Aminobenzoate Potassium Capsules

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

Aminobenzoate Potassium Capsules contain NLT 90.0% and NMT 110.0% of the labeled amount of aminobenzoate potassium (C₇H₆KNO₂).

2 IDENTIFICATION

A.

Sample: 1 g of the Capsule contents

Analysis: Dissolve the Sample in 25 mL of water, add 5 mL of 3 N hydrochloric acid, and wash the precipitate with two 5-mL portions of cold water. Recrystallize from alcohol the precipitate so obtained, and dry at 110° for 1 h.

Acceptance criteria: The p-aminobenzoic acid melts between 186° and 189°.

B. 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

3.1 Procedure

Solution A: 1.5% acetic acid prepared as follows. Mix 690 mL of water with 10 mL of acetic acid and pass through a filter of 0.45-μm pore size.

Mobile phase: Methanol and Solution A (15:85)

Standard solution: 0.1 mg/mL of USP Aminobenzoate Potassium RS in Mobile phase

Sample solution: Nominally 0.1 mg/mL of aminobenzoate potassium prepared as follows. Remove as completely as possible, and combine the contents of NLT 10 Capsules. Transfer a portion of the combined contents, equivalent to 10 mg of aminobenzoate potassium to a 100mL volumetric flask, dissolve in 70 mL of Mobile phase, sonicate for 3–4 min, and dilute with Mobile phase to volume.

3.2 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: 280 nm

Column: 3.0-mm × 15-cm; 3.5-μm packing L11

Flow rate: 0.35 mL/min

Injection volume: 5 μL

3.3 System suitability

Sample: Standard solution

3.4 Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0%

3.5 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of aminobenzoate potassium (C₇H₆KNO₂) in the portion of Capsules 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 Aminobenzoate Potassium RS in the Standard solution (mg/mL)

C_u = nominal concentration of aminobenzoate potassium in the Sample solution (mg/mL)

Acceptance criteria: 90.0%–110%

4 PERFORMANCE TESTS

Dissolution 〈711〉

Medium: Water; 900 mL

Apparatus 1: 100 rpm

Time: 45 min

Instrumental conditions

Mode: UV

Analytical wavelength: Maximum absorbance at about 270 nm

Standard solution: A known concentration of USP Aminobenzoate Potassium RS in Medium

Sample solution: Filter portions of the solution under test, and dilute with Medium, if necessary, in comparison with the Standard solution concentration.

Analysis: Calculate the percentage of the labeled amount of aminobenzoate potassium (C₇H₆KNO₂) dissolved.

Tolerances: NLT 75% (Q) of the labeled amount of aminobenzoate potassium (C₇H₆KNO₂) is dissolved.

Uniformity of Dosage Units 〈905〉: Meet the requirements

5 IMPURITIES

5.1 Organic Impurities

Solution A, Mobile phase, and Chromatographic system: Prepare as directed in the Assay.

Standard solution: 1 μg/mL each of USP Aminobenzoate Potassium RS, USP 4-Nitrobenzoic Acid RS, and USP Benzocaine RS in Mobile phase

Sensitivity solution: 0.1 μg/mL of USP Aminobenzoate Potassium RS in Mobile phase from the Standard solution

Sample solution: Nominally 1 mg/mL of aminobenzoate potassium in Mobile phase prepared as follows. Remove as completely as possible, and combine, the contents of NLT 10 Capsules. Transfer a portion of the combined contents, equivalent to 10 mg of aminobenzoate potassium, to a 10-mL volumetric flask. Dissolve in 7 mL of Mobile phase, sonicate for 3–4 min, and dilute with Mobile phase to volume.

5.2 System suitability

Samples: Standard solution and Sensitivity solution

5.3 Suitability requirements

Resolution: NLT 1.5 between benzocaine and 4-nitrobenzoic acid, Standard solution

Tailing factor: NMT 2.0, Standard solution

Relative standard deviation: NMT 5.0%, Standard solution

Signal-to-noise ratio: NLT 10, Sensitivity solution

5.4 Analysis

Samples: Standard solution and Sample solution

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

Result = (r_u/r_s) × (C_s/C_u)× 100

r_u = peak response of any individual unspecified degradation product from the Sample solution

r_s = peak response of aminobenzoate from the Standard solution

C_s = concentration of USP Aminobenzoate Potassium RS in the Standard solution (mg/mL)

C_u = nominal concentration of aminobenzoate potassium in the Sample solution (mg/mL)

Acceptance criteria: See Table 1.

Table 1

^a These are process impurities controlled in the API and are included in this table for identification purposes only. They are not reported in the drug product and should not be included in the total impurities.

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers.

USP Reference Standards 〈11〉

USP Aminobenzoate Potassium RS

USP Benzocaine RS

USP 4-Nitrobenzoic Acid RS

4-Nitrobenzoic acid.

C₇H₅NO₄  167.12