Alumina and Magnesia Oral Suspension
» Alumina and Magnesia Oral Suspension is a mixture containing aluminum hydroxide [Al(OH)3] and Magnesium Hydroxide [Mg(OH)2]. It contains the equivalent of 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]. It may contain a flavoring agent, and may contain suitable antimicrobial agents.
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.
A: To a solution of 5 g in 10 mL of 3 N hydrochloric acid add 5 drops of methyl red TS, heat to boiling, add 6 N ammonium hydroxide until the color of the solution changes to deep yellow, then 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 hot ammonium chloride solution (1 in 50), and dissolve the precipitate in hydrochloric acid: the solution responds to the tests for Aluminum 191.
Microbial enumeration tests 61 and Tests for specified microorganisms 62 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 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.
pH 791: between 7.3 and 8.5.
Chloride 221 Dissolve 5.0 g in the minimum volume of nitric acid required to achieve complete solution, add 1 mL of acid in excess, then add water to make 100 mL, and filter: a 10-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 5 mL of 3 N hydrochloric acid, with gentle heating. Cool, add water to make 250 mL, mix, and filter: a 20-mL portion of the filtrate shows no more sulfate than corresponds to 0.40 mL of 0.020 N sulfuric acid (0.1%).
Other requirements It meets the requirements of the tests for Arsenic and Heavy metals under Aluminum Hydroxide Gel.
Assay for aluminum hydroxide
Assay preparation Transfer an accurately measured quantity of Oral Suspension, previously well shaken in its original container, equivalent to about 1200 mg of aluminum hydroxide, to a suitable beaker. Add 20 mL of water, stir, and slowly add 10 mL of hydrochloric acid. Heat gently, if necessary, to aid solution, cool, and filter into a 200-mL volumetric flask. Wash the filter with water into the flask, add water to volume, and mix.
Procedure Pipet 10 mL of 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 Edetate disodium titrant and 20 mL of acetic acidammonium acetate buffer TS, and heat near the boiling point 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
Assay preparation Prepare as directed in the Assay for aluminum 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 triethanolamine, and stir. Add 10 mL of ammonia-ammonium chloride buffer TS and 3 drops of an eriochrome black indicator solution prepared by dissolving 200 mg of eriochrome black T in a mixture of 15 mL of triethanolamine and 5 mL of dehydrated alcohol, and mix. Cool the solution to between 3 and 4 by immersion of the beaker in an ice bath, then remove, and titrate with 0.05 M edetate disodium VS to a blue endpoint. 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 consumed is equivalent to 2.916 mg of Mg(OH)2.
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USP35NF30 Page 2115Pharmacopeial Forum: Volume No. 27(3) Page 2515