Packaging and storage—
Preserve in well-closed containers.
Labeling—
Label the Tablets to indicate whether they are to be swallowed or to be chewed.
Identification—
Transfer a quantity of powdered Tablets, equivalent to about 2 g of magaldrate, to a 100-mL centrifuge tube. Add about 60 mL of water, cap, and shake for 3 minutes. Centrifuge the suspension, and discard the supernatant. Repeat the washing with three more 60-mL portions of water. Transfer the residue to a 250-mL beaker, and heat on a steam bath to dryness: the residue so obtained meets the requirements of the
Identification tests under
Magaldrate.
Microbial limits 
61
—
Tablets meet the requirements of the test for absence of
Escherichia coli.
Acid-neutralizing capacity—
Proceed as directed under
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:
0.8(0.0282M),
in which 0.0282 is the theoretical acid-neutralizing capacity, in mEq per mg, of magaldrate; and
M is the quantity, in mg, of the labeled amount of magaldrate.
Magnesium hydroxide content—
Test preparation—
Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 1 g of magaldrate, to a 100-mL volumetric flask, add 30 mL of dilute hydrochloric acid (1 in 10), shake for 15 minutes, dilute with water to volume, and mix.
Procedure—
Transfer 10.0 mL of
Test preparation to a 400-mL beaker, and proceed as directed in the test for
Magnesium hydroxide content under
Magaldrate, beginning with “and dilute with water to about 200 mL.” Not less than 492 mg and not more than 666 mg of magnesium hydroxide [Mg(OH)
2] per g of the labeled amount of magaldrate is found.
Aluminum hydroxide content—
Edetate disodium titrant—
Prepare and standardize as directed in the
Assay under
Ammonium Alum.
Procedure—
Transfer 10.0 mL of
Test preparation and 20 mL of water to a 250-mL beaker, and proceed as directed for
Procedure in the test for
Aluminum hydroxide content under
Magaldrate, beginning with “Add, with stirring, 25.0 mL of
Edetate disodium titrant.” Not less than 321 mg and not more than 459 mg of aluminum hydroxide [Al(OH)
3] per g of the labeled amount of magaldrate is found.
Assay—
Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 6 g of magaldrate, to a 200-mL volumetric flask. Add 100.0 mL of 2 N hydrochloric acid VS, and swirl by mechanical means for 30 minutes. Dilute with water to volume, mix, and filter. Transfer 100.0 mL of the filtrate to a beaker. Titrate the excess acid with 1 N sodium hydroxide VS to a pH of 3.0, determined potentiometrically. Perform a blank determination (see
Residual Titrations under
Titrimetry 541). Each mL of 2 N hydrochloric acid is equivalent to 70.80 mg of Al
5Mg
10(OH)
31(SO
4)
2.
