Edition: BP 2025 (Ph. Eur. 11.6 update)
Action and use
Treatment of iron-deficiency anaemia.
DEFINITION
Ferrous Fumarate Oral Suspension is a suspension of Ferrous Fumarate in a suitable flavoured vehicle.
The oral suspension complies with the requirements stated under Oral Liquids and with the following requirements.
Content of ferrous iron, Fe(II)
90.0 to 110.0% of the stated amount.
IDENTIFICATION
A. Mix a volume of the oral suspension containing about 0.6 g of Ferrous Fumarate with 20 mL of water, centrifuge and discard the supernatant liquid. Repeat with a further 20 mL of water. Add 15 mL of 3M hydrochloric acid to the residue, dissolve with minimum warming, cool and extract with two 50-mL quantities of ether. Wash the combined ether extracts with two 20-mL quantities of water, shake with anhydrous sodium sulfate, filter and evaporate to dryness. The infrared absorption spectrum of the residue, Appendix II A, is concordant with the reference spectrum of fumaric acid (RS 163).
B. Mix a volume of the oral suspension containing about 0.3 g of Ferrous Fumarate in 10 mL of water, centrifuge and discard the supernatant liquid. To 0.2 g of the residue add 10 mL of a mixture of equal volumes of hydrochloric acid and water, dissolve with minimum warming, cool and filter. The filtrate yields reaction A characteristic of iron salts, Appendix VI.
TESTS
Ferric iron
Disperse a quantity of the oral suspension containing 0.28 g of Ferrous Fumarate in 20 mL of water, centrifuge and decant the supernatant liquid into a 500-mL graduated flask. Dissolve the residue in 20 mL of 1M sulfuric acid with minimum warming, cool and transfer the resulting solution to the same graduated flask, dilute to 500 mL with water and filter. To 5 mL of the filtrate in a Nessler cylinder add 40 mL of water and 5 mL of a 10% w/v solution of ammonium thiocyanate and mix. Any red colour produced is not more intense than that obtained by treating in the same manner a mixture of 42 mL of water, 0.2 mL of 1M sulfuric acid and 3 mL of a 0.0173% w/v solution of ammonium iron(III) sulfate in 0.01M hydrochloric acid [6.0%, with respect to the content of Fe(II)].
ASSAY
Mix a quantity of the oral suspension containing 0.28 g of Ferrous Fumarate with 10 mL of water and 25 mL of nitric acid, carefully warm until the vigorous reaction subsides, add a further 25 mL of nitric acid, evaporate to about 10 mL and allow to cool. Carefully add 10 mL of sulfuric acid to the cooled solution, evaporate until white fumes are evolved, cool, add 10 mL of nitric acid and again evaporate until white fumes are evolved. Repeat the evaporation with 10 mL quantities of nitric acid until all of the organic matter has been destroyed. To the resulting solution add 10 mL of water and 0.5 g of ammonium oxalate, evaporate until white fumes are evolved, add 50 mL of water, boil until a clear solution is obtained, cool, dilute to 100 mL with water and add dilute potassium permanganate solution, drop wise, until a faint pink colour persists for 10 seconds. Add 10 mL of hydrochloric acid and 3 g of potassium iodide, allow to stand for 15 minutes protected from light, add 10 mL of chloroform and titrate the liberated iodine with 0.1M sodium thiosulfate VS, with vigorous shaking, until the chloroform layer becomes colourless. Repeat the procedure without the preparation being examined. The difference between the titrations represents the amount of sodium thiosulfate required. Each mL of 0.1M sodium thiosulfate VS is equivalent to 5.585 mg of Fe(II).
STORAGE
Ferrous Fumarate Oral Suspension should be protected from light.
LABELLING
The quantity of the active ingredient is stated both as the amount of ferrous fumarate and in terms of the equivalent amount of ferrous iron.
