Identification—
A:
Ultraviolet Absorption 
197U
—
Test solution—
Use the solution under test as obtained in the Buffer stage of the Drug release test.
Standard solution—
Use the Standard solution prepared as directed in the Buffer stage of the Drug release test.
B:
The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.
Drug release, Method B 724—
ACID STAGE—
Acid stage medium:
0.1 N hydrochloric acid; 1000 mL.
Apparatus 2:
50 rpm.
Time:
2 hours.
Procedure—
Determine the amount of C
14H
14O
3 dissolved by employing UV absorption at the wavelength of maximum absorbance at about 332 nm on filtered portions of the solution under test, suitably diluted with
Acid stage medium, if necessary, in comparison with a Standard solution having a known concentration of
USP Naproxen RS in the same
Acid stage medium.
Tolerances—
Not more than 10% of the labeled amount of C14H14O3 is dissolved in 2 hours.
BUFFER STAGE—
Buffer stage medium:
0.2 M phosphate buffer, pH 6.8; 1000 mL.
Apparatus 2:
50 rpm.
Time:
45 minutes.
Procedure—
Determine the amount of C
14H
14O
3 dissolved by employing UV absorption at the wavelength of maximum absorbance at about 332 nm on filtered portions of the solution under test, suitably diluted with
Buffer stage medium, if necessary, in comparison with a Standard solution having a known concentration of
USP Naproxen RS in the same
Buffer stage medium.
Tolerances—
Not less than 80% (Q) of the labeled amount of C14H14O3 is dissolved in 45 minutes.
Uniformity of dosage units 905:
meets the requirements.
PROCEDURE FOR CONTENT UNIFORMITY—
Mobile phase, Diluent A, Diluent B, and Chromatographic system—
Proceed as directed in the Assay.
Standard solution—
Transfer about 12.5 mg of
USP Naproxen RS, accurately weighed, to a 50-mL volumetric flask, dilute with
Diluent A to volume, and mix well. Transfer 10-mL of this solution to a 25-mL volumetric flask, dilute with
Diluent B to volume, and mix.
Test solution—
Transfer 1 Tablet to a 200-mL volumetric flask, and add about 140 mL of Diluent B. Shake by mechanical means for 15 minutes, sonicate for 15 minutes, dilute with Diluent B to volume, and mix. Pass a portion of this solution through a 0.45-µm filter, pipet 2.0 mL of the filtrate for a 500-mg tablet and 2.5-mL for a 375-mg tablet into a 50-mL volumetric flask, and dilute with Mobile phase to volume.
Assay—
Mobile phase—
Prepare a filtered and degassed mixture of 1% acetic acid solution and acetonitrile (11:9).
Diluent A—
Use acetonitrile and water (9:1).
Diluent B—
Use acetonitrile and water (1:1).
Standard stock preparation—
Transfer about 12.5 mg of
USP Naproxen RS, accurately weighed, to a 25-mL volumetric flask. Dissolve in and dilute with
Diluent A to volume, and mix.
Standard preparation—
Accurately transfer 10.0 mL of the Standard stock preparation into a 50-mL volumetric flask, and dilute with Mobile phase to volume.
Assay preparation—
Weigh and powder 20 Tablets. Accurately weigh an amount of the powder, equivalent to about 250 mg of naproxen, into a 100-mL volumetric flask, and add about 70 mL of Diluent B. Shake by mechanical means for 15 minutes, sonicate for 15 minutes, dilute with Diluent B to volume, and mix. Pass this solution through a 0.45-µm filter, transfer 2.0 mL of the filtrate into a 50-mL volumetric flask, and dilute with Mobile phase to volume.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm × 25-cm column that contains 5-µm packing L1. The flow rate is about 1.0 mL per minute. Chromatograph the
Standard preparation, and record the peak responses as directed for
Procedure: the tailing factor of the naproxen peak is not more than 1.5, and the relative standard deviation for replicate injections of the
Standard preparation is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 50 µL) of the
Standard preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the naproxen peak. Calculate the quantity, in mg, of naproxen (C
14H
14O
3) in the portion of Tablets taken by the formula:
2500C(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Naproxen RS in the
Standard preparation; and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
