(-)-2,3,5,6-Tetrahydro-6-phenylimidazo[2,1-b]thiazole monohydrochloride [16595-80-5].
»Levamisole Hydrochloride contains not less than 98.5percent and not more than 101.0percent of C11H12N2S·HCl,calculated on the dried basis.
Packaging and storage Preserve in well-closed containers,protected from light.
Completeness of solution á641ñ Atest solution of 500mg of Levamisole Hydrochloride dissolved in 10mLof water meets the requirements.
Color of solution The test solution prepared for the test for Completeness of solutionis colorless or not more intensely colored than a color matching fluid prepared by mixing 2.5mLof Matching Fluid F(see Color and Achromicity á631ñ)with 97.5mLof 0.12Nhydrochloric acid.
A: The IRabsorption spectrum of a potassium bromide dispersion of it,previously dried,exhibits maxima only at the same wavelengths as that of a similar preparation of USP Levamisole Hydrochloride RS.
B: The color,size,and RFvalue of the principal spot in the chromatogram of Test solution Bobtained in the test for Chromatographic purity,when examined under short-wavelength UVlight,correspond to the respective characteristics of the principal spot in the chromatogram of Reference solution Aobtained in the test for Chromatographic purity.
C: Asolution of it responds to the tests for Chloride á191ñ.
Melting range á741ñ: between 226and 231.
Light absorption Its absorbance (see Spectrophotometry and Light-scattering á851ñ)at 310nm,determined in a 0.2Nmethanolic hydrochloric acid solution containing 1mg per mLusing a 1-cm cell,is not more than 0.20.
Specific rotation á781Sñ: between -121.5and -128.0.
Test solution: 50mg per mL,in water.
pHá791ñ: between 3.0and 4.5,in a solution (1in 20).
Loss on drying á731ñ: Dry it at 105for 4hours:it loses not more than 0.5%of its weight.
Residue on ignition á281ñ: not more than 0.1%.
Heavy metals,Method Iá231ñ: 0.001%.
Chromatographic purity Prepare a solution of it in methanol containing 50mg per mL(Test solution A).Dilute 1.0mLof Test solution Ato 10mLwith methanol,and mix (Test solution B).Prepare a solution of USP Levamisole Hydrochloride RSin methanol having a concentration of 5mg per mL(Reference solution A).Dilute 1.0mLof Test solution Bto 20mLwith methanol,and mix (Reference solution B).Apply separate 10-µLportions of the four solutions on the starting line to a suitable thin-layer chromatographic plate (see Chromatography á621ñ),coated with a 0.25-mm layer of chromatographic silica gel mixture.Allow the spots to dry,and develop the chromatogram in a solvent system consisting of a mixture of toluene,acetone,and ammonium hydroxide (60:40:1)until the solvent front has moved about three-fourths of the length of the plate.Remove the plate from the developing chamber,and dry it at 105for 15minutes.Locate the spots on the plate by examination under short-wavelength UVlight:any spot obtained from Test solution A,other than the one corresponding to levamisole,does not exceed,in size or intensity,the principal spot obtained from Reference solution B,corresponding to not more than 0.5%of any individual impurity.Expose the plate to iodine vapor in a closed chamber for 15minutes,and locate the spots on the plate:any spot obtained from Test solution A,other than the one corresponding to levamisole,does not exceed,in size or intensity,the principal spot obtained from Reference solution B,corresponding to not more than 0.5%of any individual impurity,and the total of all impurities found does not exceed 1.0%.
Assay Dissolve about 200mg of Levamisole Hydrochloride,accurately weighed,in 30mLof alcohol.Add 5.0mLof 0.01Nhydrochloric acid,and titrate with 0.1Nsodium hydroxide VS,determining the two inflection points potentiometrically.Determine the volume,in mL,of 0.1Nsodium hydroxide consumed between the two inflection points.Each mLof 0.1Nsodium hydroxide consumed is equivalent to 24.08mg of C11H12N2S·HCl.
Auxiliary Information Staff Liaison:Behnam Davani,Ph.D.,MBA,Senior Scientist
Expert Committee:(PA7)Pharmaceutical Analysis 7