A: Powder finely a number of Tablets. To a portion of the powder, equivalent to about 1 mg of levorphanol tartrate, add 1 mL of water, 1 drop of 3 N hydrochloric acid, and 2 drops of ferric chloride TS, and heat to boiling. To the hot solution add 1 mL of potassium ferricyanide solution (1 in 200): a bluish color develops.

B: Powder a number of Tablets, equivalent to about 60 mg of levorphanol tartrate, and transfer the mixture to a small separator. Add 10 mL of water, dissolve as much of the powder as possible, add about 400 mg of sodium bicarbonate, and extract with a 50-mL portion of chloroform. Evaporate the filtered chloroform extract on a steam bath to a small volume, dilute with chloroform to 10 mL, and determine the angular rotation: the solution is levorotatory (see Optical Rotation 781).

Medium: water; 500 mL.

Apparatus 2: 50 rpm.

Time: 30 minutes.

Procedure— Determine the amount of C17H23NO·C4H6O6·2H2O dissolved from UV absorbances at the wavelength of maximum absorbance at about 279 nm on filtered portions of the solution under test, suitably diluted with water, in comparison with a Standard solution having a known concentration of USP Levorphanol Tartrate RS in the same medium.

Tolerances— Not less than 75% (Q) of the labeled amount of C17H23NO·C4H6O6·2H2O is dissolved in 30 minutes.

Procedure for content uniformity— Transfer 1 Tablet to a glass-stoppered flask, add 25.0 mL of 0.1 N hydrochloric acid, and allow the Tablet to disintegrate. Shake well, and filter through a small filter paper, discarding the first portion of the filtrate. Dilute a portion of the filtrate quantitatively and stepwise, if necessary, to provide a solution containing about 80 µg of levorphanol tartrate per mL. Concomitantly determine the absorbances of this solution and of a solution of USP Levorphanol Tartrate RS in the same medium having a known concentration of about 80 µg of anhydrous levorphanol tartrate per mL, in 1-cm cells at the wavelength of maximum absorbance at about 279 nm, with a suitable spectrophotometer, using 0.1 N hydrochloric acid as the blank. Calculate the quantity, in mg, of C17H23NO·C4H6O6·2H2O in the Tablet taken by the formula: in which 443.49 and 407.47 are the molecular weights of the hydrated and anhydrous forms of levorphanol tartrate, respectively; T is the labeled quantity, in mg, of levorphanol tartrate in the Tablet; C is the concentration, in µg per mL, of USP Levorphanol Tartrate RS, on the anhydrous basis, in the Standard solution; D is the concentration, in µg per mL, of levorphanol tartrate in the solution from the Tablet, based on the labeled quantity per Tablet and the extent of dilution; and AU and AS are the absorbances of the solution from the Tablet and the Standard solution, respectively.

(Official January 1, 2007)