Spironolactone and Hydrochlorothiazide Tablets

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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1 DEFINITION

Spironolactone and Hydrochlorothiazide Tablets contain NLT 90.0% and NMT 110.0% of the labeled amounts of spironolactone (C₂₄H₃₂O₄S) and hydrochlorothiazide (C₇H₈ClN₃O₄S₂).

2 IDENTIFICATION

A. The retention times of the major peaks of the Sample solution correspond to those of the Standard solution, as obtained in the Assay. Add the following:

B. The UV spectra of the major peaks of the Sample solution correspond to those of the Standard solution, as obtained in the Assay. (USP 1- Dec-2023)

3 ASSAY

Change to read:

PROCEDURE

Protect all solutions containing spironolactone and hydrochlorothiazide from light. Solution A: Methanol and water (10:90)

Solution B: Methanol Mobile phase: See Table 1.

Table 1

Diluent: Acetonitrile and water (50:50)

System suitability stock solution: 50 μg/mL each of USP Spironolactone Related Compound A RS and USP Benzothiadiazine Related Compound A RS in Diluent. Sonicate to dissolve if necessary.

System suitability solution: 0.1 mg/mL each of USP Spironolactone RS and USP Hy drochlorothiazide RS, and 1 µg/mL each of USP

Spironolactone Related Compound A RS and USP Benzothiadiazine Related Compound A RS in Diluent prepared as follows. Transfer an appropriate amount of USP Spironolactone RS and USP Hy drochlorothiazide RS to a suitable volumetric flask. Add a suitable portion of the System suitability stock solution and dilute with Diluent to volume.

Standard solution: 0.1 mg/mL each of USP Spironolactone RS and USP Hy drochlorothiazide RS in Diluent. Sonicate to dissolve if necessary. Sample stock solution: Nominally 0.5 mg/mL each of spironolactone and hydrochlorothiazide from Tablets prepared as follows. Transfer

Tablets (NLT 10) to a suitable volumetric flask. Add Diluent to about 60% of the flask volume, sonicate for about 10 min, and maintain a cool sonication bath temperature. Shake for about another 30 min and allow to cool to room temperature. Dilute with Diluent to volume. Sample solution: Nominally 0.1 mg/mL each of spironolactone and hydrochlorothiazide from the Sample stock solution prepared as follows.

Transfer 10.0 mL of the Sample stock solution to a 50-mL volumetric flask. Dilute with Diluent to volume. Pass a portion through a suitable filter of 0.45-µm pore size and discard the first 4 mL of the filtrate.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.) Mode: LC

Detector: UV 254 nm. For Identification B, use a diode array detector in the range of 190–400 nm.

Column: 4.6-mm × 15-cm; 2.7-µm packing L1

Temperatures Autosampler: 5°

Column: 40°

Flow rate: 1.2 mL/min

Injection volume: 10 µL

System suitability

Samples: System suitability solution and Standard solution

[NOTE—The relative retention times for benzothiadiazine related compound A, hydrochlorothiazide, spironolactone, and spironolactone related compound A are 0.7, 1.0, 4.0, and 4.4, respectively.]

Suitability requirements

Resolution: NLT 2.0 between benzothiadiazine related compound A and hydrochlorothiazide; NLT 2.0 between spironolactone and spironolactone related compound A, System suitability solution

Tailing factor: NMT 2.0 for hydrochlorothiazide and spironolactone, Standard solution

Relative standard deviation: NMT 1.0% for hydrochlorothiazide and spironolactone, Standard solution (USP 1-Dec-2023)

Analysis

Samples: Standard solution and Sample solution

Calculate the percentages of the labeled amounts (USP 1-Dec-2023) of spironolactone (C₂₄H₃₂O₄S) and hydrochlorothiazide (C₇H₈ClN₃O₄S₂) in the portion of Tablets taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of spironolactone or hydrochlorothiazide from the Sample solution

r_S = peak response of spironolactone or hydrochlorothiazide from the Standard solution

