Natamycin Ophthalmic Suspension

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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Natamycin Ophthalmic Suspension is a sterile suspension of Natamycin in a suitable aqueous vehicle. It contains not less than 90.0 percent and not more than 125.0 percent of the labeled amount of C₃₃H₄₇NO₁₃ . It contains one or more suitable preservatives.

Packaging and storage-Preserve in tight, light-resistant containers. The containers or individual cartons are sealed and tamper-proof so that sterility is assured at time of first use.

USP REFERENCE STANDARDS (11)

USP Natamycin RS

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.

STERILITY TESTS (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.

PH (791): between 5.0 and 7.5.

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 C₃₃H₄₇NO₁₃ in each mL of the Ophthalmic Suspension taken by the formula:

0.25C(P_s /V)(r_u /r_s )

S in which C is the concentration, in mg per mL, of USP Natamycin RS in the Standard preparation, P_s is the stated content, in µg per mg, of USP Natamycin RS, V is the volume, in ml., of Ophthalmic Suspension taken, and r_u and r_s are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.