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 90.0 percent and not more than 110.0 percent of the labeled amount of betaxolol (C18H29NO3).
Packaging and storage— Preserve in tight containers.
USP Reference standards 11
USP Betaxolol Hydrochloride RS Click to View Structure
Identification— Prepare a test solution by diluting a suitable volume of it with water to obtain a solution containing about 2.5 mg of betaxolol per mL. Separately apply 5 µL of the test solution and 5 µL of a Standard solution of USP Betaxolol Hydrochloride RS in water containing about 2.75 mg per mL to a suitable thin-layer chromatographic plate (see Chromatography 621) 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 1 in 1000 solution of ninhydrin in isopropyl alcohol, and heat the plate at 105 for 10 minutes. Locate the spots on the plate: the RF value of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution.
Sterility 71 It meets the requirements when tested as directed for Membrane Filtration under Test for Sterility of the Product to be Examined.
pH 791: between 4.0 and 8.0.
pH 3.0 Buffer— Dissolve 7.1 g of anhydrous dibasic sodium phosphate in about 800 mL of water, adjust with phosphoric acid to a pH of 3.0, and dilute with water to make 1000 mL of solution.
Mobile phase— Prepare a suitable filtered and degassed mixture of pH 3.0 Buffer and acetonitrile (1:1). Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard preparation— Dissolve an accurately weighed quantity of USP Betaxolol Hydrochloride RS in pH 3.0 Buffer to obtain a solution having a known concentration of about 0.11 mg per mL.
Assay preparation— Transfer an accurately measured volume of Ophthalmic Solution, equivalent to about 10 mg of betaxolol, to a 100-mL volumetric flask. Dilute with pH 3.0 Buffer to volume, and mix.
Chromatographic system (see Chromatography 621)—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 1.1 mL per 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 1 and 3; the tailing factor is not less than 0.8 and not more than 2.0; the column efficiency is not less than 750 theoretical plates; and the relative standard deviation for replicate injections is not more than 2.0%.
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 C18H29NO3 in each mL of the Ophthalmic Solution taken by the formula:
(307.43 / 343.89)(100C / V)(rU / rS)
in which 307.43 and 343.89 are the molecular weights of betaxolol and betaxolol hydrochloride, respectively; C is the concentration, in mg per mL, of USP Betaxolol Hydrochloride RS in the Standard preparation; V is the volume, in mL, of Ophthalmic Solution taken; and rU and rS are the betaxolol peak responses obtained from the Assay preparation and the Standard preparation, respectively.
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