Identification—
Transfer a volume of Ophthalmic Suspension, equivalent to about 50 mg of natamycin, to a 200-mL volumetric flask, and add water to make a volume of 5 mL. Proceed as directed in the
Identification test under
Natamycin, beginning with “Add 100 mL of a 1 in 1000 solution of glacial acetic acid in methanol:” the specified result is obtained.
Assay—
[NOTE—Throughout the
Assay protect from direct light all solutions containing natamycin.
]
Mobile phase
,
Standard preparation, Resolution solution, and
Chromatographic system—Proceed as directed in the
Assay under
Natamycin.
Assay preparation—
Transfer an accurately measured volume of Ophthalmic Suspension, equivalent to about 50 mg of natamycin, to a 250-mL volumetric flask. Add 12.5 mL of tetrahydrofuran, and sonicate for 10 minutes. Add 150 mL of methanol, and swirl to dissolve. Add 60 mL of water, and mix. Allow to cool to room temperature. Dilute with water to volume, and mix. Filter this solution through a suitable membrane filter of 0.5-µm or finer porosity.
Procedure—
Proceed as directed in the
Assay under
Natamycin. Calculate the quantity, in mg, of C
33H
47NO
13 in each mL of the Ophthalmic Suspension taken by the formula:
0.25C(PS / V)(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Natamycin RS in the
Standard preparation, PS is the stated content, in µg per mg, of
USP Natamycin RS,
V is the volume, in mL, of Ophthalmic Suspension taken, and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
71
—
It meets the requirements as directed for Direct Inoculation of the Culture Medium under Test for Sterility of the Product to be Examined, using 0.25 mL of the Ophthalmic Suspension taken from each container.