Dissolution 
711
—
Medium:
water; 900 mL.
Apparatus 2:
50 rpm.
FOR PRODUCTS LABELED AS 5-MG TABLETS—
Time:
45 minutes.
Determine the amount of C23H36N2O2 dissolved by employing the following method.
Mobile phase—
Prepare a filtered and degassed mixture of acetonitrile and water (29:21). Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Diluting solution—
Prepare a solution of acetonitrile and water (7:3).
Standard solution—
Dissolve an accurately weighed quantity of
USP Finasteride RS in
Diluting solution, and dilute quantitatively, and stepwise if necessary, with
Diluting solution to obtain a solution having a known concentration approximately equivalent to the sample under test.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 220-nm detector and a 4.6-mm × 5-cm column that contains packing L1. The column temperature is maintained at 45
. The flow rate is about 2 mL per minute. Chromatograph the
Standard solution, and record the peak responses as directed for
Procedure: the capacity factor,
k¢, is not less than 2.0; the column efficiency is not less than 1000 theoretical plates; the tailing factor is not more than 2.0; and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 200 µL) of the solution under test and the Standard solution into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity of C23H36N2O2 dissolved.
Tolerances—
Not less than 75% (Q) of the labeled amount of C23H36N2O2 is dissolved in 45 minutes.
FOR PRODUCTS LABELED AS 1-MG TABLETS—
Time:
30 minutes.
Mobile phase—
Prepare a degassed mixture of acetonitrile and water (11:9). Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Diluting solution—
Prepare a solution of water and acetonitrile (7:3).
Standard solution—
Dissolve an accurately weighed quantity of
USP Finasteride RS in
Diluting solution, to obtain a solution having a known concentration of 0.1 mg per mL. Dilute this solution quantitatively, and stepwise if necessary, in 0.5% sodium lauryl sulfate to obtain a solution containing 0.001 mg of finasteride per mL.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 220-nm detector and a 4.6-mm × 15-cm column that contains 5-µm packing L11. The column temperature is maintained at 45
. The flow rate is about 1.5 mL per minute. Chromatograph the
Standard solution, and record the peak responses as directed for
Procedure: the column efficiency is not less than 5000 theoretical plates; the tailing factor is not more than 2.0; and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 100 µL) of the solution under test and the Standard solution into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity of finasteride (C23H36N2O2) dissolved.
Tolerances—
Not less than 80% (Q) of the labeled amount of C23H36N2O2 is dissolved in 30 minutes.
Assay—
Mobile phase—
Prepare a filtered and degassed mixture of 2.5 mM phosphoric acid and acetonitrile (1:1). Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Diluting solution—
Prepare a solution of acetonitrile and water (7:3).
Standard preparation—
Dissolve an accurately weighed quantity of
USP Finasteride RS in
Diluting solution, and dilute quantitatively, and stepwise if necessary, with
Diluting solution to obtain a solution having a known concentration of about 100 µg per mL.
Assay preparation—
Weigh and finely powder not fewer than 20 Tablets. Transfer an amount of powder equivalent to about 10 mg of finasteride, accurately weighed, to a 100-mL volumetric flask, dissolve in and dilute with Diluting solution to volume, and mix.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 240-nm detector and a 4.6-mm × 10.0-cm column that contains packing L1. The column temperature is maintained at 45
. The flow rate is about 1.5 mL per minute. Chromatograph the
Standard preparation, and record the peak responses as directed for
Procedure: the capacity factor,
k¢, is not less than 2.0; the column efficiency is not less than 1000 theoretical plates; the tailing factor is not more than 2.0; and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 20 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 mg, of finasteride (C
23H
36N
2O
2) in the portion of Tablets taken by the formula:
100C(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Finasteride RS in the
Standard preparation; and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
