Dexamethasone Ophthalmic Suspension
»Dexamethasone Ophthalmic Suspension is a sterile,aqueous suspension of dexamethasone containing a suitable antimicrobial preservative.It may contain suitable buffers,stabilizers,and suspending and viscosity agents.It contains not less than 90.0percent and not more than 110.0percent of the labeled amount of C22H29FO5.
Packaging and storage— Preserve in tight containers.
Identification— Transfer a volume of Ophthalmic Suspension,equivalent to about 2.5mg of dexamethasone,to a test tube,add 5mLof chloroform,and shake.Centrifuge,and apply 10µLof the chloroform layer and 10µLof a Standard solution of USP Dexamethasone RSin chloroform containing 500µg per mLon a thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel mixture.Develop the chromatogram in Solvent Aas directed under Single-steroid Assay á511ñ.Mark the solvent front,and locate the spots on the plate by spraying with a 1in 5solution of p-toluenesulfonic acid in a mixture of 9volumes of alcohol and 1volume of propylene glycol,and heating until spots appear.The RFvalue of the principal spot obtained from the solution under test corresponds to that obtained from the Standard solution.
Sterility á71ñ: meets the requirements.
pHá791ñ: between 5.0and 6.0.
Assay—
Mobile phase— Prepare a filtered and degassed mixture of water and acetonitrile (60:40).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).
Standard preparation— Dissolve an accurately weighed quantity of USP Dexamethasone RSin Mobile phase,and dilute quantitatively,and stepwise if necessary,with Mobile phaseto obtain a solution having a known concentration of about 0.12mg per mL.
Assay preparation— Transfer an accurately measured volume of Ophthalmic Suspension,freshly mixed and free from air bubbles,equivalent to about 3mg of dexamethasone,to a 25-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.
Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm ×25-cm column that contains packing L1.The flow rate is about 2mLper minute.Chromatograph the Standard preparation,and record the peak response as directed for Procedure:the column efficiency determined from the analyte peak is not less than 1750theoretical plates;the tailing factor for the analyte peak is not more than 3.0;and the relative standard deviation for replicate injections is not more than 3.0%.
Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of C22H29FO5in each mLof the Ophthalmic Suspension taken by the formula:
25(C/V)(rU/rS),
in which Cis the concentration,in mg per mL,of USP Dexamethasone RSin the Standard preparation;Vis the volume,in mL,of Ophthalmic Suspension taken;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.
Auxiliary Information— Staff Liaison:Clydewyn M.Anthony,Ph.D.,Scientist
Expert Committee:(PA1)Pharmaceutical Analysis 1
USP28–NF23Page 590
Phone Number:1-301-816-8139