Identification—
Shake a portion of Capsule contents,equivalent to about 100mg of gemfibrozil,with 10mLof 0.1Nsodium hydroxide.Filter the mixture into a 50-mLcentrifuge tube,and acidify the filtrate with 3Nsulfuric acid to obtain a copious precipitate.Centrifuge,and discard the clear solution.Wash the precipitate with small portions of water,and allow it to air-dry:the IRabsorption spectrum of a potassium bromide dispersion of the precipitate,previously dried over silica gel for 4hours,exhibits maxima only at the same wavelengths as those of a similar preparation of
USP Gemfibrozil RS.
Dissolution á711ñ—
Medium:
0.2MpH7.5phosphate buffer,prepared as directed under
Solutionsin the section
Reagents,Indicators,and Solutions,except that 0.8Mmonobasic potassium phosphate solution and 0.8Msodium hydroxide solution are used;900mL.
Apparatus 2:
50rpm.
Time:
45minutes.
Procedure—
Determine the amount of C
15H
22O
3dissolved from UVabsorbances at the wavelength of maximum absorbance at about 276nm of filtered portions of the solution under test,suitably diluted with 1Nsodium hydroxide,in comparison with a Standard solution obtained as follows.Prepare a standard stock solution of
USP Gemfibrozil RShaving a known concentration of about 0.33mg per mLin
Medium.[NOTE—Initially dissolve the Reference Standard in an amount of methanol not to exceed 1%of the volume of the standard stock solution.
]Dilute the standard stock solution quantitatively with 1Nsodium hydroxide to obtain a Standard solution having a concentration estimated to correspond to that of the filtered and diluted solution under test.
Tolerances—
Not less than 80%(Q)of the labeled amount of C15H22O3is dissolved in 45minutes.
Assay—
Mobile phase,Standard preparation,and System suitability preparation—
Proceed as directed in the Assayunder Gemfibrozil.
Assay preparation—
Remove,as completely as possible,the contents of not less than 20Capsules,weigh,and mix.Transfer an accurately weighed portion of the powder,equivalent to about 100mg of gemfibrozil,to a 100-mLvolumetric flask,add about 80mLof methanol,and shake to dissolve.Dilute with methanol to volume,mix,and filter.Transfer 5.0mLof this clear solution to a 25-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.
Procedure—
Proceed as directed for
Procedurein the
Assayin
Gemfibrozil.Calculate the quantity,in mg,of C
15H
22O
3in the portion of Capsules taken by the formula:
500C(rU/rS),
in which the terms are as defined therein.