Azithromycin Capsules
»Azithromycin Capsules contain the equivalent of not less than 90.0percent and not more than 110.0percent of the labeled amount of azithromycin (C38H72N2O12).
Packaging and storage— Preserve in well-closed containers.Where packaged in unit-of-use containers,each container contains six 250-mg Capsules,and the label indicates the intended sequential day of use for each Capsule.
Identification— The retention time of the azithromycin peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,as obtained in the Assay.
Dissolution á711ñ— [NOTE—Use water that has a resistivity of not less than 18Mohm-cm.]
pH6.0sodium phosphate buffer— Prepare 6Lof 0.1Mdibasic sodium phosphate,adjust with about 40mLof hydrochloric acid to a pHof 6.0±0.05,add 600mg of trypsin,and mix.
Medium:pH6.0sodium phosphate buffer; 900mL.
Apparatus 2: 100rpm.
Time: 45minutes.
Standard solution— Transfer about 15mg of USP Azithromycin RS,accurately weighed,to a 50-mLvolumetric flask.Add 25mLof Medium,and sonicate briefly to dissolve.Dilute with Mediumto volume,and mix.Transfer 2.0mLof this solution to a 25-mLvolumetric flask,dilute with Mobile phase(prepared as directed in the Assay)to volume,and mix.Transfer 4.0mLof this solution to a second 25-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.
Test solution— Filter a portion of the solution under test through a filter having a porosity of 0.5µm or less.Transfer 2.0mLof the filtrate to a 25-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.Transfer 4.0mLof this solution to a second 25-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.
Procedure— Determine the amount of azithromycin (C38H72N2O12)dissolved,using filtered portions of the solution under test,and employing the procedure set forth in the Assay,making any necessary modifications.Calculate the quantity,in mg,of azithromycin (C38H72N2O12)dissolved by the formula:
70.31(CP)(rU/rS),
in which Cis the concentration,in mg per mL,of USP Azithromycin RSin the Standard solution;Pis the potency,in µg,of azithromycin (C38H72N2O12)per mg of USP Azithromycin RS;and rUand rSare the azithromycin peak responses obtained from the Test solutionand the Standard solution,respectively.
Tolerances— Not less than 75%(Q)of the labeled amount of azithromycin (C38H72N2O12)is dissolved in 45minutes.
Uniformity of dosage units á905ñ— meet the requirements.
Water,Method Iá921ñ: not more than 5.0%.
Assay—
Mobile phase,Standard preparation,Resolution solution,and Chromatographic system— Proceed as directed in the Assayunder Azithromycin.
Assay preparation— Remove,as completely as possible,the contents of not fewer than 20Capsules,and weigh accurately.Mix the combined contents,and transfer an accurately weighed quantity of the powder,equivalent to about 250mg of anhydrous azithromycin,to a 250-mLvolumetric flask.Add about 175mLof acetonitrile,and shake by mechanical means for 30minutes.Dilute with acetonitrile to volume,and mix.Place about 40mLof the resulting suspension in a centrifuge tube,and centrifuge.Transfer 2.0mLof the clear supernatant to a 50-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.Transfer 2.0mLof this solution to a 25-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.
Procedure— Proceed as directed for Procedurein the Assayunder Azithromycin.Calculate the quantity,in mg,of azithromycin (C38H72N2O12)in the portion of Capsules taken by the formula:
(312.5CP/4)(rU/rS),
in which Cis the concentration,in mg per mL,of USP Azithromycin RSin the Standard preparation;Pis the potency,in µg of azithromycin (C38H72N2O12)per mg,of USP Azithromycin RS;and rUand rSare the azithromycin peak responses obtained from the Assay preparationand the Standard preparation,respectively.
Auxiliary Information— Staff Liaison:William W.Wright,Ph.D.,Scientific Fellow
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 209
Pharmacopeial Forum:Volume No.27(6)Page 3394
Phone Number:1-301-816-8335