Methotrexate Injection
»Methotrexate Injection is a sterile solution of Methotrexate in Water for Injection prepared with the aid of Sodium Hydroxide.It contains not less than 90.0percent and not more than 110.0percent of the labeled amount of methotrexate (C20H22N8O5).
Packaging and storage— Preserve in single-dose or in multiple-dose containers,preferably of Type Iglass,protected from light.
Identification— Dilute,if necessary,a volume of Injection,equivalent to about 25mg of methotrexate,with water to obtain a solution having a concentration of about 2.5mg per mL.Adjust with 0.1Nhydrochloric acid to a pHof 4.0.Place the slurry in a 50-mLcentrifuge tube,and centrifuge.Decant the supernatant,add 25mLof acetone,shake,and filter through a solvent-resistant,membrane filter of 0.45-µm pore size.Air-dry the filtered precipitate:the methotrexate so obtained responds to Identificationtest Aunder Methotrexate.
Bacterial endotoxins á85ñ— It contains not more than 0.4USP Endotoxin Unit per mg of methotrexate sodium.
pHá791ñ: between 7.0and 9.0.
Other requirements— It meets the requirements under Injections á1ñ.
Assay—
pH6.0Buffer solution ,Mobile phase,System suitability preparation,System suitability test,and Standard preparation—Proceed as directed in the Assayunder Methotrexate.
Assay preparation— Transfer an accurately measured volume of Injection,equivalent to about 25mg of methotrexate,to a 250-mLvolumetric flask,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 each mLof the Injection taken by the formula:
250(C/V)(PU/PS),
in which Cis the concentration,in mg per mL,of USP Methotrexate RSin the Standard preparation;Vis the volume,in mL,of Injection taken;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 1249
Phone Number:1-301-816-8389