Phentolamine Mesylate for Injection
»Phentolamine Mesylate for Injection is sterile Phentolamine Mesylate or a sterile mixture of Phentolamine Mesylate with a suitable buffer or suitable diluents.It contains not less than 90.0percent and not more than 110.0percent of the labeled amount of C17H19N3O·CH4O3S.
Packaging and storage— Preserve in Containers for Sterile Solidsas described under Injections á1ñ.
Constituted solution— At the time of use,it meets the requirements for Constituted Solutionsunder Injections á1ñ.
Identification— Mix a portion of it,equivalent to about 40mg of phentolamine mesylate,with about 15mLof chloroform.Filter into a beaker,and evaporate to dryness,taking precautions against introducing moisture:the residue so obtained responds to Identificationtest Aunder Phentolamine Mesylate.
Bacterial endotoxins á85ñ— It contains not more than 5.8USP Endotoxin Units per mg of phentolamine mesylate.
Uniformity of dosage units á905ñ: meets the requirements.
Procedure for content uniformity— Dissolve the contents of 1container in water to provide a solution containing about 20µg of phentolamine mesylate per mL.Concomitantly determine the absorbances of this solution and of a solution of USP Phentolamine Mesylate RS,in the same medium,at a concentration of about 20µg per mL,in 1-cm cells at the wavelength of maximum absorbance at about 278nm,with a suitable spectrophotometer,using water as the blank.Calculate the quantity,in mg,of C17H19N3O·CH4O3Sin the Phentolamine Mesylate for Injection taken by the formula:
(T/D)C(AU/AS),
in which Tis the labeled quantity,in mg,of phentolamine mesylate in the Phentolamine Mesylate for Injection,Dis the concentration,in µg per mL,of phentolamine mesylate in the solution from the Phentolamine Mesylate for Injection,based on the labeled quantity per container and the extent of dilution,Cis the concentration,in µg per mL,of USP Phentolamine Mesylate RSin the Standard solution,and AUand ASare the absorbances of the solution from the Phentolamine Mesylate for Injection and the Standard solution,respectively.
pHá791ñ: between 4.5and 6.5,in a freshly prepared solution having a concentration of about 1in 100.
Other requirements— It meets the requirements for Sterility Tests á71ñand Labelingunder Injections á1ñ.
Assay—
Standard preparation— Transfer about 25mg of USP Phentolamine Mesylate RS,accurately weighed,to a 50-mLvolumetric flask,add water to volume,and mix.
Assay preparation— Dissolve the contents of 10containers of Phentolamine Mesylate for Injection in a volume of water corresponding to the volume of solvent specified in the labeling.Transfer an aliquot,equivalent to about 25mg of phentolamine mesylate,to a 50-mLvolumetric flask,add water to volume,and mix.
Procedure— Pipet 5-mLportions,respectively,of the Standard preparation,Assay preparation,and water to provide a blank,into separate 125-mLseparators.Into each separator pipet 5-mLportions of 0.1Nhydrochloric acid and saturated picric acid solution.Extract with three 25-mLportions of chloroform,filtering each portion through chloroform-washed cotton into a 100-mLvolumetric flask.Dilute with chloroform to volume,and mix.Concomitantly determine the absorbances of the solutions from the Assay preparationand the Standard preparationin 1-cm cells at the wavelength of maximum absorbance at about 410nm,with a suitable spectrophotometer,against the blank.Calculate the quantity,in mg,of C17H19N3O·CH4O3Sin the aliquot of Phentolamine Mesylate for Injection taken by the formula:
50C(AU/AS),
in which Cis the concentration,in mg per mL,of USP Phentolamine Mesylate RSin the Standard preparation,and AUand ASare the absorbances of the solutions from the Assay preparationand the Standard preparation,respectively.
Auxiliary Information— Staff Liaison:Andrzej Wilk,Ph.D.,Senior Scientific Associate
Expert Committee:(PA5)Pharmaceutical Analysis 5
USP28–NF23Page 1537
Phone Number:1-301-816-8305