Identification—
Place about 50 mL of Oral Solution in a separator, add 25 mL of sodium bicarbonate solution (2 in 100), and extract with three 15-mL portions of isooctane. Wash the combined isooctane extracts with 15 mL of sodium bicarbonate solution (2 in 100), and discard the washing. Evaporate the isooctane solution on a steam bath to dryness, and dissolve the residue in 1 mL of carbon disulfide, filtering if necessary. Determine the IR absorption spectrum as directed under
Identification—Organic Nitrogenous Bases 
181
, obtaining the spectrum of
USP Cyproheptadine Hydrochloride RS as directed: the Oral Solution meets the requirements of the test.
Assay—
Standard preparation—
Dissolve an accurately weighed quantity of
USP Cyproheptadine Hydrochloride RS in
Mobile phase to obtain a solution having a known concentration of about 0.02 mg per mL.
Assay preparation—
Transfer an accurately measured volume of Oral Solution, equivalent to about 2 mg of cyproheptadine hydrochloride, to a 100-mL volumetric flask. Dilute with Mobile phase to volume, and mix. Pass the solution through a filter having a 0.45-µm or finer porosity.
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 cyproheptadine hydrochloride (C
21H
21N·HCl) in the portion of Oral Solution taken by the formula:
100C(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Cyproheptadine Hydrochloride RS in the
Standard preparation; and
rU and
rS are the cyproheptadine peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
Cyproheptadine Hydrochloride Syrup