of 15 mL of triethanolamine and 5 mL of dehydrated alcohol.
Sample solution: Finely powder NLT 20 Tablets. Transfer a portion of the powder, equivalent to 500 mg of magnesium oxide, to a beaker. Add 20 mL of water, and slowly add 40 mL of 3 N hydrochloric acid, with mixing. Heat the mixture to boiling, cool, and filter into a 200-mL volumetric flask. Wash the beaker with water, adding the washings to the filter. Add water to volume.
Analysis: Transfer 20.0 mL of the Sample solution to a 400-mL beaker. Add 180 mL of water and 20 mL of triethanolamine, and stir. Add 10 mL of ammonia–ammonium chloride buffer TS and 3 drops of Eriochrome black indicator solution. Cool the solution to 3
–4 by immersion of the beaker in an ice bath. Remove, and titrate with 0.05 M edetate disodium VS to a blue endpoint. Perform a blank determination, substituting 20 mL of water for the Sample solution, and make any necessary correction (see Titrimetry 541). Each mL of 0.05 M edetate disodium consumed is equivalent to 2.015 mg of MgO.
–4 by immersion of the beaker in an ice bath. Remove, and titrate with 0.05 M edetate disodium VS to a blue endpoint. Perform a blank determination, substituting 20 mL of water for the Sample solution, and make any necessary correction (see Titrimetry 541). Each mL of 0.05 M edetate disodium consumed is equivalent to 2.015 mg of MgO.Acceptance criteria: 90.0%–110.0%
PERFORMANCE TESTS
• Dissolution 711
711 Medium: 0.1 N hydrochloric acid; 900 mL
Apparatus 2: 75 rpm
Time: 45 min
Analysis: Using atomic absorption spectrophotometry at a wavelength of 285.2 nm, determine the amount of MgO dissolved, using filtered portions of the solution under test, suitably diluted with Medium if necessary, in comparison with a standard solution having a known concentration of magnesium in the same Medium.
Tolerances: NLT 75% (Q) of the labeled amount of MgO is dissolved.
• Uniformity of Dosage Units 905: Meet the requirements
905: Meet the requirementsSPECIFIC TESTS
• Acid-Neutralizing Capacity 301 (where Tablets are labeled as intended for antacid use): NLT 5 mEq of acid is consumed by the minimum single dose recommended in the labeling, and NLT 85.0% of the expected mEq value calculated from the results of the Assay is obtained. Each mg of MgO has an expected acid-neutralizing capacity value of 0.0492 mEq.
301 (where Tablets are labeled as intended for antacid use): NLT 5 mEq of acid is consumed by the minimum single dose recommended in the labeling, and NLT 85.0% of the expected mEq value calculated from the results of the Assay is obtained. Each mg of MgO has an expected acid-neutralizing capacity value of 0.0492 mEq.ADDITIONAL REQUIREMENTS
• Packaging and Storage: Preserve in well-closed containers.
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 1-301-816-8251 | (SM32010) Monographs - Small Molecules 3 |
| 711 | Margareth R.C. Marques, Ph.D. Senior Scientific Liaison 1-301-816-8106 | (GCDF2010) General Chapters - Dosage Forms |
USP35–NF30 Page 3752