Finasteride
(fin as' ter ide).
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372.554-Azaandrost-1-ene-17-carboxamide, N-(1,1-dimethylethyl)-3-oxo-, (5
,17
)-.
N-tert-Butyl-3-oxo-4-aza-5
-androst-1-ene-17-carboxamide
[98319-26-7].» Finasteride contains not less than 98.5 percent and not more than 101.0 percent of C23H36N2O2, calculated on the anhydrous basis.
Packaging and storage—
Preserve in tight containers, and store at controlled room temperature.
USP Reference standards 
11
—
11—
USP Finasteride RS 
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Identification—
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.
Specific rotation 781S:
between 
56.0
and 60.0, determined at 405 nm.
781S:
between 56.0 and 60.0, determined at 405 nm.
Test solution:
10 mg per mL, in methanol.
Water, Method I 921:
not more than 0.3%.
921:
not more than 0.3%.
Residue on ignition 281:
not more than 0.1%.
281:
not more than 0.1%.
Heavy metals, Method II 231:
0.001%.
231:
0.001%.
Chromatographic purity—
Mobile phase—
Prepare a filtered and degassed mixture of water, tetrahydrofuran, and acetonitrile (8:1:1). Make adjustments if necessary (see System Suitability under Chromatography 621).
621).
Diluting solution—
Prepare a solution of water and acetonitrile (1:1).
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 of about 1.0 mg per mL.
Test solution—
Transfer about 100 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 210-nm detector and a 4.6-mm × 30-cm column that contains 4-µm packing L1. The flow rate is about 1.5 mL per minute. The column temperature is maintained at 60. Chromatograph the Standard solution, and record the peak responses as directed for Procedure: the column efficiency is not less than 10,000 theoretical plates; and the tailing factor is not more than 1.3.
621)—
The liquid chromatograph is equipped with a 210-nm detector and a 4.6-mm × 30-cm column that contains 4-µm packing L1. The flow rate is about 1.5 mL per minute. The column temperature is maintained at 60. Chromatograph the Standard solution, and record the peak responses as directed for Procedure: the column efficiency is not less than 10,000 theoretical plates; and the tailing factor is not more than 1.3.
Procedure—
Inject a volume (about 15 µL) of the Test solution into the chromatograph, record the chromatograms, and measure the peak responses. Calculate the percentage of each impurity in the portion of Finasteride taken by the formula:
100(ri / rs)
in which ri is the peak response for each impurity, and rs is the sum of the responses of all peaks: not more than 0.5% of any individual impurity is found; and not more than 1.0% of total impurities is found.
Assay—
Mobile phase—
Prepare a filtered and degassed mixture of water and tetrahydrofuran (4:1). Make adjustments if necessary (see System Suitability under Chromatography 621).
621).
Diluting solution—
Prepare a solution of water and acetonitrile (1:1).
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 200 µg per mL.
Assay preparation—
Transfer about 20 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 215-nm detector and a 3.0-mm × 3.0-cm column that contains 3-µm packing L7. The flow rate is about 3 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the column efficiency is not less than 1800 theoretical plates; the tailing factor is not more than 1.3; and the relative standard deviation for replicate injections is not more than 1.0%.
621)—
The liquid chromatograph is equipped with a 215-nm detector and a 3.0-mm × 3.0-cm column that contains 3-µm packing L7. The flow rate is about 3 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the column efficiency is not less than 1800 theoretical plates; the tailing factor is not more than 1.3; and the relative standard deviation for replicate injections is not more than 1.0%.
Procedure—
Separately inject equal volumes (about 10 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 C23H36N2O2 in the portion of Finasteride 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.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Domenick Vicchio, Ph.D.
Senior Scientific Liaison 1-301-998-6828 |
(SM42010) Monographs - Small Molecules 4 |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 3196
Pharmacopeial Forum: Volume No. 27(2) Page 2144