Neomycin Sulfate and Dexamethasone Sodium Phosphate Ophthalmic Solution
»Neomycin Sulfate and Dexamethasone Sodium Phosphate Ophthalmic Solution is a sterile,aqueous solution of Neomycin Sulfate and Dexamethasone Sodium Phosphate.It contains the equivalent of not less than 90.0percent and not more than 130.0percent of the labeled amount of neomycin,and the equivalent of not less than 90.0percent and not more than 115.0percent of the labeled amount of dexamethasone phosphate (C22H30FO8P).It may contain one or more suitable buffers,dispersants,and preservatives.
NOTEWhere Neomycin Sulfate and Dexamethasone Sodium Phosphate Ophthalmic Solution is prescribed,without reference to the amount of neomycin or dexamethasone phosphate contained therein,a product containing 3.5mg of neomycin and 1.0mg of dexamethasone phosphate per mLshall be dispensed.
Packaging and storage Preserve in tight,light-resistant containers,and avoid exposure to excessive heat.
USP Reference standards á11ñ USP Dexamethasone RS.USP Dexamethasone Phosphate RS.USP Neomycin Sulfate RS.
A: It meets the requirements for neomycin underThin-Layer Chromatographic Identification Test á201BNPñ.
B: TheAssay preparation,prepared as directed in theAssay for dexamethasone phosphate,meets the requirements for theIdentification test under Dexamethasone Sodium Phosphate Cream.
Sterility á71ñ: meets the requirements.
pHá791ñ: between 6.0and 8.0.
Assay for neomycin Proceed as directed underAntibioticsMicrobial Assays á81ñ,using an accurately measured volume of Ophthalmic Solution diluted quantitatively and stepwise withBuffer No.3to yield aTest Dilution having a concentration assumed to be equal to the median dose level of the Standard (1.0µg of neomycin per mL).
Assay for dexamethasone phosphate
0.002M Phosphate buffer Dissolve 0.57g of dibasic sodium phosphate in water to obtain 2000mLof solution.
0.10M Phosphate buffer Dissolve 13.80g of monobasic sodium phosphate in water to obtain 1000mLof solution.
Mobile phase Prepare a suitable filtered mixture of0.10Mphosphate buffer and acetonitrile (690:310).Make adjustments if necessary (seeSystem SuitabilityunderChromatography á621ñ).
Standard preparation Dissolve an accurately weighed quantity of USP Dexamethasone Phosphate RSin0.002M Phosphate buffer to obtain a solution having a known concentration of about 125µg per mL.Transfer 20.0mLof this solution to a 100-mLvolumetric flask,dilute with0.002M Phosphate buffer to volume,mix,and pass through a suitable filter of 1µm or finer porosity.This solution contains about 25µg per mL.
Assay preparation Transfer an accurately measured volume of Ophthalmic Solution,equivalent to about 2.5mg of dexamethasone phosphate,to a 100-mLvolumetric flask,slowly dilute with0.002M Phosphate buffer to volume,mix,and pass through a suitable filter of 1µm or finer porosity.
Chromatographic system(see Chromatography á621ñ) The liquid chromatograph is equipped with a 254-nm detector and a 4-mm ×30-cm column that contains packing L1.The flow rate is about 1.3mLper minute.Chromatograph theStandard preparation,and measure the peak responses as directed underProcedure:the column efficiency is not less than 2000theoretical plates,the capacity factor,k¢,for the dexamethasone phosphate peak is not less than 1.05,and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure [NOTEUse peak areas where peak responses are indicated.]Separately inject equal volumes (about 50µL)of theStandard preparation and theAssay preparation into the chromatograph,record the chromatograms,and measure the areas for the major peaks.Calculate the quantity,in mg,of dexamethasone phosphate (C22H30FO8P),in each mLof the Ophthalmic Solution taken by the formula:
0.1(C/V)(rU/rS),in whichCis the concentration,in µg per mL,of USP Dexamethasone Phosphate RSin theStandard preparation;Vis the volume,in mL,of Ophthalmic Solution taken;andrUandrSare the dexamethasone phosphate peak responses obtained from theAssay preparation and theStandard preparation,respectively.
Auxiliary Information Staff Liaison:William W.Wright,Ph.D.,Scientific Fellow
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28NF23Page 1345Pharmacopeial Forum:Volume No.28(4)Page 1155