Crotamiton
;)
2-Butenamide,N-ethyl-N-(2-methylphenyl)-.
N-Ethyl-o-crotonotoluidide [483-63-6].
»Crotamiton is a mixture of cisand transisomers containing not less than 97.0percent and not more than 103.0percent of C13H17NO.
Packaging and storage—
Preserve in tight,light-resistant containers.
Identification—
A:
Infrared Absorption á197Fñ.
Solution:
20µg per mL.
Medium:
cyclohexane.
C:
To about 10mLof a saturated solution in water add a few drops of potassium permanganate TS:a brown color is produced,and a brown precipitate is formed on standing.
Specific gravity á841ñ:
between 1.008and 1.011at 20
.
.
Refractive index á831ñ:
between 1.540and 1.543at 20.
.
Residue on ignition á281ñ:
not more than 0.1%.
Bound halogen—
Place 4drops in a 3-mm (ID)test tube,and add calcium oxide to a height of 1cm.Heat the tube in a flame,starting from the top,until the reaction is complete,then ignite for a short time.Transfer the contents to a beaker containing 10mLof water,acidify with nitric acid,and filter.To the filtrate add 0.2mLof silver nitrate solution (1in 60):any opalescence obtained is not more than that obtained from a blank solution treated in the same manner.
Assay—
Transfer about 50mg of Crotamiton,accurately weighed,to a 100-mLvolumetric flask,add cyclohexane to volume,and mix.Transfer 10.0mLof this solution to a 250-mLvolumetric flask,dilute with cyclohexane to volume,and mix.Determine the absorbance of this solution and of a solution of USP Crotamiton RSin the same medium having a known concentration of about 20µg per mLin 1-cm cells at the wavelength of maximum absorbance at about 242nm,with a suitable spectrophotometer,using cyclohexane as the blank.Calculate the quantity,in mg,of C13H17NOin the Crotamiton taken by the formula:
2.5C(AU/AS),
in which Cis the concentration,in µg per mL,of USP Crotamiton RSin the Standard solution;and AUand ASare the absorbances of the assay solution and the Standard solution,respectively.
Auxiliary Information—
Staff Liaison:Behnam Davani,Ph.D.,MBA,Senior Scientist
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 551
Phone Number:1-301-816-8394