GS-441524

What is GS-441524?

GS-441524 is an antiviral medication used to treat feline infectious peritonitis (FIP).

There are currently no products containing GS-441524 that are approved by the Federal Drug Administration (FDA) or by Health Canada. There is a formulation approved in the United Kingdom. 

The FDA has approved the compounding of this medication by one pharmacy that has an agreement to import the medication. Health Canada has approved importation of the UK medication with emergency drug release documentation.

Always follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.

How is GS-441524 given?

• GS-441524 is given by mouth in the form of a tablet or a liquid suspension. 
• Use appropriate hand hygiene when handling this medication.
• Give this medication 30–60 minutes before a meal. 
• If vomiting occurs when dosed on an empty stomach, give future doses with a treat or small amount of food. 

This medication should take effect quickly and improvement in clinical signs may be seen in as few as 2 to 5 days with obvious improvement in 1–2 weeks. During the first 1–2 weeks, additional FIP-related clinical signs may appear.

What if I miss administering a dose of GS-441524?

• 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 your cat two doses at once.

Are there any potential side effects?

GS-441524 may cause the following side effects:

• Reaction at the injection site (i.e., redness or swelling)
• Mild increase in one liver enzyme (ALT)
• Mild elevations in some white blood cell lines (eosinophils, lymphocytes)
• Bladder stones composed of GS-441524 have been reported in cats receiving unlicensed formulations of the medication

Drug sensitivities can develop over time, with repeated exposure. Your cat 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 24 hours, although effects may be longer in cats with liver or kidney disease. 

Are there any risk factors for this medication? 

DO NOT USE in cats who are: 

• Allergic to it or medications like it, such as remdesivir

USE WITH CAUTION in cats who are:

•  Pregnant or nursing

More risk factors may be revealed with increased use of the product. Consult with your veterinarian if you are concerned about its use for your cat

Are there any drug interactions I should be aware of? 

There are no known interactions at the time of publishing. It is important to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your cat is taking before starting any new treatment.

Is any monitoring needed with this medication? 

• Regular monitoring is important to ensure effective dosing. 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.
• Monitor your cat closely for any changes, including improvements or side effects such as those noted above. Contact your veterinarian with any changes.

How do I store GS-441524?

• Store the product according to the instructions on the compounded medication (often room temperature between 59°F and 86°F (15°C and 30°C), but make sure you follow the label instructions).
• Keep the container out of reach of children and pets.  
• Ask your veterinarian for specific disposal instructions. Do not flush medicines down the sink or toilet unless instructed to do so.

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.