» Betaxolol Tablets contain an amount of Betaxolol Hydrochloride equivalent to not less than 90.0 percent and not more than 110.0 percent of the labeled amount of betaxolol hydrochloride (C18H29NO3·HCl).
Labeling— Label the Tablets to state both the content of the betaxolol active moiety and the content of betaxolol hydrochloride used in formulating them.
Procedure— Determine the amount of C18H29NO3·HCl dissolved by employing UV absorption at the wavelength of maximum absorbance at about 274 nm on filtered portions of the solution under test in comparison with a Standard solution having a known concentration of USP Betaxolol Hydrochloride RS in the same Medium. A 5-cm pathlength cell may be used for lower dosage levels.
Tolerances— Not less than 80% (Q) of the labeled amount of C18H29NO3·HCl is dissolved in 30 minutes.
in which C, is the concentration, in mg per mL, of USP Betaxolol Hydrochloride RS in the Standard solution; V is the volume, in mL, of 0.1 N hydrochloric acid used to dissolve the Tablet; and AU and AS are the absorbances of the solution from the Tablet and the Standard solution, respectively.
Mobile phase— Prepare a filtered mixture of 0.025 M pH 6.0 ammonium phosphate buffer, acetonitrile, and methanol (35:35:30). Mix, and degas under vacuum while stirring. Make adjustments if necessary (see System Suitability under Chromatography 621 ).
Standard preparation— Dissolve an accurately weighed quantity of USP Betaxolol Hydrochloride RS in Diluent to obtain a solution having a known concentration of about 2 mg per mL.
Assay preparation— Dissolve not fewer than 20 Tablets in an appropriate accurately measured volume of Diluent so that the final concentration, based on the labeled amount per Tablet, is about 2 mg of betaxolol hydrochloride per mL. Sonicate until the Tablets are disintegrated. Cool to room temperature, dilute with Diluent to volume, mix, and filter. Use the clear filtrate as the Assay preparation.
Chromatographic system (see Chromatography 621 )— The liquid chromatograph is equipped with a 273-nm detector and a 4.6-mm × 15-cm column that contains packing L1. The flow rate is about 1.5 mL per minute. Chromatograph the Standard preparation, record the chromatogram, and measure the peak response as directed for Procedure: the tailing factor is not more than 3.0, and the relative standard deviation for replicate injections is not more than 2.0%.
in which C is the concentration, in mg per mL, of USP Betaxolol Hydrochloride RS in the Standard preparation; V is the volume of Diluent used to dissolve the Tablets; N is the number of Tablets taken; and rU and rS are the betaxolol peak responses obtained from the Assay preparation and the Standard preparation, respectively.