Tetracaine Hydrochloride Cream
» Tetracaine Hydrochloride Cream contains Tetracaine Hydrochloride (C15H24N2O2·HCl) equivalent to not less than 90.0 percent and not more than 110.0 percent of the labeled amount of tetracaine (C15H24N2O2) in a suitable water-miscible base.
Packaging and storage Preserve in collapsible, lined metal tubes.
Identification, Ultraviolet Absorption 197U: Assay preparation compared to the Standard preparation from the Assay.
Microbial enumeration tests 61 and Tests for specified microorganisms 62 It meets the requirements of the tests for absence of Staphylococcus aureus and Pseudomonas aeruginosa.
Minimum fill 755: meets the requirements.
pH 791: between 3.2 and 3.8.
pH 6 Acetate buffer Dissolve 250 g of sodium acetate in about 500 mL of water in a 1000-mL volumetric flask, add 5.0 mL of glacial acetic acid, dilute with water to volume, and mix.
Standard preparation Transfer about 25 mg of USP Tetracaine Hydrochloride RS, accurately weighed, to a 100-mL volumetric flask, dissolve in isopropyl alcohol, add isopropyl alcohol to volume, and mix. Transfer 2.0 mL of this solution to another 100-mL volumetric flask, add 2.0 mL of pH 6 Acetate buffer, dilute with isopropyl alcohol to volume, and mix. The concentration of USP Tetracaine Hydrochloride RS in the Standard preparation is about 5 µg per mL.
Assay preparation Transfer an accurately weighed portion of Cream, equivalent to about 4.5 mg of tetracaine, to a 50-mL beaker, add 25 mL of isopropyl alcohol, and warm on a steam bath to dissolve the specimen completely. Transfer the solution with the aid of isopropyl alcohol to a 100-mL volumetric flask, dilute with isopropyl alcohol to volume, and mix. Transfer 10.0 mL of this solution to another 100-mL volumetric flask, add 2.0 mL of pH 6 Acetate buffer, dilute with isopropyl alcohol to volume, and mix.
Procedure Concomitantly determine the absorbances of the Assay preparation and the Standard preparation in 1-cm cells at the wavelength of maximum absorbance at about 310 nm, with a suitable spectrophotometer, using a 1 in 50 solution of pH 6 Acetate buffer in isopropyl alcohol as the blank. Calculate the quantity, in mg, of C15H24N2O2 in the portion of Cream taken by the formula:
(264.36/300.82)(C)(AU / AS)in which 264.36 and 300.82 are the molecular weights of tetracaine and tetracaine hydrochloride, respectively; C is the concentration, in µg per mL, of USP Tetracaine Hydrochloride RS in the Standard preparation; and AU and AS are the absorbances of the Assay preparation and the Standard preparation, respectively.
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USP32NF27 Page 3691