BP 2025 (Ph. Eur. 11.6 update)
Action and use
Antacid.
DEFINITION
Co-magaldrox Oral Suspension is a suspension containing Magnesium Hydroxide and Dried Aluminium Hydroxide in asuitable flavoured vehicle. The amount of dried aluminium hydroxide is adjusted to give the required content of Al2O3.
The oral suspension complies with the requirements stated under Oral Liquids and with the following requirements.
Content of magnesium hydroxide, Mg(OH)2
90.0 to 110.0% of the stated amount.
Content of Al2O3
45.4 to 58.8% of the stated amount of dried aluminium hydroxide.
IDENTIFICATION
A. Mix 5 mL with 10 mL of 2M hydrochloric acid, add 5 drops of methyl red solution and heat to boiling. Add 6M ammonia until the solution becomes yellow, continue boiling for 2 minutes and filter. To 1 mL of the filtrate add 1 mL of 6M ammonia and 1 mL of 2M ammonium chloride; no precipitate is produced. Add 0.25M disodium hydrogen orthophosphate; a white, crystalline precipitate is produced which is insoluble in 6M ammonia.
B. To 5 mL add 10 mL of 2M hydrochloric acid. The solution yields the reaction characteristic of aluminium salts, Appendix VI.
TESTS
Microbial contamination
Carry out a quantitative evaluation for enterobacteria and certain other Gram-negative bacteria, Appendix XVI B1. 0.01 mL of the preparation gives a negative result, Table I (most probable number of bacteria per gram fewer than 10 ).
ASSAY
Co-magaldrox Oral Suspension
For Al2O3
To a weighed quantity containing 1.5 g of dried aluminium hydroxide add 20 mL of water, stir and slowly add 10 mL of hydrochloric acid. Heat gently, if necessary, to aid solution, cool, filter, wash the filter well with water, dilute the combined filtrate and washings to 200 mL with water and mix. Reserve a portion of the solution for the Assay for magnesium hydroxide. To 10 mL add 20 mL of water and, with continuous stirring, 25 mL of 0.05M disodium edetate VS followed by 20 mL of a mixture of equal volumes of 2M ammonium acetate and 2M acetic acid. Heat near the boiling point for 5
minutes, cool, add 50 mL of absolute ethanol and 3 mL of a freshly prepared 0.025% w/v solution of dithizone in absolute ethanol. Titrate the excess of disodium edetate with 0.05M zinc sulfate VS until the colour of the solution changes from greenish blue to reddish violet. Each mL of 0.05M disodium edetate VS is equivalent to 2.549 mg of Al2O3. Determine the weight per mL of the suspension, Appendix V G, and calculate the percentage content of Al2O3, weight in volume.
For magnesium hydroxide
To a volume of the solution reserved in the Assay for Al2O3 containing about 40 mg of magnesium hydroxide add 200 mL of water and 20 mL of triethanolamine and stir. Add 10 mL of ammonia buffer pH 10.9 and cool the solution to between 3° and 4° by immersion in iced water. Titrate the cooled solution with 0.05M disodium edetate VS using mordant black 11 solution as indicator. Each mL of 0.05M disodium edetate VS is equivalent to 2.916 mg of Mg(OH)2. Using the weight per mL of the suspension, calculate the percentage content of Mg(OH)2, weight in volume.
STORAGE
Co-magaldrox Oral Suspension should not be allowed to freeze.
