Spironolactone
C24H32O4S 416.57
Pregn-4-ene-21-carboxylic acid, 7-(acetylthio)-17-hydroxy-3-oxo-,
-lactone, (7
,17)-;
17-Hydroxy-7-mercapto-3-oxo-17-pregn-4-ene-21-carboxylic acid -lactone acetate
[52-01-7].
197K
USP35
781S:
41
to 45USP35
(spir on'' oh lak' tone).
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C24H32O4S 416.57
Pregn-4-ene-21-carboxylic acid, 7-(acetylthio)-17-hydroxy-3-oxo-,
-lactone, (7,17)-;
17-Hydroxy-7
-mercapto-3-oxo-17-pregn-4-ene-21-carboxylic acid -lactone acetate
[52-01-7].DEFINITION
Spironolactone contains NLT 97.0% and NMT 103.0% of C24H32O4S, calculated on the dried basis.
IDENTIFICATION
Change to read:
• A. Infrared Absorption 197KUSP35
• B. Ultraviolet Absorption 197U
197U
Sample solution:
10 µg/mL in methanol
Analytical wavelength:
238 nm
Acceptance criteria:
Absorptivities, calculated on the dried basis, do not differ by more than 3.0%.
• C.
Sample solution:
Add 100 mg to a mixture of 10 mL of water and 2 mL of 1 N sodium hydroxide.
Analysis:
Boil the mixture for 3 min, cool, and add 1 mL of glacial acetic acid and 1 mL of lead acetate TS.
Acceptance criteria:
A brown-to-black precipitate of lead sulfide is formed.
ASSAY
• Procedure
Mobile phase:
Methanol and water (60:40)
Standard solution:
0.5 mg/mL of USP Spironolactone RS in a mixture of acetonitrile and water (1:1)
Sample solution:
0.5 mg/mL of Spironolactone in a mixture of acetonitrile and water (1:1)
Chromatographic system
Mode:
LC
Detector:
UV 230 nm
Column:
4.6-mm × 15-cm; packing L1
Flow rate:
1 mL/min
Injection size:
20 µL
System suitability
Sample:
Standard solution
Suitability requirements
Tailing factor:
NMT 2.0
Relative standard deviation:
NMT 1.5%
Analysis
Samples:
Standard solution and Sample solution
Calculate the percentage of spironolactone (C24H32O4S) in the portion of sample taken:
Result = (rU/rS) × (CS/CU) × 100
| rU | = | = peak response from the Sample solution |
| rS | = | = peak response from the Standard solution |
| CS | = | = concentration of USP Spironolactone RS in the Standard solution (mg/mL) |
| CU | = | = concentration of Spironolactone in the Sample solution (mg/mL) |
Acceptance criteria:
97.0%–103.0% on the dried basis
IMPURITIES
• Limit of Mercapto Compounds
Sample solution:
Shake 2.0 g with 30 mL of water, and filter.
Analysis:
To 15 mL of the filtrate add 3 mL of starch TS, and titrate with 0.010 N iodine. Perform a blank determination, and make any necessary correction.
Acceptance criteria:
NMT 0.10 mL of 0.010 N iodine is consumed.
• Ordinary Impurities 466
466
Standard solution:
Chloroform
Test solution:
Chloroform
Eluant:
Butyl acetate
Visualization:
5
SPECIFIC TESTS
Change to read:
• Optical Rotation, Specific Rotation 781S:
41 to 45USP35
Sample solution:
10 mg/mL in alcoholUSP35
alcoholUSP35
• Loss on Drying 731:
Dry a sample at 105 for 2 h: it loses NMT 0.5% of its weight.
731:
Dry a sample at 105 for 2 h: it loses NMT 0.5% of its weight.
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in well-closed containers.
• USP Reference Standards 11
11
USP Spironolactone RS 
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Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Sujatha Ramakrishna, Ph.D.
Senior Scientific Liaison 1-301-816-8349 |
(SM22010) Monographs - Small Molecules 2 |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 4680
Pharmacopeial Forum: Volume No. 37(1)