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 90.0 percent and not more than 110.0 percent of the labeled amount of C22H29FO5.
Packaging and storage Preserve in tight containers.
USP Reference standards 11
Identification Transfer a volume of Ophthalmic Suspension, equivalent to about 2.5 mg of dexamethasone, to a test tube, add 5 mL of chloroform, and shake. Centrifuge, and apply 10 µL of the chloroform layer and 10 µL of a Standard solution of USP Dexamethasone RS in chloroform containing 500 µg per mL on a thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Develop the chromatogram in Solvent A as directed under Single-steroid Assay 511. Mark the solvent front, and locate the spots on the plate by spraying with a 1 in 5 solution of p-toluenesulfonic acid in a mixture of 9 volumes of alcohol and 1 volume of propylene glycol, and heating until spots appear. The RF value of the principal spot obtained from the solution under test corresponds to that obtained from the Standard solution.
Sterility 71: meets the requirements.
pH 791: between 5.0 and 6.0.
Mobile phase Prepare a filtered and degassed mixture of water and acetonitrile (60:40). Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard preparation Dissolve an accurately weighed quantity of USP Dexamethasone RS in Mobile phase, and dilute quantitatively, and stepwise if necessary, with Mobile phase to obtain a solution having a known concentration of about 0.12 mg per mL.
Assay preparation Transfer an accurately measured volume of Ophthalmic Suspension, freshly mixed and free from air bubbles, equivalent to about 3 mg of dexamethasone, to a 25-mL volumetric flask, dilute with Mobile phase to volume, and mix.
Chromatographic system (see Chromatography 621)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 2 mL per 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 1750 theoretical 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 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C22H29FO5 in each mL of the Ophthalmic Suspension taken by the formula:
25(C/V)(rU/rS)in which C is the concentration, in mg per mL, of USP Dexamethasone RS in the Standard preparation; 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.
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USP35NF30 Page 2839