Ferumoxsil Oral Suspension
» Ferumoxsil Oral Suspension is an aqueous suspension of silicone-coated superparamagnetic iron oxide. It contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of iron (Fe). It contains a preservative and a thickening agent. It may contain suitable colors, flavors, and sweetening agents. Ferumoxsil is poly[N-(2-aminoethyl)-3-aminopropyl]siloxane-coated nonstoichiometric magnetite [FeOX(C5H13N2SiO2)Y].
Packaging and storage— Preserve in tight containers, and store at controlled room temperature.
Labeling— Label it to indicate that it is to be well-shaken for 1 minute before use, and that it is not to be used if there are indications that the package has been exposed to freezing temperatures.
Viscosity 911: between 11 and 60 centipoises.
Osmolarity 785: between 230 and 270 mOsmol per kg.
Microbial enumeration tests 61 and Tests for specified microorganisms 62 It meets the requirements of the tests for absence of Escherichia coli. The total aerobic microbial count does not exceed 100 cfu per mL.
pH 791: between 5.5 and 9.0.
Magnetic susceptibility—
Apparatus, Standard solutions, Balance constant, and Tube constant— Proceed as directed for Magnetic susceptibility under Ferumoxides Injection.
Procedure— Proceed as directed for Magnetic susceptibility under Ferumoxides Injection except to use undiluted Oral Suspension whenever Injection is indicated. Calculate the magnetic susceptibility, in cgs units, per g of iron in the Oral Suspension by the formula:
1000CTR/I
in which CT is the Tube constant; R is the balance reading, in cgs units; and I is the concentration, in mg per g, of iron in the Oral Suspension, as determined in the Assay for iron. The magnetic susceptibility is not less than 22,500 × 10–6 in cgs units per g of iron.
Settling— Prepare a mixture of Oral Suspension and water (1:5). Mix by gentle inversion, and determine the absorbance at 500 nm in a suitable spectrophotometer, using water as the blank. Cover the cell, and allow to stand undisturbed for 4 hours at room temperature. Without mixing, determine the absorbance again. Calculate the percentage of iron remaining in solution after settling by the formula:
100(A4 / A0)
in which A4 is the absorbance of the solution after standing for 4 hours; and A0 is the initial absorbance of the solution: not less than 80% is found.
Uniformity of dosage units 905
for oral suspension packaged in single-unit containers: meets the requirements.
Deliverable volume 698
for oral suspension packaged in multiple-unit containers: meets the requirements.
Assay for iron—
Iron standard solution and Standard preparations— Proceed as directed in the Assay for iron under Ferumoxides Injection.
Assay preparation— Transfer about 5 g of well-mixed Oral Suspension, accurately weighed, to a 100-mL volumetric flask. Add 2 mL of nitric acid, and mix. Transfer the flask to a boiling water bath, and boil for 30 minutes to obtain a yellowish solution. Allow to cool to room temperature, dilute with water to volume, and mix.
Procedure— Proceed as directed in the Assay for iron under Ferumoxides Injection. Calculate the iron concentrations, in µg per mL, of the three Standard preparations by the formula:
20(AS / A20)
in which AS is the absorbance of the relevant Standard preparation; and A20 is the absorbance of the Standard preparation containing 20 µg per mL. The reading for each Standard preparation, AS, is within 0.5 µg per mL of its nominal concentration. Measure the absorbance of the Assay preparation, and calculate the content of iron, in µg per mL, in the Oral Suspension by the formula:
2000(AU / A20)(1.01/W)
in which AU is the absorbance of the Assay preparation; A20 is the absorbance as defined above; 1.01 is the specific gravity of the Oral Suspension; and W is the weight, in g, of Oral Suspension taken to prepare the Assay preparation.
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USP35–NF30 Page 3185
Pharmacopeial Forum: Volume No. 29(6) Page 1885