Reserpine Elixir
(Current title—not to change until June 1,2005)
Monograph title change—to become official June 1,2005
See Reserpine Oral Solution
»Reserpine Elixir contains not less than 90.0percent and not more than 110.0percent of the labeled amount of C33H40N2O9.
Packaging and storage— Preserve in tight,light-resistant containers.
Identification— Evaporate about 2mLof the chloroform-methanol solution obtained from the Assay preparationas directed under Procedurein the Assay,in a test tube to dryness,add to the residue 0.5mLof glacial acetic acid,swirl for 1to 2minutes,and add 1mLof a 1in 50solution of vanillin in hydrochloric acid:a pink color is produced,and it becomes deep violet-red within a few minutes or as a result of warming the solution for 10to 20seconds.
Alcohol content á611ñ: between 11.0%and 13.0%of C2H5OH.
Assay—
Standard preparation— Dissolve 25.0mg of USP Reserpine RS,accurately weighed,in 0.25mLof chloroform,mix with about 30mLof methanol previously warmed to 50,transfer the mixture to a 250-mLvolumetric flask with the aid of warm methanol,cool the solution to room temperature,dilute with methanol to volume,and mix (Solution 1).Protect the solution from light.Just prior to use in the Assay,pipet 10mLof Solution 1into a 50-mLvolumetric flask,add 36mLof chloroform,and dilute with methanol to volume (Standard preparation).
Procedure— Transfer an accurately measured volume of Elixir,equivalent to about 1mg of reserpine,into a separator or a suitably stoppered,50-mLcentrifuge tube,add 5mLof citric acid solution (1in 50)and 10mLof chloroform,and shake for 2minutes.Separate and withdraw the chloroform.Wash the citric acid solution with two 10-mLportions of chloroform,adding the washings to the main chloroform solution.To the combined chloroform solutions add 10mLof sodium bicarbonate solution (1in 100),shake for 2minutes,and separate.Withdraw the chloroform,filtering it through a pledget of cotton,into a 50-mLvolumetric flask containing 14.0mLof methanol.Extract the aqueous bicarbonate layer in the extraction vessel with two 2-mLportions of chloroform,passing each portion successively through the filter into the volumetric flask.Add chloroform to volume,and mix (Assay preparation).
Pipet duplicate 5-mLaliquots of the chloroform-methanol solution and of the Standard preparation into separate,10-mLvolumetric flasks.Add 2.0mLof a 1in 10solution of hydrochloric acid in methanol to each flask.To one flask of each pair of duplicates (representing the Standard preparation and the extracted Assay preparation)add 1.0mLof a 3in 1000solution of sodium nitrite in dilute methanol (1in 2).To the second flask of each pair (constituting the blanks)add 1mLof dilute methanol (1in 2).Mix,and allow to stand for 30minutes.Add 0.5mLof ammonium sulfamate solution (1in 20)to each flask,add methanol to volume,mix,and allow to stand for 10minutes.Determine the absorbance of each solution in a 1-cm cell at the wavelength of maximum absorbance at about 390nm,with a suitable spectrophotometer,using a mixture of methanol,chloroform,and water (5.4:3.6:1)as the blank.Calculate the quantity,in mg,of C33H40N2O9in each mLof the Elixir taken by the formula:
(A-A0)U/V(A-A0)S,
in which Vis the volume,in mL,of Elixir taken,and the parenthetic expressions are the differences in absorbances of the nitrite-treated and blank solutions,respectively,from the Assay preparation(U)and the Standard preparation(S).
Auxiliary Information— Staff Liaison:Andrzej Wilk,Ph.D.,Senior Scientific Associate
Expert Committee:(PA5)Pharmaceutical Analysis 5
USP28–NF23Page 1713
Pharmacopeial Forum:Volume No.28(2)Page 362
Phone Number:1-301-816-8305