Alumina and Magnesia Tablets
» Alumina and Magnesia Tablets contain not less than 90.0 percent and not more than 110.0 percent of the labeled amounts of aluminum hydroxide [Al(OH)3] and magnesium hydroxide [Mg(OH)2].
Packaging and storage— Preserve in well-closed containers.
Labeling— Tablets prepared with the use of Dried Aluminum Hydroxide Gel may be labeled to state the aluminum hydroxide content in terms of the equivalent amount of dried aluminum hydroxide gel, on the basis that each mg of dried gel is equivalent to 0.765 mg of Al(OH)3.
A: To a 0.7-g portion of finely powdered Tablets add 10 mL of 3 N hydrochloric acid and 5 drops of methyl red TS, heat to boiling, and add 6 N ammonium hydroxide until the color of the solution changes to deep yellow. Continue boiling for 2 minutes, and filter: the filtrate responds to the tests for Magnesium 191.
B: Wash the precipitate obtained in Identification test A with a hot solution of ammonium chloride (1 in 50), and dissolve the precipitate in hydrochloric acid: the solution responds to the tests for Aluminum 191.
Disintegration 701: 10 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 alumina and to magnesia.
Acid-neutralizing capacity 301 The acid consumed by the minimum single dose recommended in the labeling is not less than 5 mEq, and not less than the number of mEq calculated by the formula:
0.55(0.0385A) + 0.8(0.0343 M)
in which 0.0385 and 0.0343 are the theoretical acid-neutralizing capacities, in mEq, of Al(OH)3 and Mg(OH)2, respectively, and A and M are the quantities, in mg, of Al(OH)3 and Mg(OH)2 in the specimen tested, based on the labeled quantities.
Assay for aluminum hydroxide—
Edetate disodium titrant— Prepare and standardize as directed in the Assay under Ammonium Alum.
Assay preparation— Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 1200 mg of aluminum hydroxide, to a 150-mL beaker, add 20 mL of water, stir, and slowly add 30 mL of 3 N hydrochloric acid. Proceed as directed for Assay preparation in the Assay for aluminum hydroxide under Alumina and Magnesia Oral Suspension, beginning with “Heat gently, if necessary.”
Procedure— Proceed as directed for Procedure in the Assay for aluminum hydroxide under Alumina and Magnesia Oral Suspension. Each mL of 0.05 M Edetate disodium titrant is equivalent to 3.900 mg of Al(OH)3.
Assay for magnesium hydroxide—
Assay preparation— Prepare as directed in the Assay for aluminum hydroxide.
Procedure— Proceed as directed for Procedure in the Assay for magnesium hydroxide under Alumina and Magnesia Oral Suspension.
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
(SM32010) Monographs - Small Molecules 3
701 Margareth R.C. Marques, Ph.D.
Senior Scientific Liaison
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USP35–NF30 Page 2116
Pharmacopeial Forum: Volume No. 27(3) Page 2515