digoxin, Lanoxin

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Pharmacy Author:

Omudhome Ogbru, PharmD

Omudhome Ogbru, PharmD

Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

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Medical and Pharmacy Editor:

Jay W. Marks, MD

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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GENERIC NAME: digoxin

BRAND NAME: Lanoxin

DRUG CLASS AND MECHANISM: Digoxin increases the strength and vigor of heart contractions, and is useful in the treatment of heart failure. It is extracted from the leaves of a plant called digitalis lanata. Digoxin increases the force of contraction of the muscle of the heart by inhibiting the activity of an enzyme (ATPase) that controls movement of calcium, sodium and potassium into heart muscle. Calcium controls the force of contraction. Inhibiting ATPase increases calcium in heart muscle and therefore increases the force of heart contractions. Digoxin also slows electrical conduction between the atria and the ventricles of the heart and is useful in treating abnormally rapid atrial rhythms such as atrial fibrillation, atrial flutter, and atrial tachycardia. (Abnormally rapid atrial rhythms can be caused by heart attacks, excessive thyroid hormones, alcoholism, infections, and many other conditions.) During rapid atrial rhythms, electrical signals from the atria cause rapid contractions of the ventricles. Rapid ventricular contractions are inefficient in pumping blood containing oxygen and nutrients to the body, causing symptoms of weakness, shortness of breath, dizziness, and even chest pain. Digoxin alleviates these symptoms by blocking the electrical conduction between the atria and ventricles, thus slowing ventricular contractions. The FDA approved digoxin in 1975.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Tablets: 0.125, and 0.25 mg; Elixir: 0.05, 0.25, and 0.1 mg/ml.

STORAGE: Digoxin should be stored at room temperature, 59-86 F (15-30 C) and protected from light.

PRESCRIBED FOR: Digoxin is used for mild to moderate congestive heart failure and for treating an abnormal heart rhythm called atrial fibrillation.

DOSING: Digoxin may be taken with or without food. Digoxin is primarily eliminated by the kidneys; therefore, the dose of digoxin should be reduced in patients with kidney dysfunction. Digoxin blood levels are used for adjusting doses in order to avoid toxicity. The usual starting dose is 0.0625-0.25 mg daily depending on age and kidney function. The dose may be increased every two weeks to achieve the desired response.

DRUG INTERACTIONS: Drugs such as verapamil (Calan, Verelan, Verelan PM, Isoptin, Isoptin SR, Covera-HS), quinidine (Quinaglute, Quinide), amiodarone (Cordarone), indomethacin (Indocin, Indocin-SR), alprazolam (Xanax, Xanax XR, Niravam), spironolactone (Aldactone), and itraconazole (Sporanox) can increase digoxin levels and the risk of toxicity. The co-administration of digoxin and beta-blockers [for example propranolol (Inderal, Inderal LA) or calcium channel blockers (for example, verapamil), which also reduces heart rate, can cause serious slowing of the heart rate.

Diuretic-induced [for example, by furosemide (Lasix)] reduction in blood potassium or magnesium levels may predispose patients to digoxin-induced abnormal heart rhythms.

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