Molnupiravir

What is molnupiravir?

Molnupiravir is an antiviral drug used to treat feline infectious peritonitis (FIP) in cats.

It is used off label (extra label) in veterinary medicine. 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 very carefully, as their directions may be significantly different from those on the label.

How do I give my pet molnupiravir?

• Molnupiravir comes in capsule form. 
• Capsules are given orally (by mouth). 
• This medication may be given with or without food.
• If vomiting occurs when dosed on an empty stomach, give future doses with food or a treat. 
• Follow the instructions on the product label, in conjunction with your veterinarian’s directions.

Effects of this medication may not be seen for 1–2 weeks. 

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?

Molnupiravir may cause the following side effects:

• Lack of appetite or energy
• Drooling or vomiting
• Folded ear tips or brittle whiskers

Serious adverse reactions may occur. If any of the following signs develop, stop giving molnupiravir and contact your veterinarian immediately:

• An allergic reaction such as irregular breathing, rash, fever, puffiness and swelling around the face

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 short-acting medication should stop working within 1–2 days, though effects may last longer in pets with kidney and/or liver disease.

Are there any risk factors for this medication?

DO NOT USE molnupiravir in:

• Cats that are allergic to any component of the medication
• Cats that are pregnant, nursing, or used for breeding

USE WITH CAUTION in:

• Young cats

Are there any drug interactions I should be aware of?

No known drug interactions have been reported for this medication. Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.

Is any monitoring needed with this medication?

• Your veterinarian may recommend baseline and periodic blood tests.
• 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 molnupiravir ophthalmic?

• Store in a tightly sealed container at room temperature of 68°F–77°F (20°C–25°C).
• Protect from light.
• Store compounded forms of this medication according to the label.
• Keep medication out of reach of children and pets.

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. Be prepared to provide information about the product and your pet's weight and symptoms.