By Rania Gollakner, BS, DVM, MPH

What is digoxin?

Digoxin (brand name: Lanoxin®, Lanoxicaps®, Toloxin®, Digitek®, Digox®) is a cardiac glycoside heart medication used to treat certain abnormal heart rhythms and certain types of congestive heart failure.

Its use in cats, dogs, ferrets, and horses to treat various heart conditions is ‘off label’ or ‘extra label’. Many drugs are commonly prescribed for off label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully as their direction may be significantly different from those on the label.

How is digoxin given?

Digoxin is given by mouth in the form of a tablet or liquid, and with or without food. It can also be given by injection in the hospital setting. If your pet vomits after receiving the medication on an empty stomach, give future doses with food or a treat. Measure liquid doses VERY carefully; this drug can be overdosed very easily.

This medication will take effect quickly, in about 1 to 2 hours, and improvement in clinical signs should follow.

What if I miss giving my pet the medication?

If you miss a dose, give it when you remember, but if it is close to the time for the next dose, skip the dose you missed and give it at the next scheduled time, and return to the regular dosing schedule. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

Side effects include vomiting, diarrhea, lack of appetite, weight loss, tiredness, or behavior changes. Serious side effects include collapse, severe tiredness, or muscle weakness.

This moderate-acting medication should stop working in a few days, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

Digoxin should not be used in pets that are allergic to it or in pets that already have too much in the bloodstream. It should not be used in pets with certain arrhythmias such as ventricular fibrillation or in cats with hypertrophic cardiomyopathy. Extreme caution should be used when prescribing digoxin for use in pets with kidney disease, heart failure, or subaortic stenosis. Digoxin should be used cautiously in pets with lung disease, low oxygenation, electrolyte imbalances, severe thyroid disease, or certain heart conditions (e.g., acute myocardial infarction, frequent ventricular premature contractions, chronic constrictive pericarditis, increased carotid sinus sensitivity, or high-grade AV block). Digoxin should be used cautiously in pregnant or lactating pets.

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with digoxin: alprazolam, aminosalicylic acid, amiodarone, albuterol, aluminum hydroxide, antacids, anticholinergics, azithromycin, beta-blockers, calcium, calcium-channel blockers, carvedilol, chloramphenicol, cholestyramine, cimetidine, clarithromycin, coleus, cyclosporine, diazepam, diltiazem, enalapril, erythromycin, fluoxetine, furosemide, gentamicin, hawthorn, ketoconazole/itraconazole, metoclopramide, minocycline, neomycin, NSAIDs, omeprazole, oxytetracycline, penicillamine, phenobarbital, phenytoin, potassium affecting drugs, quinidine, reserpine, spironolactone, St. John’s wort, succinylcholine, sucralfate, sulfasalazine, telmisartan, tetracycline, thiazide diuretics, thyroid supplements, trazodone, trimethoprim, or verapamil.

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

Serum digoxin levels will be monitored, especially when starting therapy. Appetite, body weight, electrolytes, kidney function, and electrocardiograms of the heart should be monitored during therapy. Your veterinarian will monitor your pet to be sure that the medication is working.

How do I store digoxin?

Store this medication at room temperature between 59°F and 86°F (15°C and 30°C) and protect from light.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.

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