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What is the correct dosage of GS-441524?

The dose depends on the weight of the cat. However, the basic dosage is 6-8 mg GS per 1 kg live weight of a cat in wet or dry uncomplicated FIP. Ours is also available calculator:

Neurological and ocular forms require dosages of up to about 10-12 mg / kg. Be sure to consult a specific dosage.

If you like formulas, then calculating is simple.

i = m * d / c

i: injection dose [ml]

m: cat’s weight [kg]

d: dosage of active substance (GS441524) for a given type of FIP [mg / kg]

c: concentration [mg/ml]


Cat’s weight is 2kg,

dose for your FIP type is 5mg/kg. 6mg / kg,

concentration of injection solution is 15mg / ml.

Enter into formula and you will get:

i = 2 * 6/15 = 0.8 ml

Urinary Stones in FIP Cats Treated with GS-441524: limited solubility of GS-441524

GS 441524 Urinary Stones in FIP Cats

As a devoted veterinary specialist with a deep passion for feline health, I find it crucial to address a recent and mysterious development in the world of Feline Infectious Peritonitis (FIP) treatment. The unexpected emergence of urinary stones in young cats receiving GS-441524 treatment has ignited a need for understanding and vigilance among cat owners. 

Urinary stones have long been a concern for cat owners, typically containing high levels of phosphorus, calcium, and magnesium. However, what sets these recent cases apart is the striking composition of these stones. Instead of the conventional elements, they are rich in nitrogen, carbon, and oxygen.

These stones are not your typical urinary stones, and their origin is closely tied to the use of GS-441524 in FIP treatment.

The affected cats in these cases share common traits: they are all under one year old, and they all have a history of Feline Infectious Peritonitis (FIP). FIP is a devastating disease that has perplexed veterinarians and cat owners alike, making the recent findings even more intriguing.

The diagnosis and treatment journey for these young cats reveal an essential connection to the urinary stones they developed.

GS-441524: A Closer Look

GS-441524 is an antiviral medication that holds promise in the treatment of FIP. It is this medication that stands at the heart of the urinary stone mystery. Understanding GS-441524 and its role in FIP treatment is crucial.

The medical history of the affected cats paints a clear picture of the link between this medication and the stones they developed.

Stone Analysis

To identify the culprit, stone analysis was conducted, yielding an unexpected revelation. The stones were composed of GS-441524, confirming the connection between this antiviral medication and the urinary stones.

The spectrographic match was an essential piece of evidence, confirming the composition of these atypical stones.

GS-441524 Elimination in Urine

Following GS-441524 administration, the primary elimination pathway for this medication is through the urine. This raises a critical concern, as the limited solubility of GS-441524 in aqueous solutions like water poses the risk of stone formation.

As cat owners, understanding this elimination process is vital to monitor for signs of stone formation.

GS-441524 Solubility Challenges

Following administration, GS 441524 is primarily eliminated in the urine.  Although GS 441524 is very soluble in organic solvents like DMSO (10-59mg/ml), it is sparingly soluble in aqueous solutions like water (0.0004 to 0.1 mg/ml).  Its limited solubility makes GS 441524 a prime candidate to form stones.  Observing urinary signs in cats receiving Remdesivir or GS 441524 is an indication to look for stones.  Seeing atypical crystalluria or uroliths may be an indication to limit medication dose (if possible) and increase water consumption to minimize stone formation.  

Managing Urinary Stones in FIP Cats

Early detection of urinary stone formation in FIP cats is paramount. Key indicators include atypical crystalluria and the presence of uroliths. Vigilance and regular monitoring are essential to identify these warning signs promptly.

Personal Anecdote: I recall a case where a vigilant cat owner noticed unusual litter box behavior in their FIP-diagnosed cat. Upon examination, urinary stones were discovered early, preventing further complications.

For cat owners with FIP-diagnosed cats receiving GS-441524, a proactive approach is vital. This includes considering the adjustment of medication doses if feasible. Additionally, increasing water consumption is a strategic way to minimize the risk of stone formation.

Personal Anecdote: I once worked with a cat owner who diligently adjusted their cat’s medication dose while providing plenty of water. This proactive approach significantly reduced the risk of stone formation.


