Docusate Sodium

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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C₂₀H₃₇NaO₇S          444.56

Butanedioic acid, sulfo-, 1,4-bis(2-ethylhexyl) ester, sodium salt, Sodium 1,4-bis(2-ethylhexyl) sulfosuccinate CAS RN: 577-11-7.

1 DEFINITION

Docusate sodium contains NLT 99.0% and NMT 100.5% of C₂H₂, NaO, S, calculated on the anhydrous basis.

2 IDENTIFICATION

PROCEDURE

Sample: Place a small piece of Docusate Sodium on a salt plate, add one drop of acetone, and promptly cover with another salt plate, Rub the plates together to dissolve the specimen, slide the plates apart, and allow the acetone to evaporate.

Acceptance criteria: The IR absorption spectrum of the film exhibits maxima only at the same wavelengths as that of a similar preparation of

USP Docusate Sodium RS.

3 ASSAY

PROCEDURE

Solution A: 2.5 g/L of tetra-n-butylammonium iodide in water

Solution B: A mixture of 100 g/L of anhydrous sodium sulfate and 10 g/L of sodium carbonate in water

Sample: 50 mg

Analysis: Dissolve the Sample in 50 mL of chloroform in a glass-stoppered, 250-mL conical flask. Add 50 mL of Solution B and 500 µL of bromophenol blue TS. Titrate with Solution A until 1 mL from the endpoint, and shake the stoppered flask vigorously for 2 min. Continue the titration in two-drop increments, shaking vigorously for 10 s after each addition, and then allow the flask to stand 10 s. Continue the titration until the chloroform layer just assumes a blue color. Each mL of Solution A is equivalent to 3.009 mg of C₂H₃, NaO,S. 20

Acceptance criteria: 99.0%-100.5% on the anhydrous basis

4 IMPURITIES

4.1 INORGANIC IMPURITIES

RESIDUE ON IGNITION (281): Between 15.5% and 16.5%, calculated on the anhydrous basis

Procedure: Transfer about 1 g, accurately weighed, to a tared crucible, ignite until thoroughly charred, and cool. Moisten the ash with 1 mL of sulfuric acid, and complete the ignition by heating at 800 ± 25° for 15-min periods to constant weight.

4.2 ORGANIC IMPURITIES

PROCEDURE: LIMIT OF BIS(2-ETHYLHEXYL) MALEATE

Mobile phase: Alcohol and water (78:22), filtered and degassed

Standard solution: 80 µg/mL of USP Bis(2-ethylhexyl) Maleate RS in alcohol

Sample solution: 20 mg/mL of Docusate Sodium in alcohol. [NOTE-If necessary, warm the mixture using the steam bath to achieve a complete dissolution.]

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 210 nm

Column: 4.6-mm x 3-cm; 3.5-µm packing L1

Column temperature: 30^o

Flow rate: 1 mL/min

Injection size: 3 µL

System suitability

Sample: Standard solution

Suitability requirements

Relative standard deviation: NMT 2.0% for replicate injections

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of bis(2-ethylhexyl) maleate in the portion of Docusate Sodium taken:

Result = (r_u /r_s ) × (C_s /C_u ) × 100

r_u = peak response of bis(2-ethylhexyl) maleate from the Sample solution

r_s = peak response of bis(2-ethylhexyl) maleate from the Standard solution

C_s = concentration of USP Bis(2-ethylhexyl) Maleate RS in the Standard solution (mg/mL)

C_u = concentration of Docusate Sodium in the Sample solution (mg/mL)

Acceptance criteria: NMT 0.4%

5 SPECIFIC TESTS

Water Determination, Method I 〈921〉: NMT 2.0%

Clarity of Solution

Sample solution: 25 g in 100 mL of alcohol

Acceptance criteria: The Sample solution does not develop a haze within 24 h.

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers.

USP Reference Standards 〈11〉

USP Bis(2-ethylhexyl) Maleate RS C₂₀H₃₆O₄          340.51

USP Docusate Sodium RS