Digitalis (Cardiac Glycosides)

General Introduction

• Digitalis is a primary source of potent cardiac glycosides (e.g., digoxin and digitoxin), used to treat heart failure and arrhythmias.

• These compounds are derived from the dried leaves of Digitalis purpurea and Digitalis lanata.

Illustration of Digitalis (Cardiac Glycosides)

Synonyms of Digitalis

• Common Name: Foxglove

• Scientific Names: Digitalis purpurea, Digitalis lanata

• Other: Foxglove glycosides

Biological Source & Family

• Source: Dried leaves

• Family: Plantaginaceae

Composition

• Cardiac Glycosides:

  • Primary: Purpurea glycosides A and B, Lanatosides A, B, and C

  • Active Forms: Digoxin, Digitoxin

• Other Compounds: Flavonoids (e.g., luteolin) and sterols (cholesterol, sitosterols)

Chemistry

• Class: Cardiac glycosides

• Structure: Steroid nucleus with a lactone ring at C-17 and sugar residues at C-3. The unsaturated (α,β-unsaturated) lactone ring is key for activity.

• Solubility: Mainly lipophilic; glycosylation enhances water solubility.

Therapeutic Uses & Commercial Applications

• Cardiotonic Effects: Increases cardiac contraction (positive inotropy) and slows heart rate (negative chronotropy), benefiting patients with congestive heart failure and atrial fibrillation.

• Antiarrhythmic: Particularly effective for atrial flutter/fibrillation management.

• Market Forms: Available as oral and injectable formulations (e.g., Lanoxin for digoxin).