Losartan Potassium

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

Losartan Potassium contains NLT 98.5% and NMT 101.0% of losartan potassium (C₂₂H₂₂ClKN₆O), calculated on the anhydrous, solvent-free basis.

2 IDENTIFICATION

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197M or 197K

Meets the requirements

Change to read:

B. The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay. (USP 1-Aug-2021)

C. Identification Tests—General 〈191〉, Chemical Identification Tests, Potassium: Meets the requirements

3 ASSAY

Change to read:

Procedure

Solution A: 0.1% phosphoric acid in water

Solution B: Acetonitrile

Mobile phase: Solution B and Solution A (40:60)

Diluent: Methanol and water (40:60) (USP 1-Aug-2021)

Standard solution: 0.25 mg/mL of USP Losartan Potassium RS in Diluent (USP 1-Aug-2021)

Sample solution: 0.25 mg/mL of Losartan Potassium in Diluent (USP 1-Aug-2021)

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 254 nm

Column: 4.0-mm × 25-cm; 5-μm (USP 1-Aug-2021) packing L1

Column temperature: 35°

Flow rate: 1 mL/min

Injection volume: 10 μL

Run time: NLT 3 times the retention time of losartan (USP 1-Aug-2021)

System suitability

Sample: Standard solution

Suitability requirements

(USP 1-Aug-2021)

Tailing factor: NMT 1.4

Relative standard deviation: NMT 0.5%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of losartan potassium (C₂₂H₂₂ClKN₆O) in the portion of Losartan Potassium taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of losartan (USP 1-Aug-2021) from the Sample solution

r_S = peak response of losartan (USP 1-Aug-2021) from the Standard solution

C_S = concentration of USP Losartan Potassium RS in the Standard solution (mg/mL)

C_U = concentration of Losartan Potassium in (USP 1-Aug-2021) the Sample solution (mg/mL)

Acceptance criteria: 98.5%–101.0% on the anhydrous, solvent-free basis

4 IMPURITIES

Change to read:

Organic Impurities

Solution A and Solution B: Prepare as directed in the Assay. (USP 1-Aug-2021)

Mobile phase: See Table 1.

Table 1

System suitability solution: 0.3 mg/mL of USP Losartan Potassium RS and 2 μg/mL of triphenylmethanol in methanol

Standard solution: 0.3 μg/mL of USP Losartan Potassium RS in methanol

Sensitivity solution: 0.15 μg/mL of USP Losartan Potassium RS in methanol from the Standard solution▲ (USP 1-Aug-2021)

Sample solution: 0.3 mg/mL of Losartan Potassium in methanol

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 220 nm

Column: 4.0-mm × 25-cm; 5-μm (USP 1-Aug-2021) packing L1

Flow rate: 1 mL/min

Injection volume: 10 μL

System suitability

Samples: System suitability solution, Standard solution, and Sensitivity solution (USP 1-Aug-2021)

[Note—The relative retention times for losartan and triphenylmethanol are 1.0 and 1.9, respectively.

(USP 1-Aug-2021) ]

Suitability requirements

Tailing factor: NMT 1.6, System suitability solution

Relative standard deviation: NMT 5.0%, Standard solution

Signal-to-noise ratio: NLT 10, Sensitivity solution (USP 1-Aug-2021)

Analysis

Sample: Sample solution

Calculate the percentage of each impurity in the portion of Losartan Potassium (C₂₂H₂₂ClKN₆O) taken:

Result = (r_U/r_T) × 100

r_U = peak response for each impurity

r_T = sum of the responses for all peaks

Acceptance criteria: The reporting threshold is 0.05%. (USP 1-Aug-2021)

Individual impurities: NMT 0.2%

Total impurities: NMT 0.5%

5 SPECIFIC TESTS

Water Determination 〈921〉, Method I: NMT 0.5%. If labeled as an amorphous form, NMT 5.0%.

6 ADDITIONAL REQUIREMENTS

Labeling: Where it is an amorphous form, the label so indicates.

Packaging and Storage: Preserve in well-closed containers. Store at controlled room temperature.

USP Reference Standards 〈11〉

USP Losartan Potassium RS