Digoxin

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

DOWNLOAD PDF HERE

1 DEFINITION 

Digoxin is a cardiotonic glycoside obtained from the leaves of Digitalis lanata Ehrh. (Fam. Plantaginaceae, formerly Scrophulariaceae). It contains NLT 95.0% and NMT 101.0% of digoxin (C₄₁H₆₄O₁₄), calculated on the dried basis. [Caution—Handle Digoxin with exceptional care, because it is extremely poisonous.] 

2 IDENTIFICATION 

Change to read: 

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

3.1 Procedure 

Mobile phase: Acetonitrile and water (13:37) 

System suitability solution: 40 µg/mL each of USP Digoxin RS and digoxigenin in diluted alcohol 

Standard solution: 0.25 mg/mL of USP Digoxin RS in diluted alcohol. [Note—Use a sonic bath to aid dissolution.] Sample solution: 0.25 mg/mL of Digoxin in diluted alcohol. [Note—Dissolve using sonication, before make-up to nal volume.] Chromatographic system 

(See Chromatography 〈621〉, System Suitability.) 

Mode: LC 

Detector: UV 218 nm 

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

Column temperature: 25° 

Flow rate: 2 mL/min 

Injection volume: 10 µL 

System suitability 

Sample: System suitability solution 

Suitability requirements 

Resolution: NLT 4.0 between digoxin and digoxigenin 

Column eciency: NLT 1200 theoretical plates for the digoxin peak 

Tailing factor: NMT 2.0 for the digoxin peak 

Relative standard deviation: NMT 2.0% 

Analysis 

Samples: Standard solution and Sample solution 

Calculate the percentage of digoxin (C₄₁H₆₄O₁₄) in the portion of Digoxin taken: 

Result = (r_u/r_s) × (C_s/C_u) × 100

r_u = peak response of digoxin from the Sample solution 

r_s = peak response of digoxin from the Standard solution 

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

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

Acceptance criteria: 95.0%–101.0% on the dried basis 

4 IMPURITIES 

4.1 Residue on Ignition 〈281〉:

NMT 0.5%, a 100-mg specimen being used 

4.2 Related Glycosides 

Solution A: Acetonitrile and water (10:90) 

Solution B: Water and acetonitrile (10:90) 

Mobile phase: See Table 1. 

Table 1 

Standard stock solution: 0.5 mg/mL of USP Digoxin RS and USP Digitoxin RS in methanol 

Standard solution: Dilute 1.0 mL of Standard stock solution with methanol to 100 mL. 

System suitability solution: Dissolve 50 mg of lanatoside C in methanol, and dilute with methanol to 100 mL. To 1.0 mL of this solution add 1.0 mL of Standard stock solution, and dilute with methanol to 20 mL. 

Sample solution: Accurately weigh 25 mg of Digoxin, transfer into a 50-mL volumetric ask, and dilute with methanol to volume. Chromatographic system 

(See Chromatography 〈621〉, System Suitability.) 

Mode: LC 

Detector: UV 220 nm 

Column: 3.9-mm × 15-cm; 5-µm packing L1 

Column temperature: 25° 

Flow rate: 1.5 mL/min 

Injection volume: 10 µL 

System suitability 

Samples: System suitability solution and Standard solution 

Suitability requirements 

Resolution: NLT 1.5 between the digoxin and lanatoside C peaks, System suitability solution 

Relative standard deviation: NMT 2.0%, determined from the digoxin peak in replicated injections, Standard solution Analysis 

Samples: Standard solution and Sample solution 

Calculate the percentages of the peak areas of the total impurities, gitoxin, and digitoxin, against the digoxin peak from the Standard solution. 

Acceptance criteria: See Table 2. 

Table 2 

4.3 Residual Solvents 〈467〉:

2000 µg/g for methylene chloride and for chloroform 

5 SPECIFIC TESTS 

5.1 Loss on Drying 〈731〉 

Analysis: Dry under vacuum at 105° for 1 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 Digoxin RS 

USP Digitoxin RS