C_S = concentration of USP Spironolactone RS or USP Hydrochlorothiazide RS in the Standard solution (mg/mL)

C_U = nominal concentration of spironolactone or hydrochlorothiazide in the Sample solution (mg/mL)

Acceptance criteria: 90.0%–110.0%

4 PERFORMANCE TESTS

Change to read:

DISSOLUTION 〈711〉

Medium: 0.1 N hydrochloric acid containing 0.1% sodium dodecyl sulfate; 900 mL

Apparatus 2: 75 rpm

Time: 60 min

Solution A: Acetonitrile

Solution B: 4.5 g/L of monobasic potassium phosphate in water Mobile phase: See Table 2.

Table 2

Standard solution: 12.5 µg/mL each of USP Spironolactone RS and USP Hydrochlorothiazide RS in a mixture of methanol and Medium (50:50) (USP 1-Dec-2023)

Sample solution: Transfer a 5.0-mL portion of the solution under test to a 10-mL volumetric flask, and dilute with methanol to volume.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 254 nm

Column: 4.6-mm × 25-cm; 10-µm (USP 1-Dec-2023) packing L1

Flow rate: 1 mL/min

Injection volume: 20 µL System suitability

Sample: Standard solution

[NOTE—The relative retention times for hydrochlorothiazide and spironolactone are 0.5 and 1.0, respectively.] Suitability requirements

Resolution: NLT 2.0 between hydrochlorothiazide and spironolactone

Relative standard deviation: NMT 2.0% each for hydrochlorothiazide and spironolactone (USP 1-Dec-2023)

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amounts of spironolactone (C₂₄H₃₂O₄S) and hydrochlorothiazide (C₇H₈ClN₃O₄S₂) dissolved:

Result = (r_U/r_S) × C_S × V × D × (1/L) × 100

r_U = peak response of spironolactone or hydrochlorothiazide from the Sample solution

r_S = peak response of spironolactone or hydrochlorothiazide from the Standard solution

C_S = concentration of USP Spironolactone RS or USP Hydrochlorothiazide RS in the Standard solution (mg/mL)

V = volume of Medium, 900 mL

D = dilution factor for the Sample solution

L = label claim of spironolactone or hydrochlorothiazide (mg/Tablet)

(USP 1-Dec-2023)

Tolerances: NLT 75% (Q ) each of the labeled amounts of spironolactone (C₂₄H₃₂O₄S) and hydrochlorothiazide (C₇H₈ClN₃O₄S₂) is dissolved.

Change to read:

UNIFORMITY OF DOSAGE UNITS 〈905〉: Meet the requirements (USP 1-Dec-2023)

Add the following:

5 IMPURITIES

ORGANIC IMPURITIES

Protect all solutions containing spironolactone and hydrochlorothiazide from light.

Solution A, Solution B, Diluent, System suitability stock solution, and System suitability solution: Prepare as directed in the Assay. Mobile phase: See Table 3.

Table 3

Sensitivity solution: 0.5 µg/mL of USP Hydrochlorothiazide RS in Diluent. Sonicate to dissolve if necessary. Standard stock solution: Use Standard solution from the Assay.

Standard solution: 5 µg/mL each of USP Benzothiadiazine Related Compound A RS, USP Spironolactone Related Compound A RS, USP Spironolactone RS, and USP Hy drochlorothiazide RS in Diluent prepared as follows. Transfer a suitable portion of the Standard stock solution to a suitable volumetric flask. Add a suitable portion of the System suitability stock solution and dilute with Diluent to volume.

Sample solution: Nominally 500 µg/mL each of spironolactone and hydrochlorothiazide in Diluent, prepared as follows. Transfer a portion of finely powdered Tablets (NLT 20), equivalent to 250 mg each of spironolactone and hydrochlorothiazide, to a suitable volumetric flask. Add Diluent to about 60% of the flask volume, sonicate for about 10 min, and maintain a cool sonication bath temperature. Shake for about another 30 min and dilute with Diluent to volume. Pass a portion through a suitable filter of 0.2-µm pore size and discard the first 4 mL of the filtrate. [NOTE—It is recommended to store the Sample solution in a refrigerator and use within 6 h.]

