Benoxinate Hydrochloride Ophthalmic Solution
» Benoxinate Hydrochloride Ophthalmic Solution is a sterile solution of Benoxinate Hydrochloride in water. It contains not less than 95.0 percent and not more than 105.0 percent of the labeled amount of C17H28N2O3·HCl.
Packaging and storage Preserve in tight containers.
Identification Dilute a volume of Solution, equivalent to about 50 mg of benoxinate hydrochloride, with 0.01 N hydrochloric acid to 25 mL, and proceed as directed under IdentificationOrganic Nitrogenous Bases 181, beginning with Transfer the liquid to a separator: the solution meets the requirements of the test.
Sterility 71: meets the requirements.
pH 791: between 3.0 and 6.0.
Standard preparation Dissolve an accurately weighed quantity of USP Benoxinate Hydrochloride RS in 0.1 N hydrochloric acid to obtain a solution having a known concentration of about 400 µg per mL.
Assay preparation Transfer a volume of Ophthalmic Solution, equivalent to about 20 mg of benoxinate hydrochloride, to a separator containing 15 mL of water, add 1 mL of ammonium hydroxide, and extract with five 20-mL portions of ether. Wash the combined ether extracts with 10 mL of water, extract the water washing with 10 mL of ether, and add this ether extract to the main extract. Extract the ether solution with three 5-mL portions of 0.1 N hydrochloric acid, collect the acid extracts in a 50-mL volumetric flask, dilute with 0.1 N hydrochloric acid to volume, and mix.
Procedure Transfer 5.0 mL each of the Standard preparation, the Assay preparation, and 0.1 N hydrochloric acid to provide a blank, to separate 200-mL volumetric flasks. Dilute the contents of each flask with water to volume, and mix. Concomitantly determine the absorbances of the solutions in 1-cm cells at the wavelength of maximum absorbance at about 308 nm, with a suitable spectrophotometer, using the blank to set the instrument. Calculate the quantity, in mg, of C17H28N2O3·HCl in each mL of the Ophthalmic Solution taken by the formula:
(0.05C / V)(AU / AS)in which C is the concentration, in µg per mL, of USP Benoxinate Hydrochloride RS in the Standard preparation; V is the volume, in mL, of Ophthalmic Solution taken; and AU and AS are the absorbances of the solutions from the Assay preparation and the Standard preparation, respectively.
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USP32NF27 Page 1638