Packaging and storage—
Preserve in tight containers, and avoid freezing.
Labeling—
Oral Suspension 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.
Identification—
A:
To 5 g of Oral Suspension add 25 mL of 2 N sulfuric acid, stir, and allow to stand for 5 minutes. Add 25 mL of alcohol, stir, and place in an ice bath for 30 minutes. Filter while cold, retaining the filtrate for
Identification test
B. Wash the precipitate with 50 mL of 0.75 N sulfuric acid, and discard the washings: the precipitate so obtained, dissolved in 3 N hydrochloric acid and filtered, responds to the tests for
Calcium 
191
.
B:
To the filtrate obtained in
Identification test
A add 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, continue boiling for 2 minutes, and filter through hardened filter paper. (Retain the filtrate for
Identification test
C.) Wash the precipitate with 350 mL of a hot ammonium chloride solution (1 in 50), discarding the washings: the precipitate so obtained, dissolved in 3 N hydrochloric acid, responds to the tests for
Aluminum 191.
Microbial limits 61—
Its total aerobic microbial count does not exceed 100 cfu per mL, and it meets the requirements of the test for absence of
Escherichia coli.
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:
0.55(0.0385A) + 0.8(0.0343 M) + 0.9(0.02C),
in which 0.0385, 0.0343, and 0.02 are the theoretical acid-neutralizing capacities, in mEq, of Al(OH)
3, Mg(OH)
2, and CaCO
3, respectively, and
A,
M, and
C are the respective quantities, in mg, of Al(OH)
3, Mg(OH)
2, and CaCO
3 in the specimen tested, based on the labeled quantities.
Chloride 221—
Dissolve 5.0 g in 3 mL of nitric acid, add water to make 100 mL, and filter: a 10.0-mL portion of the filtrate shows no more chloride than corresponds to 1.0 mL of 0.020 N hydrochloric acid (0.14%).
Sulfate 221—
Dissolve 5.0 g in 7 mL of 3 N hydrochloric acid, with gentle heating. Cool, add water to make 250 mL, mix, and filter: a 20.0-mL portion of the filtrate shows no more sulfate than corresponds to 0.40 mL of 0.020 N sulfuric acid (0.1%).
Assay for aluminum hydroxide—
Edetate disodium titrant—
Prepare and standardize as directed in the
Assay under
Ammonium Alum.
Assay preparation—
Transfer an amount of Oral Suspension, previously shaken in its original container, equivalent to about 600 mg of aluminum hydroxide, to a tared beaker, and weigh accurately. Add 20 mL of water, stir, and slowly add 40 mL of 3 N hydrochloric acid. Heat gently, if necessary, to aid solution, cool, and transfer to a 200-mL volumetric flask. Wash the beaker with water, adding the washings to the flask, add water to volume, and mix.
Procedure—
Pipet 10 mL of the
Assay preparation into a 250-mL beaker, add 20 mL of water, then add, in the order named and with continuous stirring, 25.0 mL of 0.05 M
Edetate disodium titrant and 20 mL of acetic acid–ammonium acetate buffer TS, and heat the solution near the boiling temperature for 5 minutes. Cool, add 50 mL of alcohol and 2 mL of
dithizone TS, and mix. Titrate with 0.05 M zinc sulfate VS until the color changes from green-violet to rose-pink. Perform a blank determination, substituting 10 mL of water for the
Assay preparation, and make any necessary correction. Each mL of 0.05 M
Edetate disodium titrant consumed is equivalent to 3.900 mg of Al(OH)
3.
Assay for magnesium hydroxide—
Procedure—
Pipet a volume of
Assay preparation, equivalent to about 40 mg of magnesium hydroxide, into a 400-mL beaker, add 200 mL of water and 20 mL of trolamine, and mix. Add 50 mL of ammonia–ammonium chloride buffer TS and 2 drops of eriochrome black indicator solution (prepared by dissolving 200 mg of eriochrome black T in a mixture of 15 mL of trolamine and 5 mL of dehydrated alcohol, and mixing). Cool the solution to between 3
and 4
by immersing the beaker in an ice bath, and titrate with 0.05 M edetate disodium VS until the color changes to pure blue. Perform a blank determination, substituting 10 mL of water for the
Assay preparation, and make any necessary correction. From the volume of 0.05 M edetate disodium consumed, subtract the volume of 0.05 M edetate disodium consumed in the
Assay for calcium carbonate. Each mL of 0.05 M edetate disodium is equivalent to 2.916 mg of Mg(OH)
2.
Assay for calcium carbonate—
Procedure—
Pipet a volume of the Assay preparation, equivalent to about 50 mg of calcium carbonate, into a 400-mL beaker, and add 200 mL of water, 5 mL of sodium hydroxide solution (1 in 2), and 250 mg of hydroxy naphthol blue. Stir with a magnetic stirrer, and titrate immediately with 0.05 M edetate disodium VS until the solution is distinctly blue. Each mL of 0.05 M edetate disodium is equivalent to 5.004 mg of calcium carbonate (CaCO3).
Auxiliary Information—
Staff Liaison :
Elena Gonikberg, Ph.D., Scientist
Expert Committee : (MDGRE05) Monograph Development-Gastrointestinal Renal and Endocrine
USP29–NF24 Page 87
Pharmacopeial Forum : Volume No. 27(6) Page 3241
Phone Number : 1-301-816-8251
