Thiamine Mononitrate 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

Thiamine Mononitrate Oral Solution contains NLT 95.0% and NMT 115.0% of the labeled amount of thiamine mononitrate (C₁₂H₁₇N₅O₄S).

2 IDENTIFICATION

A.

Sample solution: Dilute a portion of Oral Solution with water to a concentration of 10 mg/mL of thiamine mononitrate.

Analysis: To 0.5 mL of the Sample solution add 5 mL of 0.5 N sodium hydroxide, then add 0.5 mL of potassium ferricyanide TS and 5 mL of isobutyl alcohol. Shake the mixture vigorously for 2 min, and allow the liquid layers to separate. Illuminate from above by a vertical beam of UV light and observe the air–liquid meniscus at a right angle to this beam.

Acceptance criteria: The air–liquid meniscus shows a vivid blue fluorescence, which disappears when the mixture is slightly acidified, but reappears when it is again made alkaline.

B.

Sample: 5 mL of Oral Solution

Analysis: Add 2 mL of sulfuric acid to the Sample, cool, and superimpose 2 mL of ferrous sulfate TS.

Acceptance criteria: A brown ring is produced at the junction of the two liquids.

3 ASSAY

Procedure

Mobile phase: Methanol and 0.04 M aqueous monobasic potassium phosphate (45:55)

Internal standard solution: 100 μg/mL of methylparaben in Mobile phase

Standard stock solution: 500 μg/mL of USP Thiamine Hydrochloride RS in Mobile phase

Standard solution: Dilute a mixture of equal volumes of the Standard stock solution and Internal standard solution with Mobile phase to obtain a concentration of USP Thiamine Hydrochloride RS of 50 μg/mL.

Sample stock solution: Equivalent to 500 μg/mL of thiamine mononitrate in Mobile phase from an accurately measured volume of Oral

Solution

Sample solution: Dilute a mixture of equal volumes of the Sample stock solution and Internal standard solution with Mobile phase to obtain a concentration of thiamine mononitrate of 50 μg/mL.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 254 nm

Column: 3.9-mm × 30-cm; packing L1

Flow rate: 1 mL/min

Injection size: 25 μL

System suitability

Sample: Standard solution

[Note—The relative retention times for thiamine and methylparaben are about 0.35 and 1.0, respectively.]

Suitability requirements

Resolution: NLT 6.0 between the thiamine and methylparaben

Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of thiamine mononitrate in the portion of Oral Solution taken:

Result = (R_U/R_S) × (C_S/C_U) × (M_r1/M_r2) × 100

R_U = peak area ratio of thiamine to methylparaben from the Sample solution

R_S = peak area ratio of thiamine to methylparaben from the Standard solution

C_S = concentration of USP Thiamine Hydrochloride RS in the Standard stock solution (μg/mL)

C_U = nominal concentration of thiamine mononitrate in the Sample stock solution (μg/mL)

M_r1 = molecular weight of thiamine mononitrate, 327.36

M_r2 = molecular weight of thiamine hydrochloride, 337.27

Acceptance criteria: 95.0%–115.0%

4 OTHER COMPONENTS

Alcohol Determination, Method II 〈611〉: 90.0%–110.0% of the labeled quantity of C H OH, using acetone as the internal standard

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight, light-resistant containers.

USP Reference Standards 〈11〉

USP Thiamine Hydrochloride RS