Betaxolol Ophthalmic Solution
»Betaxolol Ophthalmic Solution is a sterile,aqueous,isotonic solution of Betaxolol Hydrochloride.It contains a suitable antimicrobial preservative.It contains the equivalent of not less than 90.0percent and not more than 110.0percent of the labeled amount of betaxolol (C18H29NO3).
Packaging and storage— Preserve in tight containers.
Identification— Prepare a test solution by diluting a suitable volume of it with water to obtain a solution containing about 2.5mg of betaxolol per mL.Separately apply 5µLof the test solution and 5µLof a Standard solution of USP Betaxolol Hydrochloride RSin water containing about 2.75mg per mLto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of silica gel.Allow the spots to dry,and develop the chromatogram in a chromatographic chamber,using a solvent system consisting of a mixture of chloroform,isopropyl alcohol,and ammonium hydroxide (70:30:2)until the solvent front has moved about three-fourths of the length of the plate.Remove the plate from the developing chamber,mark the solvent front,and allow the plate to air-dry.Spray the plate with a 1in 1000solution of ninhydrin in isopropyl alcohol,and heat the plate at 105for 10minutes.Locate the spots on the plate:the RFvalue of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution.
Sterility á71ñ— It meets the requirements when tested as directed for Membrane Filtration under Test for Sterility of the Product to be Examined.
pHá791ñ: between 4.0and 8.0.
Assay—
pH3.0Buffer— Dissolve 7.1g of anhydrous dibasic sodium phosphate in about 800mLof water,adjust with phosphoric acid to a pHof 3.0,and dilute with water to make 1000mLof solution.
Mobile phase— Prepare a suitable filtered and degassed mixture of pH3.0Bufferand acetonitrile (1:1).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).
Standard preparation— Dissolve an accurately weighed quantity of USP Betaxolol Hydrochloride RSin pH3.0Bufferto obtain a solution having a known concentration of about 0.11mg per mL.
Assay preparation— Transfer an accurately measured volume of Ophthalmic Solution,equivalent to about 10mg of betaxolol,to a 100-mLvolumetric flask.Dilute with pH3.0Bufferto volume,and mix.
Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 280-nm detector and a 4-mm ×25-cm column that contains packing L1.The flow rate is about 1.1mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the capacity factor,k¢,for the main betaxolol peak is between 1and 3;the tailing factor is not less than 0.8and not more than 2.0;the column efficiency is not less than 750theoretical plates;and the relative standard deviation for replicate injections is not more than 2.0%.
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 C18H29NO3in each mLof the Ophthalmic Solution taken by the formula:
(307.43/343.89)(100C/V)(rU/rS),
in which 307.43and 343.89are the molecular weights of betaxolol and betaxolol hydrochloride,respectively;Cis the concentration,in mg per mL,of USP Betaxolol Hydrochloride RSin the Standard preparation;Vis the volume,in mL,of Ophthalmic Solution taken;and rUand rSare the betaxolol peak responses obtained from the Assay preparationand the Standard preparation,respectively.
Auxiliary Information— Staff Liaison:Lawrence Evans,III,Ph.D.,Scientist
Expert Committee:(PA6)Pharmaceutical Analysis 6
USP28–NF23Page 253
Phone Number:1-301-816-8389