Digitalis has been associated with medecine for more than 200 years. A number of species of Digitalis genus are available, of which D.purpurea (purple foxglove) and D.lanata (Grecian foxglove) are the most common and abundant. Others include-D.thapsi (Spanish foxglove), D.lutea (straw foxglove).This biennial herb of Scrophulariaceae plant family was introduced into British medicine for treatment of dropsy by Botanist William Withering. It is commonly known as foxglove-deriving it name from the flowers which resemble the fingers (digits)of a glove. Other common names like Witch’s glove, Dead Man’s Bells etc signify its toxic nature. You can find this plant in Europe and North America while Holland and Eastern Europe are its commercial producers.
Why is Digitalis Unique?
All the species of digitalis owe their uniqueness to the presence of extraordinarily bioactive compounds known as cardiac glycosides (chemical compounds containing a sugar molecule linked to nonsugar steroid part) namely digoxin, digitoxin. These resemble chemically the digitalis-like compounds endogenously produced in the human body which have inherent cardiotonic property (increasing strength and pumping ability of muscles of heart) and also regulating cell growth and cell death. Besides, Digitalis also shows antioxidant property which is due to natural compounds called Flavanoids. D.lanata contains some compounds which are 300 times more potent than D.purpurea
Health Benefits of Digitalis
The majority health benefits of Digitalis are attributed to its heart stimulation properties and hence it is known in Sanskrit as “Hrtpatri” (leaves used for heart ailments).
Digitalis in Congestive heart failure : In most of the countries, coronary and associated circulatory and heart disorders now constitute the principle cause of human mortality. The leaves of Digitalis are rich in glycosidic content and hence are used commercially for heart ailments. Digitalis has a positive inotropic effect (increase the strength of heart muscle contraction) on the failing heart. This effect is due to the presence of glycosides which bind and inhibit an enzyme in heart muscles and this action initiates contraction (normal pumping) of heart thereby maintaining a steady and strong heartbeat. This clinical activity depends on both the sugar and nonsugar part of the glycoside.
Sometimes an imbalance in sodium-potassium levels in body causes water retention and leads to swelling (edema) in foot which acts as an obstacle due to which you are not able to walk properly and indirectly pressure on your heart increases because it has to pump with more force to circulate blood. Digitalis(along with other drugs) rescues in such situations by promoting the overall activity of heart tissues by affecting these minerals (sodium ,potassium ,calcium) in heart muscle cells. This manifests as greater output per beat and complete emptying of heart. And due to this, the delayed circulation in congestive heart failure is improved and edema is flushed out. Hence in modern medicine digitalis finds an important place in congestive heart failure. Treatment of heart failure thus helps you to maintain your walk and normal exercise ability. The strain on heart is reduced and normal strength is maintained and improved. Various other mechanisms also contribute to bring about an overall effectiveness of Digitalis in heart failure.
Digitalis for irregular heart beats : Digitalis has a potential to normalize the conduction disturbances during arrhythmias (irregular heartbeats).A number of studies have been conducted to verify use of digitalis for treating sinus rhythm. During impairment in circulation due to abnormal heartbeats, digitalis helps by restoring heart’s function. Digitalis has negative chronotropic effect (slowing down of heart rate) by direct suppression of electrical impulse conduction throughout the atria ventricle node. So another major use of Digitalis is in controlling abnormal contractions of ventricles during Atrial flutter (atrial beating abnormal about 200/min) and Atrial fibrillation (asynchronous activation of atrial muscle cells leading to abnormal beats about 350-370/min) and premature extra beats. Also increased risk of blood clots due to irregular heartbeats can be overcome by digitalis thereby decreasing the risk of heart attack or stroke.
Digitalis in cancer : The anticancer activity of digitalis has been attributed to the flavanoid and glycoside content in the drug. Acute studies on animals have shown the use of digitalis in medical oncology. Various experiments also demonstrated cytotoxic action of common species of digitalis against solid tumor cell lines even in human. However this property of digitalis demands further investigations.
Miscellaneous : Antidiabetic action has been shown in some studies on rats and is thought to be related to a saponin glycoside-digitonin. Aqueous extract of Digitalis.lanata leaves demonstrated significant antiviral action against herpes, influenza and polio virus.
Digitalis is a drug of low margin of safety which means that its clinically beneficial dose is riskily close to its toxic dose. It has a cumulative effect in body and gets slowly eliminated and therefore overdose during therapy is common. All parts of plant are toxic. Accidental ingestions in high dose have been proved lethal in both humans and animals . Toxicity may arise due to chronic overmedication, low level of potassium in body associated with diuretic use in heart failure, ailments destroying kidney functions etc. The symptoms of digitalis toxicity can be broadly categorized into two –
- Cardiac i.e. Heart related – these include precipitation of arrhythmias, conduction block, further worsening of Heart Failure and Cardiac shock.
- Non-cardiac i.e. related to other organs – These include effects like nausea, vomiting, pain in abdomen, you may also experience blurring of vision, fatigue, slowing of pulse as milder effects. However severe side effects may also be experienced such as mental confusion, tremors, convulsions, stupor and even death.
Additional symptoms that may be coupled to digitalis toxicity comprise of decreased urine output, overall edema, breathing difficulty at rest etc. Digitalis has a property of showing inter-individual response variability. This means that the level of effect produced is not same in all the individuals. Hence the dose must be regularly and effectively monitored when you are taking this medicine. Monitoring involves frequent analysis of drug concentration in the body, minerals content in body, assessment of kidney function and noting ECG (Electrocardiogram) readings. Moreover during therapy it is required that you stick to only one brand at a time as there are possibilities of variations in exact content between different brands.
Precautions While using Digitalis
Digoxin is more preferable to digitoxin by most of the physicians due to more toxic effects of digitoxin. Prior taking Digitalis preparations you must inform your doctor if you had been taking any other medicines like calcium supplements, diuretics or water pills or other drugs which are effective in the gastro-intestinal system. You should take oral medication of digitalis a couple of hours prior to or later to ingestion of foods which are high in fibers like oats, bran etc.In case of any allergic symptom noticed consult your doctor immediately. Do not use this medication without consultation of doctor. In pregnant and lactating women cardiac adverse effects are documented. Hence avoid digitalis.
Storing Digitalis and Preparations
Digitalis plant parts or its preparations must be stored in air-tight containers and protect them from light to prevent complete degradation and subsequent loss of activity.
Considering the health benefits of digitalis and its toxicology you can use digitalis in chronic heart disease but with proper regulation of therapy and consultation of doctor.