Digoxin

Overview

Overview

Lanoxin is among the most frequently prescribed drugs in this country.

It is a digitalis heart medicine that to this day is derived from the leaves of a plant related to foxglove. Digitalis has been used medically for over 200 years.

Lanoxin is prescribed for congestive heart failure and certain irregular heart rhythms, or arrhythmias.

People with heart failure often experience fluid retention, sensitivity to cold, fatigue and difficulty breathing after mild exercise, and a nighttime cough, especially when they lie down.

Lanoxin works partly by increasing the pumping power of the heart. It can also help slow an abnormal heart when atrial rhythms gets out of control. But Lanoxin is complex to manage, especially in older people.

This medication requires careful monitoring to prevent an overdose as the therapeutic level is very close to the toxic dose. Periodic blood tests are crucial.

Side Effects and Interactions

Signs of igitalis toxicity include loss of appetite, nausea, diarrhea, vomiting, stomach pain, blurred or disturbed color vision, headache, drowsiness, fatigue, and muscle weakness.

If any of these symptoms occur, contact your physician immediately.

Other adverse reactions may include personality change, depression, confusion, disorientation, apathy, bad dreams and hallucinations. Any side effects should be brought to a doctor's attention promptly.

Lanoxin can interact with a wide range of over-the-counter and prescription medications. Antacids, for example, may diminish the proper absorption of digoxin.

So can certain diarrhea medicines and drugs to control cholesterol like Questran, Cholybar or Colestid.

A number of other medications, such as Cordarone, Rhythmol and quinidine drugs, may make Lanoxin more toxic.

So can Sandimmune, used to prevent transplant rejection.

Calcium-blocking blood pressure medicines like Procardia, Cardizem CD or Calan SR may also increase digoxin levels dangerously.

Diuretics like Lasix are often prescribed in conjunction with Lanoxin. A patient taking both medicines should be monitored carefully, however, as the diuretic may make the body lose too much potassium or magnesium. This could lead to serious changes in heart rhythm.

Potassium-sparing diuretics such as Aldactazide or Moduretic could make monitoring and interpreting tests far more complicated.

One of the trickiest interactions is that of Lanoxin with erythromycin and tetracycline. For reasons that are not well understood, about one person in ten harbors bacteria in the gut that metabolizes digoxin. If this intestinal flora is wiped out with an antibiotic, the person may suddenly be exposed to much more Lanoxin than usual, even though they may still be swallowing the exact same dose.

Because of these possible complications, never add any other prescription or over-the-counter medications to Lanoxin without first checking with your pharmacist and physician.

Extracts of the herb hawthorn may increase the activity (but not necessarily the toxicity) of cardiac tonics such as digitalis.

Hawthorn is not recommended for people who are taking Lanoxin or other digoxin medications.

Licorice can greatly increase potassium loss when taking medicines such as Lanoxin; severe potassium loss greatly increases the risk of heart rhythm irregularities in people taking Lanoxin.

The herb cascara_sagrada taken with Lanoxin also could result in excessive potassium loss with resulting heart rhythm irregularities.

The herb St. John's wort can speed elimination of digoxin from the body, which could reduce its effectiveness.

Psyllium can affect the absorption of Lanoxin; if you take it, it is best to do so at least an hour after taking Lanoxin.

The herb ma huang is incompatible with cardiac glycosides such as Lanoxin; serious disruption of heart rhythm may occur.

Never stop taking Lanoxin or switch to another brand of digoxin unless your physician is monitoring closely. Because the effective dose is so close to the toxic dose, this might be dangerous.

Special Precautions

People with reduced kidney function generally require less Lanoxin. As people age their kidneys may no longer process this medicine as efficiently. This is another reason why periodic blood tests for digoxin levels are essential.

It is also crucial to monitor both potassium and magnesium levels. If these essential minerals become depleted because of diuretic therapy, Lanoxin can become extremely dangerous. Blood tests are the only way to determine electrolyte levels.

Taking the Medicine

It is usually recommended that Lanoxin be taken at the same time and in the same way each day.

For many people the most convenient time is with breakfast. However, food high in bran may reduce the absorption of this drug.

If your breakfast tends to be high in such foods, you might want to schedule your Lanoxin for another time of day.