What is atovaquone?

Atovaquone (brand names: Mepron®, Malanil®, Wellvone®) is a drug used to treat infections caused by protozoa (single-celled organisms that cause disease). It is often combined with other drugs to treat specific infections.

In cats, it is used off-label in combination with azithromycin to treat cytauxzoonosis. In dogs, it is used off-label in combination with azithromycin to treat Babesia. It may be prescribed to treat other infections in dogs such as pneumocystosis.

Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.

How is atovaquone given?

• Atovaquone comes as a liquid suspension.
• Before using, shake the bottle gently.
• Measure the medication carefully. The liquid is thick, so allow the medication to sit in the syringe so that air bubbles can settle out and be eliminated to ensure proper dosage.
• Give atovaquone with food that is high in fat to help with absorption of the drug. Your veterinarian can recommend a canned pet food.

This medication can take a few weeks before full effects are noted, but gradual improvements are usually noticeable.

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. However, 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?

There are no known side effects from atovaquone in animals. However, reactions can occur. If any of the following signs develop, stop giving atovaquone and contact your veterinarian immediately:

• Persistent vomiting or diarrhea
• Skin rashes

Drug sensitivities can develop over time, with repeated exposure. Your pet may have no reaction after the first few doses but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment.  

Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This long-acting medication may last up to six weeks and may last longer in pets with kidney or liver disease.

Are there any risk factors for this medication?

DO NOT USE atovaquone in:

• Pregnant animals
• Animals that are allergic to the medication

USE WITH CAUTION in:

• Animals with malabsorption syndromes
• Animals that cannot take the medication with food

Are there any drug interactions I should be aware of?

Several medications should be used with caution when given with atovaquone, including:

• Certain antibiotics and anti-nausea drugs (can reduce the effectiveness of atovaquone)

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

Is any monitoring needed with this medication?

• No specific monitoring is necessary.
• Your veterinarian will let you know when and how they want to reassess your pet to ensure the medication is working and not causing side effects.
• Blood work during therapy may be recommended.
• At home, monitor for any side effects such as those noted above. If any occur, stop using the medication and contact your veterinarian.

How do I store atovaquone?

• Store atovaquone at room temperature of 59°F-77°F (15°C-25°C), in a tight container, and protected from light.
• Do not freeze this medication.

What should I do in case of an 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. Be prepared to provide information about the product and your pet's weight and symptoms.