Chlordiazepoxide and Amitriptyline Hydrochloride Tablets
»Chlordiazepoxide and Amitriptyline Hydrochloride Tablets contain not less than 90.0percent and not more than 110.0percent of the labeled amount of chlordiazepoxide (C16H14ClN3O)and an amount of amitriptyline hydrochloride equivalent to not less than 90.0percent and not more than 110.0percent of the labeled amount of amitriptyline (C20H23N).
Packaging and storage— Preserve in tight,light-resistant containers.
Identification— The retention times of the major peaks in the chromatogram of the Assay preparationare the same as those of the Standard preparation,all relative to the internal standard,as obtained in the Assay.
Dissolution á711ñ—
Medium: simulated gastric fluid TS,prepared without pepsin;900mL.
Apparatus 1: 100rpm.
Time: 30minutes.
Procedure— Determine the absorbances of filtered portions of the solution under test,suitably diluted with Dissolution Medium,if necessary,and Standard solutions having known concentrations of USP Chlordiazepoxide RSand USP Amitriptyline Hydrochloride RSin the same Medium,at wavelengths of 239nm and 309nm,using Dissolution Mediumas the blank.Calculate the percentage of chlordiazepoxide (C16H14ClN3O)dissolved by the formula:
100(CD/L)(AU/AS),
in which Cis the concentration,in mg per mL,of USP Chlordiazepoxide RSin the Standard solutiondetermined at the wavelength of 309nm;Dis the dilution factor of the diluted solution under test;Lis the labeled amount,in mg,of chlordiazepoxide in each Tablet;and AUand ASare the absorbances of the solution under test and the chlordiazepoxide Standard solution,respectively,at the wavelength of 309nm.
Calculate the percentage of amitriptyline (C20H23N)dissolved by the formula:
100(277.40/313.86)(CD/L)(AX/AS),
in which 277.40and 313.86are the molecular weights of amitriptyline and amitriptyline hydrochloride,respectively;Cis the concentration,in mg per mL,of USP Amitriptyline Hydrochloride RSin the amitriptyline Standard solution;Dis the dilution factor of the diluted solution under test;Lis the labeled amount,in mg,of amitriptyline in each Tablet;ASis the absorbance of the amitriptyline Standard solutionat the wavelength of 239nm;and AXis defined by the formula:
AU239–AU309(C309AS239/C239AS309),
in which AU239and AU309are the absorbances of the solution under test measured at 239nm and 309nm,respectively;C309and C239are the concentrations,in mg per mL,of USP Chlordiazepoxide RSin the Standard solutionobtained at wavelengths of 309and 239nm,respectively;and AS239and AS309are the absorbances of the chlordiazepoxide Standard solutiondetermined at the wavelengths indicated in the subscripts.[NOTE—All of the chlordiazepoxide measurements may be made with either a single Standard solutionor two separate Standard solutions.]
Tolerances— Not less than 85%(Q)of the labeled amount of chlordiazepoxide (C16H14ClN3O)and an amount of amitriptyline hydrochloride equivalent to not less than 85%(Q)of the labeled amount of amitriptyline (C20H23N)are dissolved in 30minutes.
Uniformity of dosage units á905ñ: meet the requirements for Content Uniformitywith respect to chlordiazepoxide and to amitriptyline.
