Digoxin is a medication used to strengthen your heart and combat the effects of cardiovascular problems such as heart failure and irregular heartbeat. If you eat grapefruit or drink grapefruit juice while taking digoxin, you can change the way your body processes the drug. However, interactions between this medication and grapefruit will not typically harm your health.
Digoxin Basics
Digoxin is available in the United States under the brand name Lanoxin. It achieves its effects by increasing the amount of calcium inside your heart's cells; in turn, this extra calcium allows your heart to beat more strongly and consistently, while experiencing an overall decrease in workload. People with heart failure typically see improvements in their hearts' ability to pump blood when using digoxin, while people with a form of heartbeat irregularity called atrial fibrillation typically experience both a reduction and a normalization of their average heart rate. However, it may take anywhere from a few weeks to a few months before the beneficial effects of digoxin take hold.
Increased Absorption
Certain compounds in grapefruit juice can potentially elevate your blood concentrations of digoxin by interrupting the effects of a substance in your intestines called P-glycoprotein, Drugs.com reports. Normally, P-glycoprotein limits your ability to absorb digoxin into your system. For a period of roughly 12 hours following the use of a single 0.5 mg digoxin dose, grapefruit increases absorption by approximately 9 percent when compared with the effects of digoxin taken with water. However, this level of change is not considered medically significant when judging digoxin's effects.
Reduced Absorption
The use of grapefruit juice can potentially reduce your blood concentrations of digoxin by interfering with the activity of a substance called organic anion transporting polypeptide, or OATP, according to Rubin Bressler, M.D., of the University of Arizona. Normally, the OATP in your intestines appears to help you absorb digoxin and certain other medications. However, consumption of grapefruit juice can limit the effects of OATP for at least a full day. Despite this theoretical potential for lowered absorption, studies on the subject have produced conflicting results, and grapefruit juice does not seem to lower digoxin's effectiveness in practical use.
Considerations
A number of other substances and medications can lower your body's ability to absorb and use digoxin, the American Academy of Family Physicians notes. They include aluminum- or magnesium-containing antacids, laxatives that contain psyllium or methylcellulose, cholesterol-reducing drugs such as colestipol and cholestyramine, sulfasalazine, metoclopramide and foods or supplements that contain large amounts of dietary fiber. If you take digoxin, review your medications and dietary choices with your doctor to safeguard your health and maintain the full benefits of your treatment.
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