Phenazopyridine Hydrochloride

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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C₁₁H₁₁N₅·HCI 249.70

2,6-Pyridinediamine, 3-(phenylazo)-, monohydrochloride;

2,6-Diamino-3-(phenylazo)pyridine monohydrochloride CAS RN^®: 136-40-3; UNII: 0EWG668W17.

1 DEFINITION

Phenazopyridine Hydrochloride contains NLT 98.0% and NMT 102.0% of phenazopyridine hydrochloride (C₁₁H₁₁N₅·HCI), calculated on the dried basis.

2 IDENTIFICATION

Change to read:

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

Change to read:

Medium: Sulfuric acid in alcohol (1 in 360)

Sample solution: 5 µg/mL of Phenazopyridine Hydrochloride in Medium

Acceptance criteria: Meets the requirements

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

D. Identification Tests-General, Chemical Identification Tests, Chloride〈191〉: Meets the requirements

3 ASSAY

3.1 PROCEDURE

Solution B: Acetonitrile

Mobile phase: See Table 1.

Table 1

Diluent: Acetonitrile and water (10:90)

Standard solution: 0.03 mg/mL of USP Phenazopyridine Hydrochloride RS in Diluent

Sample solution: 0.03 mg/mL of Phenazopyridine Hydrochloride in Diluent

3.2 Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 280 nm

Column: 4.6-mm x 25-cm; 5-µm packing L1

Flow rate: 1 mL/min

Injection volume: 20 µL

3.3 System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 0.73%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of phenazopyridine hydrochloride (C₁₁H₁₁N₅·HCI) in the portion of Phenazopyridine Hydrochloride taken:

Result = (r_U/r_S) x (C_S/C_U) x 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

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

C_U = concentration of Phenazopyridine Hydrochloride in the Sample solution (mg/mL)

Acceptance criteria: 98.0%-102.0 % on the dried basis

4 IMPURITIES

4.1 RESIDUE ON IGNITION (281)

NMT 0.2%

4.2 WATER-INSOLUBLE SUBSTANCES

Sample: 2 g of Phenazopyridine Hydrochloride

Analysis: Dissolve the Sample in 200 mL of water, heat to boiling, and then heat in a covered container on a steam bath for 1 h. Filter through a tared, fine-porosity, sintered-glass crucible, wash thoroughly with water, and dry at 105° to constant weight.

Acceptance criteria: The weight of the residue does not exceed 0.1% of the weight of Phenazopyridine Hydrochloride taken.

4.3 ORGANIC IMPURITIES

Solution A, Solution B, Mobile phase, and Diluent: Proceed as directed in the Assay.

Sensitivity solution: 0.25 µg/mL each of USP Phenazopyridine Hydrochloride RS and 2,6-diaminopyridine in Diluent

Standard solution: 0.0005 mg/mL of USP Phenazopyridine Hydrochloride RS and 0.001 mg/mL of 2,6-diaminopyridine in Diluent

Sample solution: 0.5 mg/mL of Phenazopyridine Hydrochloride in Diluent

Chromatographic system: Proceed as directed in the Assay except for the Detector.

Detector: UV 240 nm

System suitability

Samples: Sensitivity solution and Standard solution

Suitability requirements

Tailing factor: NMT 1.5 for the phenazopyridine peak, Standard solution

Relative standard deviation: NMT 3.0% for the phenazopyridine peak, Standard solution

Signal-to-noise ratio: NLT 30 for the phenazopyridine peak, Sensitivity solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of 2,6-diaminopyridine in the portion of Phenazopyridine Hydrochloride taken:

Result = (r_U/r_S) x (C_S/C_U) x 100

r_U = peak response of 2,6-diaminopyridine from the Sample solution

r_S = peak response of 2,6-diaminopyridine from the Standard solution

C_S = concentration of 2,6-diaminopyridine in the Standard solution (mg/mL)

C_U = concentration of Phenazopyridine Hydrochloride in the Sample solution (mg/mL)

Calculate the percentage of any individual unspecified impurity in the portion of Phenazopyridine Hydrochloride taken:

Result = (r_U/r_S) x (C_S/C_U) x 100

r_U = peak response of each individual unspecified impurity from the Sample solution

r_S = peak response of phenazopyridine from the Standard solution

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

C_U = concentration of Phenazopyridine Hydrochloride in the Sample solution (mg/mL)

Acceptance criteria: See Table 2. Disregard any impurity peaks less than 0.05%.

Table 2

5 SPECIFIC TESTS

LOSS ON DRYING (731)

Analysis: Dry at 105° for 4 h.

Acceptance criteria: NMT 1.0%

6 ADDITIONAL REQUIREMENTS

6.1 PACKAGING AND STORAGE

Preserve in tight containers.

6.2 USP REFERENCE STANDARDS (11)

USP Phenazopyridine Hydrochloride RS