(Ph. Eur. monograph 0042)
Action and use
Antacid; osmotic laxative.
Preparations
Aromatic Magnesium Carbonate Mixture
Kaolin Mixture
Magnesium Sulfate Mixture
Magnesium Trisilicate Mixture
DEFINITION
Hydrated basic magnesium carbonate.
Content
40.0 per cent to 45.0 per cent, calculated as MgO (Mr 40.30).
CHARACTERS
Appearance
White or almost white powder.
Solubility
Practically insoluble in water. It dissolves in dilute acids with effervescence.
IDENTIFICATION
A. Untapped bulk density (2.9.34): maximum 0.15 g/mL.
B. It gives the reaction of carbonates (2.3.1).
C. Dissolve about 15 mg in 2 mL of dilute nitric acid R and neutralise with dilute sodium hydroxide solution R. The solution gives the reaction of magnesium (2.3.1).
TESTS
Solution S
Dissolve 5.0 g in 100 mL of dilute acetic acid R. When the effervescence has ceased, boil for 2 min, allow to cool and dilute to 100 mL with dilute acetic acid R. Filter, if necessary, through a previously ignited and tared porcelain or silica filter crucible of suitable porosity to give a clear filtrate. Keep the residue for the test for
substances insoluble in acetic acid.
Appearance of solution
Solution S is not more intensely coloured than reference solution B4 (2.2.2, Method II).
Soluble substances
Maximum 1.0 per cent.
Mix 2.00 g with 100 mL of water R and boil for 5 min. Filter whilst hot through a sintered-glass filter (40) (2.1.2), allow to cool and dilute to 100 mL with water R. Evaporate 50 mL of the filtrate to dryness and dry at 100-105 °C. The residue weighs a maximum of 10 mg.
Substances insoluble in acetic acid
Maximum 0.05 per cent.
Any residue obtained during the preparation of solution S, washed, dried and ignited at 600 ± 50 °C, weighs a maximum of 2.5 mg.
Chlorides (2.4.4)
Maximum 700 ppm.
Dilute 1.5 mL of solution S to 15 mL with water R.
Sulfates (2.4.13)
Maximum 0.3 per cent.
Dilute 1 mL of solution S to 15 mL with distilled water R.
Elemental impurities
Any method that fulfils the requirements of general chapter 2.4.20. Determination of elemental impurities may be used.
| Element | Maximum content (ppm) |
| Arsenic | 1 |
| Cobalt | 1 |
| Nickel | 50 |
| Vanadium | 5 |
Calcium (2.4.3)
Maximum 0.75 per cent.
Dilute 2.6 mL of solution S to 150 mL with distilled water R. 15 mL of the solution complies with the test.
Iron (2.4.9)
Maximum 400 ppm.
Dissolve 0.1 g in 3 mL of dilute hydrochloric acid R and dilute to 10 mL with water
R. Dilute 2.5 mL of this solution to 10 mL with water R.
ASSAY
Dissolve 0.150 g in a mixture of 2 mL of dilute hydrochloric acid R and 20 mL of water R. Carry out the complexometric titration of magnesium (2.5.11).
1 mL of 0.1 M sodium edetate is equivalent to 4.030 mg of MgO.
FUNCTIONALITY-RELATED CHARACTERISTICS
This section provides information on characteristics that are recognised as being relevant control parameters for one or more functions of the substance when used as an excipient (see chapter 5.15). Some of the characteristics described in the Functionality-related characteristics section may also be present in the mandatory part of the monograph since they also represent mandatory quality criteria. In such cases, a cross-reference to the tests described in the mandatory part is included in the Functionality-related characteristics section. Control of the characteristics can contribute to the quality of a medicinal product by improving the consistency of the manufacturing process and the performance of the medicinal product
during use. Where control methods are cited, they are recognised as being suitable for the purpose, but other methods can also be used. Wherever results for a particular characteristic are reported, the control method must be indicated.
The following characteristics may be relevant for light magnesium carbonate used as filler in oral solid dosage forms.
