Digoxin

By Lauren R. Forsythe, PharmD, MBA, DICVP; 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.

"Many drugs are commonly prescribed for off-label use in veterinary medicine."

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 carefully, as they 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 can also be given by injection in the hospital.
  • It can be given with or without food. 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 easily overdosed. 

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 as soon as you remember, and then continue with the regular dosing schedule. If it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once.

Are there any potential side effects?

Side effects include:

  • vomiting, diarrhea, and lack of appetite
  • weight loss
  • tiredness
  • behavior changes

Serious side effects include:

  • collapse
  • severe tiredness 
  • 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 
  • pets that already have too much digoxin in the bloodstream
  • pets with certain arrhythmias such as ventricular fibrillation 
  • cats with hypertrophic cardiomyopathy

Digoxin should be USED WITH EXTREME CAUTION in pets with:

  • kidney disease
  • heart failure
  • subaortic stenosis

Digoxin should be USED WITH CAUTION in pets that:

  • have lung disease
  • have low oxygenation
  • have electrolyte imbalances
  • have severe thyroid disease
  • have certain heart conditions (e.g., acute myocardial infarction, frequent ventricular premature contractions, chronic constrictive pericarditis, increased carotid sinus sensitivity, or high-grade atrioventricular block)
  • are pregnant or lactating

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with digoxin:

  • amlodipine
  • amiodarone
  • antacids
  • anticholinergics
  • beta-blockers
  • chloramphenicol
  • cyclosporine
  • diazepam
  • diltiazem
  • enalapril
  • fluoxetine
  • furosemide
  • ketoconazole/itraconazole
  • metoclopramide
  • nonsteroidal anti-inflammatory drugs (NSAIDs)
  • omeprazole
  • phenobarbital
  • potassium affecting drugs
  • St. John’s wort
  • sulfasalazine
  • telmisartan
  • thiazide diuretics
  • thyroid supplements
  • trazodone
  • trimethoprim

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

Is any monitoring needed 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).
  • 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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