A: It meets the requirements for neomycin under Thin-Layer Chromatographic Identification Test 201BNP.

B: The retention time of the major peak for prednisolone acetate in the chromatogram of the Assay preparation corresponds to that of the Standard preparation, as obtained in the Assay for prednisolone acetate.

(Official January 1, 2007)

Mobile phase, Internal standard solution, Standard preparation, and Chromatographic system— Prepare as directed in the Assay for prednisolone acetate under Neomycin Sulfate and Prednisolone Acetate Ophthalmic Suspension.

Assay preparation— Transfer an accurately weighed portion of Ointment, equivalent to about 1 mg of prednisolone acetate, to a suitable container, add 2.0 mL of Internal standard solution, dilute with water-saturated chloroform to about 35 mL, and shake to dissolve the ointment. Transfer about 5 mL of this solution to a suitable container, and evaporate to dryness. Add about 5 mL of water-saturated chloroform, and sonicate for 5 minutes. Filter, and use the clear solution as the Assay preparation.

Procedure— Proceed as directed for Procedure in the Assay for prednisolone acetate under Neomycin Sulfate and Prednisolone Acetate Ophthalmic Suspension. Calculate the quantity, in mg, of prednisolone acetate (C23H30O6) in the portion of Ointment taken by the formula: in which C is the concentration, in µg per mL, of USP Prednisolone Acetate RS in the Standard preparation, and RU and RS are the peak response ratios of prednisolone acetate to betamethasone obtained from the Assay preparation and the Standard preparation, respectively.