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 254 nm

Columns

Guard: 2.1-mm × 5-mm; 1.6-µm packing L1 Analytical: 2.1-mm × 15-cm; 1.6-µm packing L1

Temperatures Autosampler: 5°

Column: 40°

Flow rate: 0.3 mL/min

Injection volume: 2 µL

System suitability

Samples: System suitability solution, Sensitivity solution, and Standard solution

[NOTE—The relative retention times in Table 4 are provided as information that could aid in peak assignment.]

Table 4

^a (2’R)-7α-(Acetylthio)-5’H-spiro[androst-4-ene-17,2’-furan]-3,5’-dione.

^b (2’R)-3’,4’-Dihydro-5’H-spiro[androst-4-ene-17,2’-furan]-3,5’-dione.

^c (2’R)-7β-(Acetylthio)-3’,4’-dihydro-5’H-spiro[androst-4-ene-17,2’-furan]-3,5’-dione.

^d (2’R)-7α-(Acetyldisulfanyl)-3’,4’-dihydro-5’H-spiro[androst-4-ene-17,2’-furan]-3,5’-dione.

Suitability requirements

Resolution: NLT 2.0 between benzothiadiazine related compound A and hydrochlorothiazide; NLT 2.0 between spironolactone and

spironolactone related compound A, System suitability solution

Relative standard deviation: NMT 5.0% each for benzothiadiazine related compound A, hydrochlorothiazide, spironolactone, and spironolactone related compound A, Standard solution

Signal-to-noise ratio: NLT 10, Sensitivity solution Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of benzothiadiazine related compound A in the portion of Tablets taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of benzothiadiazine related compound A from the Sample solution

r_S = peak response of benzothiadiazine related compound A from the Standard solution

C_S = concentration of USP Benzothiadiazine Related Compound A RS in the Standard solution (µg/mL)

C_U = nominal concentration of hydrochlorothiazide in the Sample solution (µg/mL)

Calculate the percentage of spironolactone related compound A in the portion of Tablets taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of spironolactone related compound A from the Sample solution

r_S = peak response of spironolactone related compound A from the Standard solution

C_S = concentration of USP Spironolactone Related Compound A RS in the Standard solution (µg/mL)

C_U = nominal concentration of spironolactone in the Sample solution (µg/mL)

Calculate the percentage of any unspecified degradation product in the portion of Tablets taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of any unspecified degradation product from the Sample solution

r_S = peak response of hydrochlorothiazide from the Standard solution

C_S = concentration of USP Hydrochlorothiazide RS in the Standard solution (µg/mL)

C_U = nominal concentration of hydrochlorothiazide in the Sample solution (µg/mL)

Acceptance criteria: See Table 5. The reporting threshold is 0.1%.

Table 5

^a  Excluding benzothiadiazine related compound A.

(USP 1-Dec-2023)

6 ADDITIONAL REQUIREMENTS

Change to read:

PACKAGING AND STORAGE: Preserve in tight, light-resistant containers. Store at controlled room temperature. (USP 1-Dec-2023)

Change to read:

USP REFERENCE STANDARDS 〈11〉

USP Benzothiadiazine Related Compound A RS

4-Amino-6-chloro-1,3-benzenedisulfonamide.

C₆H₈ClN₃O₄S₂       285.73 (USP 1-Dec-2023)

USP Hydrochlorothiazide RS

USP Spironolactone RS

USP Spironolactone Related  Compound A RS

(2’R)-3’,4’-Dihydro-5’H-spiro[androst-4,6-diene-17,2’-furan]-3,5’-dione.

C₂₂H₂₈O₃             340.46 (USP 1-Dec-2023)