Secobarbital Sodium Capsules

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

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

DOWNLOAD PDF HERE

1 DEFINITION 

Secobarbital Sodium Capsules contain NLT 92.5% and NMT 107.5% of the labeled amount of secobarbital sodium (C₁₂H₁₇N₂NaO₃). 

2 IDENTIFICATION 

Change to read: 

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy (CN 1-May-2020)

Sample solution: Nominally 5 mg/mL of secobarbital sodium in water from the contents of Capsules 

Analysis: Transfer 10 mL of the filtered Sample solution to a separator. Add 2 mL of 3 N hydrochloric acid. Extract the liberated secobarbital with 20 mL of chloroform, and evaporate the extract to dryness. Dissolve the residue in chloroform to prepare a 5-mg/mL solution. Acceptance criteria: The Sample solution exhibits maxima only at the same wavelengths as that of a similar preparation of USP Secobarbital 

B. The retention time of the secobarbital peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay. 

3 ASSAY 

Procedure 

Solution A: Phosphoric acid and water (80:20) 

Buffer: 1.4 g/L of monobasic potassium phosphate in water adjusted with Solution A to a pH of 3.5 

Mobile phase: Acetonitrile and Buffer (35:65) 

Diluent: Acetonitrile and water (35:65) 

Standard solution: 0.4 mg/mL of USP Secobarbital RS in Diluent. Sonication may be used to aid in dissolution. Sample solution: Nominally 0.4 mg/mL of secobarbital sodium in a solution prepared as follows. Transfer the equivalent of 44 mg of secobarbital sodium from the contents of NLT 20 Capsules to a 100-mL volumetric flask. Dilute with Diluent to volume. Shaking and sonication may be used to aid in dissolution. Centrifuge a portion of this solution, and use the supernatant. Chromatographic system 

(see Chromatography 〈621〉, System Suitability) 

Mode: LC 

Detector: 215 nm 

Column: 4.6-mm × 15.0-cm; 3.5-µm packing L1 

Flow rate: 1 mL/min 

Injection volume: 10 µL 

Run time: 2 times the retention time of secobarbital 

System suitability 

Sample: Standard solution 

Suitability requirements 

Tailing factor: NMT 1.5 

Relative standard deviation: NMT 1.0% 

Analysis 

Samples: Standard solution and Sample solution 

Calculate the percentage of the labeled amount of secobarbital sodium (C₁₂H₁₇N₂NaO₃) in the portion of Capsules taken: 

Result = (r_U/r_S ) × (C /C_U) × (M_r1/M_r2) × 100 

r_U = peak response from the Sample solution 

r_S = peak response from the Standard solution 

C_S = concentration of USP Secobarbital RS in the Standard solution (mg/mL) 

C_U = nominal concentration of secobarbital sodium in the Sample solution (mg/mL) 

M_r1 = molecular weight of secobarbital sodium, 260.26 

M_r2 = molecular weight of secobarbital, 238.28 

Acceptance criteria: 92.5%–107.5% 

4 PERFORMANCE TESTS 

Dissolution 〈711〉 

Medium: Water; 500 mL 

Apparatus 1: 100 rpm 

Time: 60 min 

Standard solution: USP Secobarbital RS in 0.1 N sodium hydroxide 

Sample solution: Solution under test, mixed with sufficient sodium hydroxide to provide a concentration of 0.1 N sodium hydroxide, and diluted with Medium, as needed, so that the concentration is similar to that of the Standard solution 

Instrumental conditions 

Mode: UV 

Analytical wavelength: 243 nm 

Tolerances: NLT 75% (Q) of the labeled amount of secobarbital sodium (C₁₂H₁₇N₂NaO₃) is dissolved. 

Uniformity of Dosage Units 〈905〉: Meet the requirements 

5 IMPURITIES

Organic Impurities 

Solution A, Buffer, Mobile phase, Diluent, and Chromatographic system: Proceed as directed in the Assay. Standard solution: 0.005 mg/mL of USP Secobarbital RS in Diluent. Sonication may be used to aid in dissolution. Sample solution: Nominally 1 mg/mL of secobarbital sodium in a solution prepared as follows. Transfer the equivalent of 100 mg of secobarbital sodium from NLT 20 Capsules to a 100-mL volumetric flask. Dilute with Mobile phase to 50% of the nal flask volume. Sonicate and shake. Dilute with Mobile phase to volume. Pass through a suitable lter of 0.45-µm pore size. 

System suitability 

Sample: Standard solution 

Suitability requirements 

Tailing factor: NMT 1.5 

Relative standard deviation: NMT 6.0% 

Analysis 

Samples: Standard solution and Sample solution 

Calculate the percentage of any individual unspecified degradant in the portion of Capsules taken: 

Result = (r_U/r_S ) × (C /C_U) × (M_r1/M_r2) × 100 

r_U = peak response of any individual unspecified degradant from the Sample solution 

r_S = peak response from the Standard solution 

C_S = concentration of USP Secobarbital RS in the Standard solution (mg/mL) 

C_U = nominal concentration of secobarbital sodium in the Sample solution (mg/mL) 

M_r1 = molecular weight of secobarbital sodium, 260.26 

M_r2 = molecular weight of secobarbital, 238.28 

Acceptance criteria: See Table 1. 

Table 1 

a 5-Allyl-4-imino-5-(1-methylbutyl) barbituric acid.

b 5-(2-Hydroxypropyl)-5-(1-methylbutyl) barbituric acid. 

c 5-Allyl-5-(1-3-dimethylbutyl) barbituric acid. 

6 ADDITIONAL REQUIREMENTS 

Packaging and Storage: Preserve in tight containers. 

USP Reference Standards 〈11〉 

USP Secobarbital RS