Flucytosine Capsules
»Flucytosine Capsules contain not less than 90.0percent and not more than 110.0percent of the labeled amount of flucytosine (C4H4FN3O).
Packaging and storage— Preserve in tight,light-resistant containers.
Identification—
A: The UVabsorption spectrum of the solution from the Capsule contents obtained in the Assayexhibits maximum absorption at the same wavelength as that of the Standard solution,and the two spectra are similar between 260nm and 350nm.
B: Shake a portion of the contents of Capsules,equivalent to about 500mg of flucytosine,with 10mLof water.Filter,and to 2mLof the filtrate add 1mLof sodium pentacyanoaminoferrate reagent [prepared by dissolving 100mg of sodium (tri)pentacyanoaminoferrate in 20mLof sodium carbonate solution (1in 100)]and 1mLof 3percent hydrogen peroxide:on standing,a darker green is produced than that produced by a blank.
Dissolution á711ñ—
Medium: water;900mL.
Apparatus 2: 75rpm.
Time: 60minutes.
Procedure— Determine the amount of C4H4FN3Odissolved by employing UVabsorption at the wavelength of maximum absorbance at about 276nm on filtered portions of the solution under test,suitably diluted with Dissolution Medium,if necessary,in comparison with a Standard solution having a known concentration of USP Flucytosine RSin the same Medium.
Tolerances— Not less than 80%(Q)of the labeled amount of C4H4FN3Ois dissolved in 60minutes.
Uniformity of dosage units á905ñ: meet the requirements.
Assay— Weigh the contents of not fewer than 20Capsules,and determine the average weight per Capsule.Mix the combined contents,and transfer an accurately weighed portion of the powder,equivalent to about 250mg of flucytosine,to a 250-mLvolumetric flask.Add about 50mLof 0.1Nhydrochloric acid,shake by mechanical means for 30minutes,then add 0.1Nhydrochloric acid to volume,mix,and filter,discarding the first 20mLof the filtrate.Dilute 10mLof the clear filtrate with 0.1Nhydrochloric acid to 250mL.Dilute 10.0mLof this solution with 0.1Nhydrochloric acid to 50mL.Dissolve an accurately weighed quantity of USP Flucytosine RSin 0.1Nhydrochloric acid,and dilute quantitatively and stepwise with the same solvent to obtain a Standard solution having a known concentration of about 8µg per mL.Concomitantly determine the absorbances of both solutions in 1-cm cells at the wavelength of maximum absorbance at about 285nm,with a suitable spectrophotometer,using 0.1Nhydrochloric acid as the blank.Calculate the quantity,in mg,of flucytosine (C4H4FN3O)in the portion of Capsule contents taken by the formula:
31.25C(AU/AS),
in which Cis the concentration,in µg per mL,of USP Flucytosine RSin the Standard solution;and AUand ASare the absorbances of the solution from the Capsule contents and the Standard solution,respectively.
Auxiliary Information— Staff Liaison:Behnam Davani,Ph.D.,MBA,Senior Scientist
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 829
Pharmacopeial Forum:Volume No.29(1)Page 68
Phone Number:1-301-816-8394