Methotrexate Tablets
»Methotrexate Tablets contain not less than 90.0percent and not more than 110.0percent of the labeled amount of methotrexate (C20H22N8O5).
Packaging and storage— Preserve in well-closed containers.Aunit-of-use container contains a quantity of Tablets sufficient to provide one week's therapy as indicated in the labeling.
Labeling— When packaged in a unit-of-use container,the label indicates the total amount of methotrexate present as one week's supply.
Identification— Dissolve 1Tablet in 100mLof dilute hydrochloric acid (1in 100),and filter the solution:the UVabsorption spectrum of the filtrate exhibits maxima and minima at the same wavelengths as that of a solution containing about 2.5mg of USP Methotrexate RSin 100mLof dilute hydrochloric acid (1in 100).
Dissolution á711ñ—
Medium: 0.1Nhydrochloric acid;900mL.
Apparatus 2: 50rpm.
Time: 45minutes.
Procedure— Determine the amount of C20H22N8O5dissolved from UVabsorbances at the wavelength of maximum absorbance at about 306nm of filtered portions of the solution under test,suitably diluted with Dissolution Medium,in comparison with a Standard solution having a known concentration of USP Methotrexate RSin the sameMedium.
Tolerances— Not less than 75%(Q)of the labeled amount of C20H22N8O5is dissolved in 45minutes.
Uniformity of dosage units á905ñ: meet the requirements.
Assay—
pH6.0Buffer solution ,Mobile phase,System suitability preparation,System suitability test,and Standard preparation—Proceed as directed in the Assayunder Methotrexate.
Assay preparation— Weigh and finely powder not less than 20Tablets.Weigh accurately a portion of the powder,equivalent to about 25mg of methotrexate,and transfer to a 250-mLvolumetric flask.Add about 200mLof Mobile phase,and dissolve the methotrexate using a mechanical shaker or ultrasonic bath.Dilute with Mobile phaseto volume,and mix.
Procedure— Proceed as directed for Procedurein the Assayunder Methotrexate.Calculate the quantity,in mg,of methotrexate (C20H22N8O5)in the portion of Tablets taken by the formula:
250C(PU/PS),
in which Cis the concentration,in mg per mL,of USP Methotrexate RSin the Standard preparation;and PUand PSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.
Auxiliary Information— Staff Liaison:Lawrence Evans,III,Ph.D.,Scientist
Expert Committee:(PA6)Pharmaceutical Analysis 6
USP28–NF23Page 1250
Phone Number:1-301-816-8389