» Paroxetine Tablets contain an amount of Paroxetine Hydrochloride equivalent to not less than 90.0 percent and not more than 110.0 percent of the labeled amount of paroxetine (C19H20FNO3).
Packaging and storage Preserve in tight containers, and store at controlled room temperature.
USP Reference standards 11
A: Infrared Absorption 197K
Test specimen Transfer a quantity of finely powdered Tablets, equivalent to about 90 mg of paroxetine, to a suitable flask, add 100 mL of 0.1 N hydrochloric acid, and stir for 1 hour. Transfer the mixture to a separatory funnel, and add 1.5 mL of ammonium hydroxide to make the solution alkaline. Add 100 mL of ethyl ether to the funnel, and shake for 2 minutes. Transfer the organic layer into the necessary number of centrifuge tubes, and centrifuge for 10 minutes. Recombine the clarified extracts, add 1 drop of water and 0.5 mL of hydrochloric acid, stir, and evaporate to dryness under a stream of nitrogen. Dry the residue in an oven at 90 for 1 hour.
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.
Medium: simulated gastric fluid without enzyme; 900 mL.
Apparatus 2: 60 rpm.
Time: 60 minutes.
Determine the amount of C19H20FNO3 dissolved by employing the following method.
Buffer solution and Mobile phase Prepare as directed in the Assay.
Standard stock solution Dissolve an accurately weighed quantity of USP Paroxetine Hydrochloride RS in an amount of methanol not exceeding 5% of the volume of the final solution, and dilute with Medium to obtain a solution having a known concentration of about 0.63 mg per mL.
Standard solution Quantitatively dilute the Standard stock solution with Medium to obtain a solution having a concentration estimated to correspond to that of the filtered solution under test.
Chromatographic system Proceed as directed in the Assay, except to chromatograph the Standard solution.
Procedure Separately inject equal volumes (about 20 µL) of a portion of the solution under test, previously passed through a suitable 0.45-µm membrane filter, and the Standard solution into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity of C19H20FNO3 dissolved based on the peak responses obtained from the solution under test and the Standard solution.
Tolerances Not less than 80% (Q) of the labeled amount of C19H20FNO3 is dissolved in 60 minutes.
Uniformity of dosage units 905: meet the requirements.
procedure for content uniformity
Buffer solution, Mobile phase, and Chromatographic system Proceed as directed in the Assay.
Standard solution Use the Standard preparation, prepared as directed in the Assay.
Test solution Place 1 Tablet in a suitable volumetric flask, and add a volume of a hydrochloric acid solution (7 in 1000), equivalent to about 25% of the flask volume. Allow the Tablet to disintegrate, dilute with methanol to volume, and mix to obtain a solution containing about 0.1 mg of paroxetine per mL. Centrifuge a portion of the solution.
Procedure Proceed as directed in the Assay. Calculate the quantity, in mg, of C19H20FNO3 in the Tablet taken by the formula:
VCS (329.37/365.83)(rU / rS)in which V is the volume of the flask used; CS is the concentration, in mg per mL, of USP Paroxetine Hydrochloride RS in the Standard solution; 329.37 and 365.83 are the molecular weights for paroxetine and paroxetine hydrochloride, respectively; and rU and rS are the peak responses obtained from the Test solution and the Standard solution, respectively.
Buffer solution Prepare a mixture of water, phosphoric acid, and triethylamine (100:0.6:0.3).
Mobile phase Prepare a filtered and degassed mixture of Buffer solution and acetonitrile (7:3). Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard preparation Dissolve an accurately weighed quantity of USP Paroxetine Hydrochloride RS in methanol, and dilute quantitatively, and stepwise if necessary, with methanol to obtain a solution having a known concentration of about 0.1 mg per mL.
Assay preparation Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 100 mg of paroxetine, to a 200-mL volumetric flask, dissolve in and dilute with methanol to volume, and mix. Centrifuge a portion of this solution for 6 minutes. Transfer 20 mL of the supernatant to a 100-mL volumetric flask, dilute with methanol to volume, and mix.
Chromatographic system (see Chromatography 621) The liquid chromatograph is equipped with a 295-nm detector and a 4.6-mm × 3.3-cm column that contains 3-µm packing L7. The flow rate is about 2.0 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the column efficiency is not less than 750 theoretical plates; the tailing factor is not more than 4; and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure Separately inject equal volumes (about 5 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in percent of tablet label claim, of paroxetine (C19H20FNO3) in the portion of Tablets taken by the formula:
100(CS / CU)(329.37/365.83)(rU / rS)in which CS is the concentration, in mg per mL, of USP Paroxetine Hydrochloride RS in the Standard preparation; CU is the nominal concentration of paroxetine, in mg per mL, based on the tablet label claim, in the Assay preparation; 329.37 and 365.83 are the molecular weights for paroxetine and paroxetine hydrochloride, respectively; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.
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USP35NF30 Page 4227Pharmacopeial Forum: Volume No. 33(4) Page 672