Urea C 13 for Oral Solution

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

Urea C 13 for Oral Solution is a dry powder prepared from Urea C 13. It contains NLT 90.0% and NMT 110.0% of the labeled amount of urea C 13 (¹³CH₄N₂O). It contains no preservatives.

2 IDENTIFICATION

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

3 ASSAY

PROCEDURE

Mobile phase: Acetonitrile, methanol, and water (89:10:1)

System suitability solution: 2.5 mg/mL of urea and 0.003 mg/mL of biuret in Mobile phase

Standard solution: 2 mg/mL of USP Urea C 13 RS in Mobile phase

Sample solution: 2 mg/mL of urea C 13 from a portion of Urea C 13 for Oral Solution in Mobile phase

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 200 nm

Column: 4.6-mm x 25-cm; 5-µm packing L8

Flow rate: 0.8 mL/min

Injection volume: 20 µL

System suitability

Samples: System suitability solution and Standard solution

Suitability requirements

Resolution: NLT 1.5 between urea and biuret, System suitability solution

Relative standard deviation: NMT 1%, Standard solution

Analysis

Samples: Standard solution and Sample solution

Measure the areas for the major peaks.

Calculate the percentage of the labeled amount of urea C 13 (¹³CH₄N₂O) in the portion of Urea C 13 for Oral Solution taken:

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

r_u = peak response from the Sample solution

r_s = peak response from the Standard solution

C_s = concentration of USP Urea C 13 RS in the Standard solution (mg/mL)

C_u = nominal concentration of urea C 13 in the Sample solution (mg/mL)

Acceptance criteria: 90.0%–110.0%

4 PERFORMANCE TESTS

Uniformity of Dosage Units 〈905〉: Meets the requirements

SPECIFIC TESTS

Microbial Enumeration Tests 〈61〉andTests for Specified Microorganisms 〈62〉

Acceptance criteria

Total aerobic microbial count: NMT 10³ cfu/g

Yeast count: NMT 10² cfu/g

Salmonella species andEscherichia coli: Absent

Completeness of Solution 〈641〉

Sample solution: Nominally 100 mg/mL of urea C 13 from a portion of Urea C 13 for Oral Solution in carbon dioxide-free water

Acceptance criteria: Meets the requirements

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in sterile, well-closed containers. Store at 15°–30°.

Labeling: Label it to indicate that the solution is to be discarded if particulate matter is visible after reconstitution. [Note—It is to be

reconstituted with sterile puried water.]

USP Reference Standards 〈11〉

USP Urea C 13 RS