Ethionamide
;)
4-Pyridinecarbothioamide,2-ethyl-.
2-Ethylthioisonicotinamide [536-33-4].
»Ethionamide contains not less than 98.0percent and not more than 102.0percent of C8H10N2S,calculated on the anhydrous basis.
Packaging and storage—
Preserve in tight containers.
Identification—
A:
Infrared Absorption á197Kñ.
B:
Ultraviolet Absorption á197Uñ—Test solution versus standard solution,prepared as directed in the Assay.
and 164
pHá791ñ:
between 6.0and 7.0,in a 1in 100slurry in water.
Water,Method Iá921ñ:
not more than 2.0%.
Residue on ignition á281ñ:
not more than 0.2%.
Selenium á291ñ:
0.003%,a 200-mg test specimen being used.
Organic volatile impurities,Method Vá467ñ:
meets the requirements.
Solvent—
Use dimethyl sulfoxide.
Assay—
Transfer about 100mg of Ethionamide,accurately weighed,to a 250-mLvolumetric flask,dissolve in about 100mLof methanol,dilute with methanol to volume,and mix.Transfer a 5-mLaliquot to a 200-mLvolumetric flask,dilute with methanol to volume,and mix (test solution).Dissolve a suitable quantity of USP Ethionamide RS,accurately weighed,in methanol,and dilute quantitatively and stepwise with methanol 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 290nm,with a suitable spectrophotometer,using methanol as the blank.Calculate the quantity,in mg,of C8H10N2Sin the portion of Ethionamide taken by the formula:
10C(AU/AS),
in which Cis the concentration,in µg per mL,of USP Ethionamide RSin the Standard solution,calculated on the anhydrous basis,and AUand ASare the absorbances of the test 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 790
Phone Number:1-301-816-8394