Master List of Poisonous Plants

Foxglove (Digitalis)

Foxglove/Digitalis

Info about plant-

Digitalis is a genus of about 20 species of herbaceous perennials, shrubs, and biennials commonly called foxgloves.

This genus is native to western and southwestern Europe, western and central Asia and northwestern Africa. The scientific name means "finger-like" and refers to the ease with which a flower of Digitalis purpurea can be fitted over a human fingertip. The flowers are produced on a tall spike, are tubular, and vary in colour with species, from purple to pink, white, and yellow. The flowers can also possess various marks and spottings. The first year of growth produces only the stem with its long, basal leaves. During the second year of the plant's life, a long, leafy stem from 50 to 255 centimetres tall grows atop the roots of healthy plants.

Toxicity/Symptoms

Digitalis toxicity (Digitalis intoxication) results from an overdose of digitalis and causes-

· nausea

· vomiting

· diarrhea

· as well as sometimes resulting in xanthopsia (jaundiced or yellow vision)

· blurred outlines (halos)

· drooling,

· abnormal heart rate

· cardiac arrhythmias

· weakness

· collapse

· dilated pupils

· tremors

· seizures

· and even death.

Bradycardia also occurs. Because a frequent side effect of digitalis is reduction of appetite, some individuals have used the drug as a weight-loss aid.

The entire plant is toxic (including the roots and seeds). Mortality is rare, but case reports do exist. Most plant exposures occur in children younger than six years and are usually unintentional and without associated significant toxicity. More serious toxicity occurs with intentional ingestions by adolescents and adults.

Early symptoms of ingestion include-

· nausea

· vomiting

· diarrhea

· abdominal pain

· wild hallucinations

· delirium

· severe headache.

Depending on the severity of the toxicosis, the victim may later suffer-

· irregular and slow pulse

· tremors

· various cerebral disturbances, especially of a visual nature (unusual colour visions (see xanthopsia) with objects appearing yellowish to green, and blue halos around lights),

· convulsions

· deadly disturbances of the heart.

Digitalis poisoning can cause heart block and either bradycardia (decreased heart rate) or tachycardia (increased heart rate), depending on the dose and the condition of one's heart. Notably, the electric cardioversion (to "shock" the heart) is generally not indicated in ventricular fibrillation in digitalis toxicity, as it can increase the dysrhythmia. Also, the classic drug of choice for ventricular fibrillation in emergency setting, amiodarone, can worsen the dysrhythmia caused by digitalis, therefore, the second-choice drug lidocaine is more commonly used.

Medicinal uses

Cardiac

A group of medicines extracted from foxglove plants are called digitalin. The use of D. purpurea extract containing cardiac glycosides for the treatment of heart conditions was first described in the English-speaking medical literature by William Withering, in 1785, which is considered the beginning of modern therapeutics. It is used to increase cardiac contractility (it is a positive inotrope) and as an antiarrhythmic agent to control the heart rate, particularly in the irregular (and often fast) atrial fibrillation. Digitalis is hence often prescribed for patients in atrial fibrillation, especially if they have been diagnosed with congestive heart failure. Digoxin was approved for heart failure in 1998 under current regulations by the Food and Drug Administration on the basis of prospective, randomized study and clinical trials. It was also approved for the control of ventricular response rate for patients with atrial fibrillation. American College of Cardiology/American Heart Association guidelines recommend digoxin for symptomatic chronic heart failure for patients with reduced systolic function, preservation of systolic function, and/or rate control for atrial fibrillation with a rapid ventricular response. Heart Failure Society of America guidelines for heart failure provide similar recommendations. Despite its relatively recent approval by the Food and Drug Administration and the guideline recommendations, the therapeutic use of digoxin is declining in patients with heart failure—likely the result of several factors. Safety concerns regarding a proposed link between digoxin therapy and increased mortality in women may be contributing to the decline in therapeutic use of digoxin.

Variations

A group of pharmacologically active compounds are extracted mostly from the leaves of the second year's growth, and in pure form are referred to by common chemical names, such as digitoxin or digoxin, or by brand names such as Crystodigin and Lanoxin, respectively. The two drugs differ in that digoxin has an additional hydroxyl group at the C-3 position on the B-ring (adjacent to the pentane). Both molecules include a lactone and a triple-repeating sugar called a glycoside.