Dissolution á711ñ
Medium:
water;900mL.
Apparatus 2:
75rpm.
Time:
45minutes.
Procedure
Determine the amount of C
21H
21ClN
2O
8dissolved from UVabsorption at the wavelength of maximum absorbance at about 274nm on filtered portions of the solution under test,suitably diluted with
Dissolution Medium,if necessary,in comparison with a Standard solution having a known concentration of
USP Demeclocycline Hydrochloride RSin the same
Medium.
Tolerances
Not less than 75%(Q)of the labeled amount of demeclocycline (C21H21ClN2O8)is dissolved in 45minutes.
Loss on drying á731ñ
Dry about 100mg of Capsule contents,accurately weighed,in a capillary-stoppered bottle in vacuum at 60

for 3hours:the material loses not more than 2.0%of its weight,except that if the Capsules contain starch the material loses not more than 8.0%of its weight.
Assay
Mobile phase,Standard preparation,Resolution solution,and Chromatographic system
Prepare as directed in the
Assayunder
Demeclocycline.
Assay preparation
Remove,as completely as possible,the contents of not fewer than 10Capsules,and weigh.Mix,and transfer an accurately weighed portion of the powder,equivalent to about 50mg of demeclocycline hydrochloride (C21H21ClN2O8·HCl),to a 50-mLvolumetric flask,dilute with 0.01Nhydrochloric acid to volume,and mix.Sonicate for 5minutes,and centrifuge for 5minutes.Pass a portion of the supernatant through a suitable filter having a 1.5-µm or finer porosity,and use the clear filtrate as the Assay preparation.
Procedure
Proceed as directed for
Procedurein the
Assayunder
Demeclocycline.Calculate the quantity,in mg,of demeclocycline hydrochloride (C
21H
21ClN
2O
8·HCl)in the portion of Capsule contents taken by the formula:
0.05CE(rU/rS),
in which the terms are as defined therein.