Butabarbital 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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C₁₀H₁₅N₂NaO₃  234.23

2,4,6(1H,3H,5H)-Pyrimidinetrione, 5-ethyl-5-(1-methylpropyl)-, monosodium salt; Sodium 5-sec-butyl-5-ethylbarbiturate CAS RN^®: 143-81-7; UNII: 9WTD501918.

1 DEFINITION

Butabarbital Sodium contains NLT 98.2% and NMT 100.5% of butabarbital sodium (C₁₀H₁₅N₂NaO₃), calculated on the dried basis.

2 IDENTIFICATION

Change to read:

2.1 A. ASPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 197K (CN 1-MAY-2020)

Sample: 150 mg of Butabarbital Sodium

Analysis: Transfer the Sample to a suitable separator, dissolve in 10 mL of water, and add 15 mL of 3 N hydrochloric acid. Extract with three 20-mL portions of chloroform, filter the extracts through anhydrous sodium sulfate, and collect the extracts in a suitable beaker. Evaporate the combined extracts on a steam bath with the aid of a current of air to dryness, and dry the residue at 105° for 2 h.

Acceptance criteria: Meets the requirements

Change to read:

2.2 B. ASPECTROSCOPIC IDENTIFICATION TESTS (197), Ultraviolet-Visible Spectroscopy: 1970 (CN 1-MAY-2020)

Analytical wavelength: 240 nm

Buffer: pH 9.6 alkaline borate buffer (see Reagents, Indicators, and Solutions-Buffer Solutions)

Standard solution: 10 µg/mL of USP Butabarbital RS in Buffer

Sample solution: 10 µg/mL of Butabarbital Sodium in Buffer

Acceptance criteria: Absorptivities, calculated on the dried basis, do not differ by more than 3.0%.

2.3 C. IDENTIFICATION TESTS GENERAL, Sodium (191)

Sample: 100 mg of Butabarbital Sodium

Analysis: Ignite the Sample, and proceed as directed in the chapter using the residue.

Acceptance criteria: Meets the requirements

3 ASSAY

3.1 PROCEDURE

Buffer: pH 9.6 alkaline borate buffer (see Reagents, Indicators, and Solutions-Buffer Solutions)

Standard stock solution: 0.125 mg/mL of USP Butabarbital RS in Buffer

Standard solution: 0.0125 mg/mL of USP Butabarbital RS from Standard stock solution in Buffer

Sample stock solution: 0.140 mg/mL of Butabarbital Sodium in Buffer

Sample solution: 0.0140 mg/mL from Sample stock solution in Buffer

Instrumental conditions

Mode: UV

Analytical wavelength: Maximum absorbance at about 240 nm

Blank: Buffer

Analysis

Samples: Standard solution, Sample solution, and Blank

Concomitantly determine the absorbances of the solutions.

Calculate the percentage of butabarbital sodium (C₁₀H₁₅N₂NaO₃) in the portion of Butabarbital Sodium taken:

Result = (A_U/A_S) × (C_S/C_U) × (M_r1/M_r2) × 100

A_U = absorbance of the Sample solution

A_S = absorbance of the Standard solution

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

C_U = concentration of Butabarbital Sodium in the Sample solution (µg/mL)

M_r1 = molecular weight of butabarbital sodium, 234.23

M_r2 = molecular weight of butabarbital, 212.25

Acceptance criteria: 98.2%-100.5% on the dried basis

4 IMPURITIES

4.1 ORGANIC IMPURITIES

Diluent: Chloroform and methanol (50:50)

Standard solution A: 4.0 mg/mL of USP Butabarbital RS in Diluent

Standard solution B: 0.4 mg/mL of USP Butabarbital RS from Standard solution A in Diluent

Sample solution: 44 mg/mL of Butabarbital Sodium in Diluent

Chromatographic system

(See Chromatography (621), Thin-Layer Chromatography.)

Mode: TLC

Adsorbent: 0.25-mm layer of chromatographic silica gel mixture

Application volume: 10 µL

Developing solvent system: Acetone, methylene chloride, methanol, and ammonium hydroxide (5:3:1:1)

Spray reagent: A solution of mercurous nitrate dihydrate in 0.15 N nitric acid (1 in 100)

Analysis

Samples: Standard solution A, Standard solution B, and Sample solution

Develop the chromatogram in the Developing solvent system until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, and dry under a current of air. Spray the plate with Spray reagent, and immediately estimate the intensities of any spots of the Sample solution, other than the principal spot, in comparison with Standard solution B.

Acceptance criteria: The Re value of the principal spot of the Sample solution corresponds to that of Standard solution A; and the sum of the intensities of any secondary spots of the Sample solution is NMT the intensity of the principal spot produced by Standard solution B, corresponding to NMT a total of 1% of impurities.

5 SPECIFIC TESTS

5.1 COMPLETENESS OF SOLUTION

Sample solution: Dissolve 1.0 g of Butabarbital Sodium in 10 mL of carbon dioxide-free water.

Acceptance criteria: After 1 min, the solution is clear and free from undissolved solid.

5.2 PH (791)

Sample solution: Use the Sample solution from the test for Completeness of Solution.

Acceptance criteria: 10.0-11.2

5.3 LOSS ON DRYING (731)

Analysis: Dry at 150° to constant weight.

Acceptance criteria: NMT 5.0%

6 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in tight containers.

USP REFERENCE STANDARDS (11).

USP Butabarbital RS