A: Macerate a portion of powdered Tablets, equivalent to about 300 mg of bisacodyl, with 100 mL of acetone. Heat on a steam bath to boiling, filter, and evaporate to about 20 mL. Add 200 mL of water, and warm the mixture on the steam bath, passing a stream of nitrogen over the surface to evaporate the acetone. After 30 minutes, cool the mixture, and filter through a sintered-glass funnel. Discard the filtrate, and dissolve the crystals in 50 mL of acetone. Evaporate the solution to about 15 mL, add about 75 mL of water, heat on a steam bath for 15 minutes, and then cool. Scratch the sides of the beaker to induce crystallization, filter the crystals, and dry at 100 for about 15 minutes: the bisacodyl so obtained responds to Identification test A under Bisacodyl.

B: The retention time of the major peak for bisacodyl in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

(Official January 1, 2007)

Mobile phase , Standard preparation, and Chromatographic system—Proceed as directed in the Assay under Bisacodyl Suppositories.

Assay preparation— Transfer an accurately weighed portion of finely powdered Tablets, equivalent to 100 mg of bisacodyl, to a 200-mL volumetric flask, add 25 mL of water, and shake by mechanical means for 15 minutes followed by sonication for 15 minutes. Add 100 mL of acetonitrile, and shake by mechanical means for 15 minutes followed by sonication for 15 minutes. Dilute with acetonitrile to volume, mix, and filter.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C22H19NO4 in the Tablets taken by the formula: in which C is the concentration, in mg per mL, of USP Bisacodyl RS in the Standard preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.