Identification—
A:
Place a portion of Oral Suspension, equivalent to about 50 mg of diazoxide, in a 50-mL volumetric flask, add 30 mL of 0.1 N sodium hydroxide, shake for 30 minutes, dilute with 0.1 N sodium hydroxide to volume, and mix: the solution so obtained responds to the
Thin-Layer Chromatographic Identification Test 
201
, a solvent system consisting of a mixture of ethyl acetate, methanol, and ammonium hydroxide (17:4:3) being used.
B:
The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, both relative to the internal standard, as obtained in the Assay.
Assay—
Mobile phase, Internal standard solution, Standard preparation, and Chromatographic system—
Prepare as directed in the
Assay under
Diazoxide.
Assay preparation—
Transfer an accurately measured volume of freshly mixed Oral Suspension, equivalent to about 100 mg of diazoxide, to a 50-mL centrifuge tube, add 2 mL of water and 35 mL of methanol, shake for 15 minutes, and centrifuge for 5 minutes. Transfer the supernatant to a 200-mL volumetric flask. Repeat the extraction process two times, beginning with the addition of 2 mL of water, combine the extracts in the 200-mL volumetric flask, dilute with methanol to volume, and mix. Transfer 10.0 mL of this solution to a 100-mL volumetric flask, add 2.0 mL of Internal standard solution, dilute with a mixture of water and methanol (4:1) to volume, and mix.
Procedure—
Proceed as directed for
Procedure in the
Assay under
Diazoxide. Calculate the quantity, in mg, of diazoxide (C
8H
7ClN
2O
2S) in each mL of the Oral Suspension taken by the formula:
2(C/V)(RU / RS),
in which
C is the concentration, in µg per mL, of
USP Diazoxide RS in the
Standard preparation; V is the volume, in mL, of Oral Suspension taken; and
RU and
RS are the peak response ratios obtained from the
Assay preparation and the
Standard preparation, respectively.
