Fluorescein Sodium Ophthalmic Strips
» Fluorescein Sodium Ophthalmic Strips contain not less than 100.0 percent and not more than 160.0 percent of the labeled amount of fluorescein sodium (C20H10Na2O5).
Packaging and storage— Package not more than 2 Strips in a single-unit container in such manner as to maintain sterility until the package is opened. Package individual packages in a second protective container.
Labeling— The label of the second protective container bears a statement that the contents may not be sterile if the individual package has been damaged or previously opened. The label states the amount of fluorescein sodium in each Strip.
USP Reference standards 11
USP Diacetylfluorescein RS Click to View Structure
    C24H16O7    416.39
Identification— Cut the colored tip from 1 Strip, place it in a small test tube containing 1 mL of water, and agitate for 1 minute: the resulting solution of fluorescein sodium responds to Identification tests A and C under Fluorescein Sodium.
Sterility 71: meets the requirements.
Content uniformity— The content of C20H10Na2O5 in each of not less than 10 Strips, determined as directed in the Assay, is not less than 85.0% and not more than 175.0% of the labeled amount.
Assay—
Standard preparation— Prepare as directed in the Assay under Fluorescein Sodium.
Assay preparation— Remove 1 Strip from its package, taking care not to allow any portion of the tip to adhere to the packaging material, transfer to a 100-mL volumetric flask, add 50 mL of water, shake the flask vigorously, and dilute with water to volume. Shake occasionally, and, after 1 hour, mix the contents of the flask. Transfer an aliquot (V) of this solution, equivalent to about 100 µg of fluorescein sodium, to a 100-mL volumetric flask, dilute with water to volume, and mix. Transfer 3 mL of the resulting solution to a 100-mL volumetric flask containing 20 mL of pH 9.0 alkaline borate buffer (see Buffer Solutions in the section Reagents, Indicators, and Solutions), dilute with water to volume, and mix.
Procedure— Proceed as directed for Procedure in the Assay under Fluorescein Sodium. Calculate the quantity, in mg, of fluorescein sodium (C20H10Na2O5) in the Strip taken by the formula:
(333)(C/V)(IU / IS)
in which C is the concentration, in µg per mL, of fluorescein sodium in the Standard preparation; V is the volume of the aliquot of solution taken for the Assay preparation; and IU and IS are the fluorescence intensities observed for the Assay preparation and the Standard preparation, respectively. Calculate the average content from the individual assays of not less than 10 Strips.
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