Related compounds— Transfer an accurately weighed portion of finely powdered Tablets,equivalent to about 25mg of chlordiazepoxide,to a 10-mLconical flask,add 2.5mLof acetone,and shake.Allow any undissolved particles to settle,and apply 50µLof the supernatant to a thin-layer chromatographic plate (see Chromatography á621ñ),coated with a 0.25-mm layer of chromatographic silica gel.Apply to the same plate 20µLof an acetone solution containing 1mg per mLof USP Chlordiazepoxide Related Compound A RSand 10µLof an acetone solution containing 50µg per mLof USP2-Amino-5-chlorobenzophenone RS.Develop the chromatogram in a chromatographic chamber (not previously saturated with the developing solvent)in ethyl acetate until the solvent front has moved about three-fourths of the length of the plate.Remove the plate from the developing chamber,mark the solvent front,and allow the solvent to evaporate.Locate the spots on the plate by lightly spraying with 2Nsulfuric acid,drying at 105for 15minutes,and then spraying in succession with sodium nitrite solution (1in 1000),ammonium sulfamate solution (1in 200),and N-(1-naphthyl)ethylenediamine dihydrochloride solution (1in 1000):any spots from the test solution are not greater in size or intensity than the spots at the respective RFvalues produced by the Standard solutions,corresponding to not more than 4.0%of chlordiazepoxide related compound A,and not more than 0.1%of 2-amino-5-chlorobenzophenone.
Assay— [NOTE—Use low-actinic glassware in this procedure.]
pH2.5Buffer— Mix 10.5mLof 0.20Nsodium hydroxide with 100mLof a solution consisting of 0.04Macetic acid,0.04Mphosphoric acid,and 0.04Mboric acid (prepared by dissolving 2.402g of glacial acetic acid,4.612g of phosphoric acid,and 2.473g of boric acid in sufficient water to obtain 1000mLof solution).
Solvent mixture— Prepare a mixture consisting of pH2.5Buffer,tetrahydrofuran,and methanol (5:4:1).
Mobile phase— Prepare a solution of 0.01Msodium lauryl sulfate in Solvent mixture.
Standard preparation— Dissolve accurately weighed quantities of USP Chlordiazepoxide RSand USP Amitriptyline Hydrochloride RSin Solvent mixture,and quantitatively dilute with Solvent mixtureto obtain a solution having known concentrations of about 1mg of USP Chlordiazepoxide RSper mLand about 2.8mg of USP Amitriptyline Hydrochloride RSper mL.Transfer 10.0mLof this solution to a 100-mLvolumetric flask,dilute with Solvent mixtureto volume,and mix.
Assay preparation— Weigh and finely powder not fewer than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 50mg of chlordiazepoxide and about 125mg of amitriptyline,to a 50-mLvolumetric flask,add Solvent mixtureto volume,sonicate to disperse the mixture,and allow undissolved particles to settle.Transfer 10.0mLof the resulting solution to a 100-mLvolumetric flask,dilute with Solvent mixtureto volume,and mix.Pass a portion of this solution through a filter having a 5-µm or finer porosity,and use the filtrate as the Assay preparation.
Chromatographic system (seeChromatography á621ñ)— The chromatograph is equipped with a 254-nm detector and a 3.9-mm ×30-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 resolution,R,is not less than 2.0;and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure— Separately inject equal volumes (about 20µL)of the Standard preparationand the Assay preparationinto the chromatograph,and record the chromatogram.Measure the peak responses at approximate retention times of 5minutes for chlordiazepoxide and 7minutes for amitriptyline hydrochloride.Calculate the quantity,in mg,of chlordiazepoxide (C16H14ClN3O)in the portion of Tablets taken by the formula:
0.5[C(rU/rS)]Z,
and calculate the quantity,in mg,of amitriptyline (C20H23N)in the portion of Tablets taken by the formula:
(277.40/313.86)[(0.5C)(rU/rS)]Y,
in which Zdenotes chlordiazepoxide;Ydenotes amitriptyline hydrochloride;277.40is the molecular weight of amitriptyline;313.86is the molecular weight of amitriptyline hydrochloride;Cis the concentration,in µg per mL,of USP Reference Standard in the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.
Auxiliary Information— Staff Liaison:Ravi Ravichandran,Ph.D.,Senior Scientist
Expert Committee:(PA3)Pharmaceutical Analysis 3
USP28–NF23Page 436
Pharmacopeial Forum:Volume No.27(6)Page 3263
Phone Number:1-301-816-8330