Metoprolol Tartrate
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(C15H25NO3)2·C4H6O6 684.81

2-Propanol,1-[4-(2-methoxyethyl)phenoxy]-3-[(1-methylethyl)amino]-,(±)-,[R-(R*,R*)]-2,3-dihydroxybutanedioate (2:1)(salt).
(±)-1-(Isopropylamino)-3-[p-(2-methoxyethyl)phenoxy]-2-propanol L-(+)-tartrate (2:1)(salt).
1-(Isopropylamino)-3-[p-(2-methoxyethyl)phenoxy]-2-propanol (2:1)dextro-tartrate salt [56392-17-7].
»Metoprolol Tartrate contains not less than 99.0percent and not more than 101.0percent of (C15H25NO3)2·C4H6O6,calculated on the dried basis.
Packaging and storage— Preserve in tight,light-resistant containers.Store at 25,excursions permitted between 15and 30.
Identification,Infrared Absorption á197Mñ.
Specific rotation á781Sñ: between +6.5and +10.5(t=20).
Test solution: 20mg per mL,in water.
pHá791ñ: between 6.0and 7.0,in a solution (1in 10).
Loss on drying á731ñ— Dry it in vacuum at 60for 4hours:it loses not more than 0.5%of its weight.
Residue on ignition á281ñ: not more than 0.1%.
Chromatographic purity—
Standard solutionand Standard dilutions— Dissolve a suitable quantity of USP Metoprolol Tartrate RS,accurately weighed,in chloroform,and dilute quantitatively and stepwise with chloroform to obtain solutions having known concentrations of 1.0,0.5,0.2,and 0.1mg per mL,respectively.
Test solution— Dissolve a quantity of Metoprolol Tartrate in chloroform to obtain a solution containing 100mg per mL.
Chromatographic chamber— Line a suitable chamber (see Chromatography á621ñ)with absorbent paper,and pour into the chamber 250mLof a mixture of chloroform,methanol,and ammonium hydroxide (80:15:2).Saturate the chamber for 1.5hours before using.
Detecting reagent— Prepare separate solutions of potassium iodide (1in 100)and soluble starch (prepared by triturating 3g in 10mLof cold water and adding the mixture to 90mLof boiling water with constant stirring).Just prior to use,mix 10mLof each solution with 3mLof alcohol.
Procedure— Apply separately 5-µLportions of the Test solutionand each of the Standard dilutionsto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel mixture.Place the plate in the Chromatographic chamber,seal the chamber,and allow the chromatogram to develop until the solvent front has moved about three-fourths of the length of the plate.Remove the plate,and dry in a current of warm air until the odor of ammonia is no longer perceptible (about 45minutes).Place a beaker containing 0.5g of potassium permanganate in a chamber.Add 5mLof 6Nhydrochloric acid to the beaker,and allow to equilibrate for 5minutes.Place the plate in the chamber for 5minutes.Remove the plate from the chamber,allow to stand in a current of cool air for 1hour,and spray with Detecting reagent.If spots other than the principal spot are observed in the lane of the Test solution,estimate the concentration of each by comparison with the Standard dilutions:the spots from the 1.0,0.5,0.2,and 0.1mg per mLStandard dilutionscorrespond to 1.0%,0.5%,0.2%,and 0.1%of impurities,respectively;and the sum of any observed impurities in the Test solutionis not greater than 1.0%.
Organic volatile impurities,Method Iá467ñ: meets the requirements.
Assay— Dissolve about 280mg of Metoprolol Tartrate,accurately weighed,in 20mLof glacial acetic acid,and titrate with 0.1Nperchloric acid VS,determining the endpoint potentiometrically,using a glass electrode and a calomel electrode containing glacial acetic acid saturated with lithium chloride (see Titrimetry á541ñ).Perform a blank determination,and make any necessary correction.Each mLof 0.1Nperchloric acid is equivalent to 34.24mg of (C15H25NO3)2·C4H6O6.
Auxiliary Information— Staff Liaison:Andrzej Wilk,Ph.D.,Senior Scientific Associate
Expert Committee:(PA5)Pharmaceutical Analysis 5
USP28–NF23Page 1281
Pharmacopeial Forum:Volume No.29(5)Page 1536
Phone Number:1-301-816-8305