Medium: 0.1Nhydrochloric acid;900mL.

Apparatus 2: 50rpm.

Time: 30minutes.

Procedure— Determine the amount of C21H21N·HCl dissolved by employing UVabsorption at the wavelength of maximum absorbance at about 285nm on filtered portions of the solution under test,suitably diluted with Dissolution Medium,if necessary,in comparison with a Standard solution having a known concentration of USP Cyproheptadine Hydrochloride RSin the same Medium.

Tolerances— Not less than 80%(Q)of the labeled amount of C21H21N·HCl is dissolved in 30minutes.

Methanesulfonic acid solution— Prepare a solution of methanesulfonic acid in water (3:1000).

Mobile phase— Prepare a filtered and degassed mixture of acetonitrile,isopropyl alcohol,and Methanesulfonic acid solution(20:15:65);while mixing adjust with triethylamine to a pHof 4.0±0.05.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve an accurately weighed quantity of USP Cyproheptadine Hydrochloride RSin Mobile phaseto obtain a solution having a known concentration of about 0.08mg per mL.

Assay preparation— Transfer a number of Tablets,accurately weighed,equivalent to 80mg of cyproheptadine hydrochloride,to a 1-liter volumetric flask,dissolve by sonication in 500mLof Mobile phasefor 15minutes,and agitate for 30minutes.Dilute with Mobile phaseto volume,and mix.Pass through a filter having a 0.45-µm or finer porosity.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 285-nm detector and a 3.9-nm ×15-cm column that contains packing L1.The flow rate is about 1mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the tailing factor is not more than 2.5;and the relative standard deviation for replicate injections is not more than 2%.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of C21H21N·HCl in each of the Tablets taken by the formula: in which Cis the concentration,in mg per mL,of USP Cyproheptadine Hydrochloride RSin the Standard preparation;Nis the number of Tablets taken for the Assay preparation;and rUand rSare the cyproheptadine peak responses obtained from the Assay preparationand the Standard preparation,respectively.