Calcium Carbonate Lozenges
»Calcium Carbonate Lozenges contain not less than 90.0percent and not more than 110.0percent of the labeled amount of calcium carbonate (CaCO3).
Packaging and storage— Preserve in well-closed containers.
Identification— The addition of 6Nhydrochloric acid to a Lozenge produces effervescence,and the resulting solution,after being boiled to expel carbon dioxide and then neutralized with 6Nammonium hydroxide,meets the requirements of the tests for Calcium á191ñ.
Uniformity of dosage units á905ñ: meet the requirements.
Acid-neutralizing capacity á301ñ— The acid consumed by the minimum single dose recommended in the labeling is not less than 5mEq of acid and not less than the number of mEq calculated by the formula:
0.9(0.02C),
in which 0.02is the theoretical acid-neutralizing capacity,in mEq of CaCO3;and Cis the quantity,in mg,of CaCO3in the specimen tested,based on the labeled quantity.
Sodium content (if so labeled)— [NOTE—The Standard solutionsand the Test solutionmay be modified,if necessary,to obtain solutions of suitable concentrations adaptable to the linear or working range of the instrument.]
Standard solutions— Transfer 2.542g of sodium chloride,previously dried at 105for 2hours,to a 1000-mLvolumetric flask.Dissolve in and dilute with water to volume,and mix.Transfer 10.0mLof this solution to a 100-mLvolumetric flask,dilute with water to volume,and mix.Transfer 10.0mLof this solution to a second 100-mLvolumetric flask,dilute with water to volume,and mix.To three separate 100-mLvolumetric flasks,transfer 2.0-,4.0-,and 6.0-mLportions of this stock standard solution,dilute with water to volume,and mix.These solutions contain 1.0g,3.0g,and 5.0g of sodium per mL,respectively.
Test solution— Use the stock solution used to prepare the Assay preparationin the Assay.Pass,if necessary,through a filter having a 0.5-µm or finer porosity to obtain a clear solution.Transfer 10.0mLof the clear solution to a 25-mLvolumetric flask,dilute with water to volume,and mix.
Procedure— Concomitantly determine the absorbances of the Standard solutionsand the Test solutionat the sodium emission line at 589.6nm with an atomic absorption spectrophotometer (see Spectrophotometry and Light-Scattering á851ñ)equipped with a sodium hollow-cathode lamp and an air–acetylene flame,using water as the blank.Plot the absorbances of the Standard solutionsversus their contents of sodium,in µg per mL,by drawing a straight line best fitting the three plotted points.From the graph so obtained determine the quantity,C,in µg,of sodium in each mLof the Test solution.Calculate the quantity of sodium,in mg,per Lozenge by the formula:
2.5C/N,
in which Nis the number of Lozenges taken to prepare the Assay preparation.It contains not more than 115.0%of the declared amount.
Assay— [NOTE—The Standard preparationsand the Assay preparationmay be modified,if necessary,to obtain solutions,of suitable concentrations,adaptable to the linear or working range of the instrument.]
Lanthanum chloride solution— Transfer 10g of potassium chloride and 20g of lanthanum chloride to a 2000-mLvolumetric flask.Add about 1000mLof water and 40mLof hydrochloric acid,mix,and allow to cool.Dilute with water to volume,and mix.
1N Hydrochloric acid— Transfer 83mLof hydrochloric acid to a 1000-mLvolumetric flask containing about 500mLof water,mix,and allow to cool.Dilute with water to volume,and mix.
Standard preparations— Transfer about 250mg of chelometric standard calcium carbonate,previously dried at 110for 2hours and then cooled in a desiccator and accurately weighed,to a 500-mLvolumetric flask.Add about 100mLof water and 12mLof 1N Hydrochloric acid,swirl to dissolve the calcium carbonate,and allow to cool.Dilute with water to volume,and mix.This stock solution contains about 500µg of calcium carbonate per mL.To three separate 100-mLvolumetric flasks add 2.0,3.0,and 4.0mLof this stock solution,dilute each with Lanthanum chloride solutionto volume,and mix.These Standard preparationscontain about 10,15,and 20µg of calcium carbonate per mL,respectively.
Assay preparation— Powder an accurately counted number of Lozenges,equivalent to about 3000mg of calcium carbonate.Transfer the powder to a 1000-mLvolumetric flask,add 100mLof 1N Hydrochloric acidand 300mLof water,and sonicate to dissolve the powder.Dilute with water to volume,and mix.Transfer 5.0mLof this solution to a 1000-mLvolumetric flask,dilute with Lanthanum chloride solutionto volume,and mix.
Procedure— Concomitantly determine the absorbances of the Standard preparationsand the Assay preparationat the calcium emission line at 422.7nm with an atomic absorption spectrophotometer (see Spectrophotometry and Light-Scattering á851ñ)equipped with a calcium hollow-cathode lamp and a nitrous oxide–acetylene flame,using Lanthanum chloride solutionas the blank.Plot the absorbances of the Standard preparationsversus their concentrations of calcium carbonate,in µg per mL,by drawing a straight line best fitting the three plotted points.From the graph so obtained,determine the concentration,C,in µg per mL,of calcium carbonate in the Assay preparation.Calculate the quantity,in mg,of calcium carbonate (CaCO3)per Lozenge by the formula:
200(C/N),
in which Nis the number of Lozenges taken to prepare the Assay preparation.
Auxiliary Information— Staff Liaison:Elena Gonikberg,Ph.D.,Scientist
Expert Committee:(PA4)Pharmaceutical Analysis 4
USP28–NF23Page 319
Pharmacopeial Forum:Volume No.28(6)Page 1778
Phone Number:1-301-816-8251