A: The RF value of the principal spot observed in the chromatogram of the Test preparation corresponds to that of the Standard preparation in the test for Chromatographic purity.

B: The UV absorption spectrum of the Assay preparation, prepared as directed in the Assay, exhibits maxima and minima at the same wavelengths as that of a similar solution of USP Clofazimine RS, concomitantly measured.

Medium: water; 500 mL.

Apparatus 2: 50 rpm.

Time: 15 minutes.

Procedure— Place 1 Capsule in each vessel, and allow the Capsule to sink to the bottom of the vessel before starting rotation of the blade. Observe the Capsules, and record the time taken for each capsule shell to rupture.

Tolerances— The requirements are met if all of the Capsules tested rupture in not more than 15 minutes. If 1 or 2 of the Capsules rupture in more than 15 but not more than 30 minutes, repeat the test on 12 additional Capsules. Not more than 2 of the total of 18 Capsules tested rupture in more than 15 but not more than 30 minutes.

Ammonia solution, Chromatographic plate, and Procedure— Proceed as directed in the test for Chromatographic purity under Clofazimine.

Standard preparations— Dissolve an accurately weighed quantity of USP Clofazimine RS in methylene chloride, and mix to obtain Standard preparation A having a known concentration of about 0.5 mg per mL. Dilute portions of Standard preparation A quantitatively with methylene chloride to obtain Standard preparations B and C having known concentrations of 0.1 and 0.04 mg per mL, respectively.

Test preparation— To a portion of Capsule contents, equivalent to about 500 mg of clofazimine, add 25 mL of methylene chloride and 25 mL of 0.1 N sodium hydroxide, and sonicate for 30 minutes. Withdraw the methylene chloride layer, and filter through anhydrous sodium sulfate.

0.1 N Methanolic hydrochloric acid— Pipet 10 mL of hydrochloric acid into a 1000-mL volumetric flask containing about 500 mL of methanol, mix, and dilute with methanol to volume.

Reference solution— Pipet 5 mL of methylene chloride into a 50-mL volumetric flask, dilute with 0.1 N Methanolic hydrochloric acid to volume, and mix.

Standard preparation— Dissolve an accurately weighed quantity of USP Clofazimine RS in methylene chloride, and dilute quantitatively, and stepwise if necessary, with methylene chloride to obtain a solution having a known concentration of about 0.075 mg per mL. Transfer 5.0 mL of this solution to a 50-mL volumetric flask, dilute with 0.1 N Methanolic hydrochloric acid to volume, and mix.

Assay preparation— Remove, as completely as possible, the contents of not less than 20 Capsules with the aid of methylene chloride. Dissolve in methylene chloride, filter the solution through a pledget of cotton, and dilute quantitatively, and stepwise if necessary, with methylene chloride to obtain a solution having a concentration of about 0.075 mg per mL. Transfer 5.0 mL of this solution to a 50-mL volumetric flask, dilute with 0.1 N Methanolic hydrochloric acid to volume, and mix.

Procedure— Concomitantly determine the UV absorbances of the Standard preparation and the Assay preparation at the wavelength of maximum absorbance at about 491 nm, using the Reference solution as the blank. Calculate the quantity, in mg, of C27H22Cl2N4 in the Capsules taken by the formula: in which L is the labeled quantity, in mg, of clofazimine in each Capsule; D is the concentration, in mg per mL, of clofazimine in the Assay preparation, based on the labeled quantity and extent of dilution; C is the concentration, in mg per mL, of USP Clofazimine RS in the Standard preparation; and AU and AS are the absorbances of the Assay preparation and the Standard preparation, respectively.