The emergence of urinary stones in FIP cats treated with GS-441524 underscores the need for heightened vigilance and informed decision-making. While GS-441524 offers promise in FIP treatment, it comes with unique challenges. Cat owners should prioritize early detection of urinary stone formation, regular monitoring, and proactive measures to adjust medication doses and promote hydration.

In this intricate journey of FIP treatment, remember that your cat’s well-being is at the heart of every decision. Be informed, vigilant, and prepared to navigate the complexities of this unique challenge.

For further information and support on FIP, urinary stones, and GS-441524, consider exploring the following resources:

Passhaei Y. Analyical methods for the determination of Remdesivir as a promising antiviral candidate drug for the COVID-19 pandemic. Drug Discoveries and Therapeutics. 2020;14:273-281

Wei D. et al. Potency and pharmacokinetics of GS-441524 derivatives against SARS-CoV-2. Bioorg Med Chem.2021;46:116364

GS-441524 formula: Make GS 441524 injection & pill on your own

Focused on feline disease treatment, we understand the profound desire to explore every possible avenue when it comes to saving our beloved feline companions from the grasp of Feline Infectious Peritonitis (FIP). In this article, we will embark on an informative journey, delving into the world of GS-441524, an antiviral compound with promising potential in FIP treatment. We’ll discuss the responsible and ethical aspects of its use, empowering cat owners to make informed decisions about preparing GS-441524 at home.

What is GS-441524?

GS-441524 is a compound that has garnered significant attention in the world of FIP treatment due to its potential antiviral properties. It is closely related to another drug, Remdesivir, which gained prominence during the COVID-19 pandemic. GS-441524 holds promise in addressing the devastating effects of FIP, but its use comes with critical considerations.

To comprehend the power and potential of GS-441524, it’s crucial to explore its molecular structure and mechanism of action. GS-441524 functions as a nucleoside analog, interfering with the replication of the virus responsible for FIP. Accurate dosing and administration are paramount for its efficacy.

GS-441524 injection preparation

Purpose: 100ml GS 441524 injection liquid (15 mg/ml)

Material we need:

1500 mg GS441524

5 mL Ethanol

30 mL Propylene glycol 

45 mL PEG 400

20 mL Saline for injection (pH 1.5 with HCI)


  1. Mix 450 mL PEG 400 and 20 mL Saline.
  2. Dissolve 1500 mg GS441524 in the above solution with stir.
  3. Add 30 mL Propylene glycol and Saline for injection to 100 mL.
  4. Filter through 0.22 um sterile filter membrane.
  5. Divide into several vial if needed and store at 4 ℃.

Though Method seems simple, a lab sterile chamber may be a must to perform the it. If there is no such lab around, 15 mg/mL GS 441524 injection (5 mL) cost around 50-60 USD on Google or facebook.

GS-441524 pill preparation

Purpose: 100 pills GS 441524 tablet (10 mg per pill)

Material we need:

1000 mg GS441524

5g Starch

4.5g Microcrystalline cellulose


  1. Mix 1000 mg GS441524 with 5g Starch and 4.5g Microcrystalline cellulose.
  2. Fill the mixed powder into a tableting machine.
  3. Make the machine work and get the pill.
  4. Store in a cool and try place.

Though Not like injection require sterile environment, Tableting machine is not a common tool for most family. If there is no such tool around, 10mg pill may be found on Google and FB. Price is around 0.8-1.2 USD per mg. It means 10mg GS441524 pill is 8-12USD per pill; 25mg GS441524 pill is 20-30USD per pill; 50mg GS441524 pill is 40-60USD per pill.


The world of FIP treatment is filled with hope, challenges, and complex choices. The option to prepare GS-441524 at home is a testament to the unwavering commitment of cat owners to their feline companions. However, it should be approached with the utmost responsibility, ethics, and consideration for your cat’s well-being.

In your pursuit of alternative treatments, remember that informed decisions are your greatest asset. Prioritize open communication with your veterinarian, stay vigilant about safety and ethical standards, and keep the love and care for your cat at the heart of every choice you make.

Cracking the Code: Is FIP Warriors Legit?

Discover the truth about FIP Warriors: Is it a legit solution for Feline Infectious Peritonitis (FIP)? Uncover expert insights, real-life experiences, and the critical factors to consider when evaluating alternative treatments. Your cat’s well-being depends on informed decisions.

