Botanical Name: Digitalis purpurea

Common Name: Foxglove

Family:  Scrophulariaceae

 

Foxglove is another great example of a modern drug that not only stemmed (no pun intended) from a plant but is also still made from the actual plant, as the synthetic version is too expensive to manufacture. The drug version, Digoxin (Digox, Digitek, Lanoxin, and Lanoxin Pediatric), is used in cardiovascular patients to treat heart failure and atrial fibrillation.

 

Similar to Veratrum/False Hellebore, this is a very powerful herb with extremely high effects and should not be used except under direct physician care. Even the most experienced herbalist or herb-focused doctors tend to prefer to use the actual drug, as it is standardized and offers a safer prescribing experience. This herb should only be used by the public in diluted doses, such as in Genestra’s HHR Cardio Drops. A much safer and still effective herb would be hawthorne/Crataegus as used in Wise Woman Herbal’s Hawthorne & Linden Tonic.

 

Description of Foxglove Plant/Habitat:

Foxglove is a biennial plant that grows 2-5 feet tall.  The plant flowers from June to September.  The flowers are pink to purple with deeper purple spots inside petals which are fused into a long tube which measures 4-6 cm long, has four stamens, numerous flowers, stalked, somewhat drooping in a long, 1-sided raceme.  Produces numerous egg-shaped capsules with very small seeds.  It grows along roadsides, fields, forest edges and mostly at low elevations.  Foxglove is indigenous to Europe and introduced to the United States.

 

Part(s) used:

Only the leaf is used when preparing foxglove for consumption.

 

Key Active Components:

Cardiac glycosides: digitoxin (extremely poisonous and cumulative), digoxin, digitalin, and digitonin.  The plant foxglove is still is refined commercially as the drug Digoxin (Lanoxin).

 

Foxglove Properties:

  • Digitalis is not commonly used as a medicinal herb due to toxicity of its therapeutic dose. The toxicity of Digitalis has led to the isolation of digoxin which is the least cumulative and most rapidly excreted cardiac glycoside found in Digitalis.
  • The glycosides in Digitalis are the strongest cardiac glycosides known; all other cardiac glycoside containing plants are compared against Digitalis to assess their relative strength.
  • Digoxin exerts strong positive inotropic action on the myocardium (strengthens the force of the heart contraction).
  • In low doses, digoxin exerts a negative chronotropic action (decreases the heart rate), but in increasing dosages, it becomes a positive chronotropic agent (increases the heart rate).

 

Taste/Character/Energetics:

Acrid, bitter

 

Summary of Actions:

Primary Actions:  positive inotropic (strengthens the force of the heart contraction), negative chronotropic (decreases the heart rate), anti-arrhythmic (decreases irregular heartbeats)

 

Medicinal Use:

Overview:

  • Digitalis derives its common name from the shape of the flowers resembling the finger of a glove. Originally, it was called Folksglove—the glove of the ‘good folk’ or fairies who were supposed to live in the woody places where the Foxglove grew.
  • Digitalis is rarely used as a whole plant extract due to potential lethal toxicity and side effects. The therapeutic and toxic dose are very close.
  • Digitalis is the source of digoxin.

Cardiovascular:

  • Primary use is for Congestive Heart Failure (CHF).
  • Strengthens ejection fraction which in turn strengthens strength of systolic beat.
  • Increases length of diastole. This allows the heart to rest between contractions and enhances the effectiveness of the muscle contraction. Mild vasoconstriction of arterioles increases blood pressure.
  • Specific for atrial fibrillation. Fibrillation may be due to malnutrition of the heart muscle and Digitalis will increase blood supply to the heart to help restore nutrition.  It also controls fibrillation by inhibiting conductivity through the AV node.  When palpitations are due to a nervous etiology then Cactus is a better choice.
  • Can reduce edema associated with CHF. It is not a direct diuretic, but does increase urinary flow, probably due to enhanced function of the heart leading to increased blood supply to the kidneys.

 

Specific Indications:

  • Congestive heart failure (CHF)
  • Atrial fibrillation
  • New research is showing that it is also effective for cancer. One recent study stated “It is reasonable to expect that the addition of digitalis to current cancer treatments will improve the clinical outcomes.”

 

Foxglove Safety:

Side Effects/Toxicity:

  • Arrhythmia, nausea, vomiting, abdominal pain, headache, tremors, anxiety, salivation, miosis, giddiness, blurred vision (may see yellow halo around lights), mental disturbance, constriction of renal blood vessels leading to aneuria, convulsions and/or death (rare).
  • Symptoms may last several days and may be fatal.
  • Call 911. First aid- perform CPR, emesis (vomiting) followed with activated charcoal.

Drug Interactions:

  • Foxglove should not be used in conjunction with medications or plants that deplete potassium including: Anthraquinone glycoside containing plants (laxatives) Quinidine, Glycyrrhiza, non-potassium sparing diuretics and corticosteroids.
  • Caution with use of other cardiac glycoside containing plants due to additive effects.
  • Possible additive effects when taken with hawthorne/Crataegus—can use to decrease patient’s dose of Digitalis

Safety:

  • Contraindicated in pregnancy and lactation
  • Continuous internal use of whole leaf is contraindicated due to toxic glycosides. Drug form is preferred (digoxin)

 

Preparation and Dosage:

  • The whole Digitalis plant or plant extracts are generally not used due to toxicity
  • Dosage ranges of digoxin (drug medication) are variable according to the degree of heart failure and the age of the patient
  • Typical dosage range of 12 – 35 mcg/kg body weight. The maintenance daily dosage for most patients is between 0.25-0.5 mg every day.

 

Are you interested in reading about more herbs? Click here to check out more articles!

 

References:

Digoxin Uses, Dosage & Side Effects – Drugs.com. (2020). Drugs.com. Retrieved 27 May 2020, from https://www.drugs.com/digoxin.html

Kreis, W. (2017). The Foxgloves (Digitalis) Revisited. Planta Medica, 83(12/13), 962-976. doi:10.1055/s-0043-111240 https://www.thieme-connect.com/products/ejournals/abstract/10.1055/s-0043-111240

Whayne, T. (2018). Clinical Use of Digitalis: A State of the Art Review. American Journal Of Cardiovascular Drugs, 18(6), 427-440. doi:10.1007/s40256-018-0292-1https://link.springer.com/article/10.1007%2Fs40256-018-0292-1

Khan, M., Chesney, J., Laber, D., & Miller, D. (2009). Digitalis, A Targeted Therapy for Cancer?. The American Journal Of The Medical Sciences, 337(5), 355-359. doi:10.1097/maj.0b013e3181942f57 https://www.amjmedsci.org/article/S0002-9629(15)31997-2/fulltext