Triamterene

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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C₁₂H₁₁N₇     253.26

2,4,7-Pteridinetriamine, 6-phenyl-;

2,4,7-Triamino-6-phenylpteridine;

6-Phenylpteridine-2,4,7-triamine CAS RN: 396-01-0; UNII: WS821Z52LQ.

1 DEFINITION

Triamterene contains NLT 98.0% and NMT 102.0% of triamterene (C₁₂H₁₁N₇), calculated on the dried basis.

2 IDENTIFICATION

Change to read:

A. SPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 197A or 197M _{(CN 1-May-2020)}

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

PROCEDURE

Mobile phase: Acetonitrile, methanol, butylamine, and water (140:140:2:720). Sonicate to mix and adjust with acetic acid to a pH of 5.3.

Standard solution: 0.05 mg/mL of USP Triamterene RS in Mobile phase

Sample solution: 0.05 mg/mL of Triamterene in Mobile phase

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 355 nm

Column: 4.0-mm x 25-cm; 5-µm packing 17

Flow rate: 1 mL/min

Injection volume: 20 µL

Run time: NLT 3 times the retention time of triamterene

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 triamterene (C₁₂H₁₁N₇) in the portion of Triamterene taken:

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

r_u = peak response of triamterene from the Sample solution

r_s = peak response of triamterene from the Standard solution

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

C_u = concentration of Triamterene in the Sample solution (mg/mL)

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

4 IMPURITIES

ORGANIC IMPURITIES

Mobile phase and Chromatographic system: Proceed as directed in the Assay.

Diluent: To 50 mL of 0.1 N sodium hydroxide in a 500-mL volumetric flask, add 250 mL of acetonitrile and dilute with water to volume.

Standard stock solution 1: 0.25 mg/mL of USP Triamterene RS in Mobile phase

Standard stock solution 2: 0.1 mg/mL of USP Triamterene Related Compound A RS in Diluent. Sonication may be required for complete dissolution.

Standard stock solution 3: 0.1 mg/mL of USP Triamterene Related Compound B RS in Diluent. Sonication may be required for complete dissolution.

Standard stock solution 4: 0.1 mg/mL of USP Triamterene Related Compound C. RS in Diluent. Sonication may be required for complete dissolution.

System suitability solution: 0.1 mg/mL of USP Triamterene RS from Standard stock solution 1 and 0.01 mg/mL of USP Triamterene Related

Compound B RS from Standard stock solution 3 in Mobile phase

Sensitivity solution: 0.5 µg/mL of USP Triamterene RS in Mobile phase from Standard stock solution 1

Standard solution: 0.001 mg/mL each of USP Triamterene RS, USP Triamterene Related Compound A RS, USP Triamterene Related Compound B RS, and USP Triamterene Related Compound C RS from the respective Standard stock solution in Mobile phase

Sample solution: 1 mg/mL of Triamterene in Mobile phase. [NOTE-Sonication may be required to aid the dissolution.]

System suitability

Samples: System suitability solution, Sensitivity solution, and Standard solution

[NOTE-See Table 1 for the relative retention times for triamterene related compound B and triamterene.]

Suitability requirements

Resolution: NLT 2.0 between triamterene related compound B and triamterene, System suitability solution

Relative standard deviation: NMT 5.0%, Standard solution

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

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of triamterene related compound A, triamterene related compound B, and triamterene related compound C in the portion of Triamterene taken:

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

r_u = peak response of each corresponding specied impurity from the Sample solution

r_s = peak response of each corresponding specied impurity from the Standard solution

C_s = concentration of each corresponding specied impurity in the Standard solution (mg/mL)

C_u = concentration of Triamterene in the Sample solution (mg/mL)

Calculate the percentage of any unspecied impurity in the portion of Triamterene taken:

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

r_u = peak response of any unspecied impurity from the Sample solution

r_s = peak response of triamterene from the Standard solution

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

C_u = concentration of Triamterene in the Sample solution (mg/mL)

Acceptance criteria: See Table 1. Reporting threshold: 0.05%.

Table 1

5 SPECIFIC TESTS

Loss on Drying 〈731〉

Analysis: Dry under vacuum at 105° for 2 h.

Acceptance criteria: NMT 1.0%

6 ADDITIONAL REQUIREMENTS

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

USP Reference Standards 〈11〉

USP Triamterene RS

USP Triamterene Related Compound A RS

5-Nitrosopyrimidine-2,4,6-triamine.

C₄H₆N₆O            154.13

USP Triamterene Related Compound B RS

2,7-Diamino-6-phenylpteridin-4-ol.

C₁₂H₁₀N₆O          254.25

USP Triamterene Related Compound C RS

2,4-Diamino-6-phenylpteridin-7-ol.

C₁₂H₁₀N₆O          254.25