Edition: BP 2025 (Ph. Eur. 11.6 update)
DEFINITION
Magnesium Sulfate Injection is a sterile solution of Magnesium Sulfate Heptahydrate in Water for Injections.
The injection complies with the requirements stated under Parenteral Preparations and with the following requirements.
Content of magnesium sulfate heptahydrate, MgSO4,7H2O
95.0 to 105.0% of the stated amount.
CHARACTERISTICS
A clear, colourless solution.
IDENTIFICATION
A. Yields reaction A characteristic of magnesium salts, Appendix VI.
B. Yields the reactions characteristic of sulfates, Appendix VI.
TESTS
Acidity or alkalinity
pH of the injection diluted, if necessary, to contain 5% w/v of Magnesium Sulfate Heptahydrate, 5.5 to 7.0, Appendix V L.
ASSAY
Dilute a volume containing 1.25 g of Magnesium Sulfate Heptahydrate to 100 mL with water. To 20 mL of this solution add 10 mL of ammonia buffer pH 10.9 and titrate with 0.05M disodium edetate VS using 0.1 g of mordant black 11 triturate as indicator, until the pink tint is discharged from the blue colour. Each mL of 0.05M disodium edetate VS is equivalent to
12.32 mg of MgSO4,7H2O.
LABELLING
The strength is stated as the percentage w/v of Magnesium Sulfate Heptahydrate and as the approximate concentration of magnesium ions (Mg2+) in millimoles per mL.
For a preparation containing 50% w/v of Magnesium Sulfate Heptahydrate (MgSO4,7H2O) the concentration of magnesium ions is approximately 2 millimoles per millilitre (2 mmol Mg2+/mL).
