Drug Groups

approved

Description

A cardiotonic glycoside obtained mainly from Digitalis lanata; it consists of three sugars and the aglycone digoxigenin. Digoxin has positive inotropic and negative chronotropic activity. It is used to control ventricular rate in atrial fibrillation and in the management of congestive heart failure with atrial fibrillation. Its use in congestive heart failure and sinus rhythm is less certain. The margin between toxic and therapeutic doses is small. (From Martindale, The Extra Pharmacopoeia, 30th ed, p666)

Indication

For the treatment and management of congestive cardiac insufficiency, arrhythmias and heart failure.

Pharmacology

Digoxin, a cardiac glycoside similar to digitoxin, is used to treat congestive heart failure and supraventricular arrhythmias due to reentry mechanisms, and to control ventricular rate in the treatment of chronic atrial fibrillation.

Toxicity

Toxicity includes ventricular tachycardia or ventricular fibrillation, or progressive bradyarrhythmias, or heart block. LD₅₀ = 7.8 mg/kg (orally in mice).

Affected Organisms

Biotransformation

Hepatic (but not dependent upon the cytochrome P-450 system). The end metabolites, which include 3 b-digoxigenin, 3-keto-digoxigenin, and their glucuronide and sulfate conjugates, are polar in nature and are postulated to be formed via hydrolysis, oxidation, and conjugation.

Absorption

Absorption of digoxin from the elixir pediatric formulation has been demonstrated to be 70% to 85% complete (90% to 100% from the capsules, and 60% to 80% for tablets).

Half Life

3.5 to 5 days

Protein Binding

25%

Elimination

Following intravenous administration to healthy volunteers, 50% to 70% of a digoxin dose is excreted unchanged in the urine.

References

External Links