A cure for FIP: antiviral agents GS-441524 and GC376?


In this article I check out 2 similar treatments for the devastating domestic cat disease Feline Infectious Peritonitis – FIP. You can read about the disease in plain language by clicking on this link (it opens a new tab/page so you’ll stay on this page).

Update 4th Aug 2023: A study dated Oct 2022 is titled: Unlicensed Molnupiravir is an Effective Rescue Treatment Following Failure of Unlicensed GS-441524-like Therapy for Cats with Suspected Feline Infectious Peritonitis. It tells the story. Link: https://doi.org/10.3390%2Fpathogens11101209

I wrote about these treatments some time ago but at that time I had little information. I have joined the respected closed Facebook group ‘FIP Fighters‘ to educate myself and have read two excellent if not lengthy articles on the subject. There is another Facebook group called ‘FIP Warriors‘. I’d certainly advise cat guardians with FIP cats to check out these groups. They are probably the best source of information on these antiviral treatments as you’ll get first hand experiences as well as the research. It’s all from the front line of FIP treatment.

FIP cat
FIP cat. Photo: Setiya Veterinary Hospital.
Two useful tags. Click either to see the articles:- Toxic to cats | Dangers to cats


If I were to try and summarise these treatments I’d probably say that a lot of hope and expectation was generated by the tests run by a veterinarian, Professor Niels Pedersen of the University of California, Davis, and his team. He picked up on the human antiviral treatment, GS-5734, which proved effective in preventing ebola in rhesus monkeys.

Pedersen wanted to see if he could achieve success in treating FIP cats using the less chemically complex ‘GS-441524’. The results were very optimistic. They offered hope for a cure of these killer feline disease.

The health of 26 out of 31 FIP cats improved dramatically. Their fever was resolved in 12 to 36 hours. Their appetite improved and they gained weight. 24 of the 26 remained healthy. 8 relapsed and were successful treated with further rounds of the same treatment.

Pedersen wrote:

‘FIP has been my fascination for the past 50 years and I am fortunate to have reached a final stage in my career having identified safe and effective antiviral drugs. We now know that small molecules targeting specific steps in RNA virus replication are capable of safely curing various forms of FIP.’

However, he cautioned that the test results cannot be translated into commercial available products at that time (Feb 2019)


Moving forward to the present (Aug 2019) it’s clear from the excellent document on this treatment (and others) on the FIP Fighters Facebook website that GS441524 and GC376 are only available on the black market.

Please click this link to see the FIP Treatments including GS-441524. It is called: FIP DIAGNOSTICS AND TREATMENT SUMMARY DIAGNOSTICS

The document sums up the current situation:

“These compounds may be approved in the future for use in cats with FIP but they are not approved by the FDA, or by any other international regulatory body, at the present time. This means they can’t be prescribed by your veterinarian. The compounds on the black market in China are not monitored to strict safety standards, as they were in the clinical trials. Some of the GS compounds have reportedly been tested for biological activity against FIP virus, and found to be comparable in activity to the compound used in Dr Pedersen’s clinical trial.”

I’d encourage carers of FIP cats to join these FB groups and learn. There is a very strong warning/disclaimer on the FIP Warriors FB page which gives the clue that these treatments are not authorised by the authorities in the USA. You’ll be getting the medication from China. Can you trust it? I certainly would not. When you combine the eager need by cat owners to find a cure or treatment for their FIP cats with the exploitative nature of drug producers you can see that it is possible for these black market drugs to be of poor quality and of no use. Big profits are involved.

There is also the matter of the extreme cost of these drugs. It is stated that the costs of a 12 week course is $1,500 to $8,000. These are injections. Nowadays you can get pills at $16 per pill (see the linked document). No everyone – relatively few – can afford these treatments.

However, FIP Warriors state:

“We do not commercialize or promote any GS products, however, we are not aware of any unreasonable risk related to GS products and we believe that GS-441524 does satisfy GRASE criteria established for animal drugs by the FDA….”

My conclusion is that GS-441524 is better than GC376 and that it brings hope to many. There is a degree of success and it is worth checking out. You’ll need deep pockets and there is some risk. I have read some disappointments because the results have not been to expectation. Perhaps the expectations are too high.

6 thoughts on “A cure for FIP: antiviral agents GS-441524 and GC376?”

  1. My family lost two cats to FIP in the 1980’s. I would’ve thought cures and preventions would’ve been developed and available and inexpensive well before now.

  2. I have a friend who adopted an abandoned kitten and it is now 14 weeks. There was evidence of a swollen belly at about 4 weeks but it was attributed to feeding cat milk and wet kitten food simultaneously. Subsequent to a second treatment for worms at about 8 weeks, the swelling was somewhat worse but the doctor seemed to think the kitten was just a bit chubby. Since that date, the kitten has lost 1 lb from the five at the last vet visit and is now 4 lbs and is just being tested for FIP. Apart from any drug trials and advocacy, which disturbs me as my father had been a proponent of laetrile, does anyone have a sense of whether at this stage and age there might be the possibility of positive results: I guess I mean is it too late?

  3. I am glad that progress has been made. I had a ten-month old kitten, Nylan, succumb to FIP back in August. In July, he was fine, but went downhill fast in August, and there was nothing that we could do.


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