Digoxin interactions to avoid

Drug interactions | Food interactions | Other interactions | Avoiding interactions | When to see a doctor

Digoxin has a long history, beginning over 200 years ago when its cardiac effects were first described as a digitalis or foxglove plant component. Current use is fading as other options for heart disease and the treatment of atrial fibrillation (irregular heartbeat) and congestive heart failure (CHF) are more highly recommended. One reason for waning enthusiasm for digoxin and its brand-name counterpart, Lanoxin, is that their levels in the body are notoriously disturbed by other drugs or health conditions. These interactions can push digoxin levels out of a safe and effective range and into a danger zone where adverse effects predominate. Despite these features, the cardiac glycoside drug remains in use. Digoxin can be taken safely if you know the potential interactions and take steps to avoid them.

Digoxin drug interactions

Digoxin is said to have a narrow therapeutic range, meaning that its dosing needs to hit the sweet spot between an ineffective amount and a toxic dose. All too often, other drugs can push it out of that range.

P-glycoprotein inhibitors

An assortment of medications can inhibit the P-glycoprotein transporter. Without the action of that transporter, we have trouble eliminating digoxin, and toxicity can ensue. Because there is a wide assortment, there is no single drug class to remember to avoid. Examples include:

• Quinidine
• Ketodan (ketoconazole)
• Sporanox (itraconazole)
• Paxlovid (nirmatrelvir and ritonavir)
• Clarithromycin

P-glycoprotein inducers

Conversely, any drug that induces P-glycoprotein action can diminish digoxin concentrations and effectiveness. This can be just as important if digoxin is being counted on to regulate a critical cardiovascular condition. The list of agents in the inducer category includes:

• Tegretol (carbamazepine)
• Dilantin (phenytoin)
• Rifadin (rifampin)

Whether taking an inhibitor or inducer of P-glycoprotein, you should inquire about the benefits and risks of digoxin before taking it. Your healthcare provider may determine what monitoring is required or decide on an alternative to digoxin. Using a SingleCare prescription discount card may help if seeking a lower-cost alternative.

Diuretics

Flushing fluid from our system with a diuretic could be necessary for fluid overload states like CHF. However, these water pills can also wash out electrolytes like potassium and magnesium. Hypokalemia (low potassium) and hypomagnesemia (low magnesium) can both magnify digoxin effects on the heart, potentially triggering arrhythmias. Calcium is another electrolyte whose concentration can be disturbed by diuretics and which can perturb digoxin’s actions on cardiac tissue. Possibly problematic water pills include:

• Hydrochlorothiazide (HCTZ)
• Metolazone
• Chlorthalidone
• Lasix (furosemide)
• Bumex (bumetanide)
• Aldactone (spironolactone)

Because diuretics and digoxin are beneficial therapies for CHF, situations may arise when they need to be used concurrently. Get the medical advice of your healthcare team to determine how often the levels of electrolytes and digoxin need to be monitored.

Antacids

Digoxin levels that are subtherapeutic can be a problem. Think of an arrhythmia like atrial fibrillation and the tachycardia that could result when it is not properly controlled. Antacids like Gaviscon (aluminum hydroxide/magnesium trisilicate) and Mylanta Maximum Strength (aluminum hydroxide/magnesium hydroxide/simethicone) can reduce the intestinal absorption of digoxin if taken concurrently, thereby dropping drug levels in the bloodstream. Your medical provider or pharmacist could guide you on separating digoxin and antacid doses.

NSAIDs

NSAID use is so commonplace that many of us do not even think of it when listing our medication. With many being over-the-counter, NSAIDs can easily be turned to for joint or muscle pain or headaches. They are by no means harmless and can have adverse effects on our stomach and kidneys. 

NSAIDs also interact with several drugs, including digoxin. They can lead to higher digoxin levels, putting you at risk of the side effects of digoxin, like visual changes, nausea, delirium, and arrhythmias. Ask your healthcare provider about how these risks pertain to you if taking NSAIDs like the following:

• Aspirin
• Ibuprofen
• Naprosyn (naproxen)
• Meloxicam

Heart rate and rhythm drugs

Combining digoxin with other pills that alter heart rate or heart rhythm is not uncommon. However, it must be done carefully to avoid bradycardia (an abnormally slow heartbeat) and arrhythmia. Classes to watch out for include beta blockers, antiarrhythmics, and nondihydropyridine calcium channel blockers, such as these agents.

• Inderal LA (propranolol extended-release)
• Toprol XL (metoprolol)
• Pacerone (amiodarone)
• Flecainide
• Quinidine
• Verelan (verapamil)
• Cardizem CD (diltiazem)

Digoxin food interactions

By now, you likely understand that digoxin is a tricky medication. Adding to this complexity is the fact that having food in your stomach can be harmful when taking your digoxin dose. The dose may also not get absorbed, particularly if there is much fiber or bran in your recent meal. Being consistent and taking digoxin on an empty stomach may be recommended by your pharmacist. As a side note, prescription Questran (cholestyramine) and the over-the-counter anti-diarrheal Kaopectate (kaolin) can reduce digoxin absorption in a similar manner.

Other digoxin interactions

Health conditions and supplements can have an impact on prescription drug effects. This is certainly the case with digoxin

Digoxin and St. John’s Wort

St. John’s Wort is a supplement often used for depression. It is an excellent example of the hidden hazards of dietary supplements. St. John’s Wort can interact with many prescription drugs, including digoxin. By inducing the P-glycoprotein transporter, St. John’s Wort can reduce digoxin levels, making it less effective. Make sure to let your doctor and pharmacist know about all the supplements you’re taking.

Digoxin and kidney disease

Impaired renal function can lessen the body’s clearance of digoxin. When drug levels rise as a result of kidney disease, digoxin toxicity can follow. Your medical provider may have you monitor, adjust, or avoid digoxin, depending on the extent of your renal impairment.

Digoxin and thyroid disease

Digoxin levels are also affected by thyroid function. As thyroid function rises naturally or when taking thyroid replacement pills like Synthroid (levothyroxine), the bodily concentration of digoxin can decrease. Monitoring and changing digoxin dosing may be necessary in these circumstances.

Digoxin and Wolff-Parkinson-White syndrome

Life-threatening heart arrhythmias are the major fear in Wollf-Parkinson-White (WPW) syndrome. In people with the syndrome, the critical rhythm problem of ventricular fibrillation can be triggered by digoxin. The use of cardiac glycoside is avoided in WPW.

Digoxin and pregnancy and breastfeeding

Being an older drug is an advantage of digoxin in some ways. There has been plenty of time for digoxin to be used in different health-related scenarios, including pregnancy and breastfeeding, and be monitored for adverse effects. If there is a sufficient need for digoxin, your healthcare provider may have you continue it while pregnant or breastfeeding.

How to minimize digoxin interactions

Simply recognizing that digoxin interacts with many things is a good start. Knowing this puts you on guard for problems. Having a system to avoid interactions is a great next step. Your process should involve a list of all your prescription drugs, over-the-counter medications, supplements, and medical conditions. Keep that list updated, and share it with your healthcare team. Finally, ask your prescribing providers and pharmacists to review the list for any interactions involving digoxin.

When to talk to a healthcare provider about digoxin interactions

Safe and effective digoxin therapy requires you to be diligent for the drug to stay within its narrow therapeutic range. Part of what is required of you is a regimented dosing schedule and follow-up for monitoring. Another important task is regular communication about digoxin interactions. That means you should ask your healthcare provider to address this concern when digoxin is first prescribed, regularly throughout treatment, and when a new drug is added. Direct questioning about drug interactions can make all the difference.