Packaging and storage— Preserve in tight containers.

USP Reference standards á11ñ— USP Tolnaftate RS.

Identification— Evaporate 10mLof the next-to-final chloroform solution prepared in the Assayon a steam bath just to dryness,and dissolve the residue in 1mLof alcohol.Using this as the test solution,proceed as directed in Identificationtest Cunder Tolnaftate:the specified result is observed.

Minimum fill á755ñ: meets the requirements.

Assay— Transfer a portion of Cream,equivalent to about 10mg of tolnaftate and accurately weighed,to a 250-mLseparator containing about 75mLof chloroform.Wash the chloroform solution successively with two 25-mLportions of 0.1Nsodium hydroxide,two 25-mLportions of 0.1Nhydrochloric acid,and 25mLof water.Filter the chloroform layer through a chloroform-washed cotton pledget into a 100-mLvolumetric flask.Add chloroform to volume,and mix.[NOTE—Reserve a 10-mLportion of this solution for the Identificationtest.]Dilute 5.0mLof the solution with chloroform to 50.0mL,and mix.Dissolve an accurately weighed quantity of USP Tolnaftate RSin chloroform,and dilute quantitatively and stepwise with chloroform to obtain a Standard solution having a known concentration of about 10µg per mL.Concomitantly determine the absorbances of both solutions in 1-cm cells at the wavelength of maximum absorbance at about 258nm,with a suitable spectrophotometer,using chloroform as the blank.Calculate the quantity,in mg,of C19H17NOSin the portion of Cream taken by the formula: in which Cis the concentration,in µg per mL,of USP Tolnaftate RSin the Standard solution,and AUand ASare the absorbances of the solution from the Cream and the Standard solution,respectively.

Expert Committee:(PA7)Pharmaceutical Analysis 7

USP28–NF23Page 1951

Phone Number:1-301-816-8394