What is FIP Warriors

In recent years, one name has stirred both hope and skepticism among cat owners – “FIP Warriors”. FIP Warriors is a community of cat owners and advocates dedicated to raising awareness and providing support for cats diagnosed with Feline Infectious Peritonitis (FIP). In this article, we’ll delve into the world of FIP Warriors, addressing the burning question: Is FIP Warriors legit?

Is FIP Warriors Legit?

FIP Warriors revolves around the use of GS-441524, a drug that has shown potential in treating FIP. Up to now, FIP Warriors and its admins helped countless FIP cats and so many cats’ parents. It’s true that this community bought FIP parents hope to save their baby. However, given the GS 441524 patent is still unavailable for animal usage, any supplier of GS-441524 IS with a legitimate issue. So the answer is negative.

FIP Warriors claiming that other suppliers are scams and with low quality.

FIP Warriors is a reseller at high price

1. Someone post on one of their groups seeking FIP treatment.

2. Admins played a role of cat owners and enthusiastic helpers chime in, respond either publicly or privately using languages such as ‘I have pm’ed you’. Admin are assigned territories and have sales targets. Other Admins play the role of cat owners and responding to the posts to validate what the selling admin claims.

3. Cat’s owners are steered towards an ‘approved’ brand based on their budget and willingness to pay. If they can afford higher price products, Mutian is usually offered as the default choice. If they have limited funds, then a low price brand is offered. Either way, only the brands that have entered into commission paying agreements are promoted to cat owners. “

Advice to parents

Make GS 441524 formulation on your own

If you may find a lab or alike, it’s easy and affordable to make the injection and pill on your own. May Find how to make GS 441524 formulation here.

Find a reliable source with affordable price

Top 5 supplier is shared here.

GS-441524, GS441524, GS-441, GS441, Feline infectious peritonitis, FIP, treatment, tablet, capsule, injection

The nucleoside analog GS-441524 strongly inhibits feline infectious peritonitis (FIP) virus in tissue culture and experimental cat infection studies


Feline infectious peritonitis (FIP) is a common and highly lethal coronavirus disease of domestic cats. Recent studies of diseases caused by several RNA viruses in people and other species indicate that antiviral therapy may be effective against FIP in cats. The small molecule nucleoside analog GS-441524 is a molecular precursor to a pharmacologically active nucleoside triphosphate molecule. These analogs act as an alternative substrate and RNA-chain  terminator of viral RNA  dependent RNA polymerase. We determined that GS-441524 was non-toxic in feline cells at concentrations as high as 100 uM and effectively inhibited FIPV replication  in cultured CRFK cells and in naturally infected feline peritoneal macrophages at concentrations as low as 1 uM. We determined the pharmacokinetics of GS-441524 in cats in vivo and established a dosage that would sustain effective blood levels for 24 h. In an experimental FIPV infection of cats, GS-441524 treatment caused a rapid reversal of disease signs and return to normality with as little as two weeks of treatment in 10/10 cats and with no apparent toxicity.

The nucleoside analog GS-441524 strongly inhibits feline infectious peritonitis (FIP) virus in tissue culture and experimental cat infection studies – PubMed (


How Do Cats Get FIP: the Causes and Risk Factors

We often encounter concerned cat owners seeking answers about Feline Infectious Peritonitis (FIP). This complex disease can be devastating, and understanding how cats contract FIP is crucial to its prevention and management. In this comprehensive guide, we will delve into the causes, risk factors, clinical signs, diagnosis, and prevention of FIP, shedding light on this enigmatic feline disease.

What Is FIP?

Feline Infectious Peritonitis, or FIP, is a formidable adversary in the world of feline health. It is caused by a coronavirus called feline coronavirus (FCoV). Not all FCoV infections lead to FIP; in fact, most result in a benign, intestinal infection. However, in a small percentage of cases, FCoV can mutate into FIP, leading to severe illness.

Before we explore how cats contract FIP, let’s understand the role of feline coronavirus (FCoV). FCoV is relatively common among cats and is typically a benign, intestinal infection. Most cats that contract FCoV experience mild or no symptoms and eventually clear the virus from their system.

microscopic shot of a virus

Modes of Transmission

So, how do cats get FIP and is it contagious to other cats? The primary mode of transmission is through the fecal-oral route. Cats can become infected by coming into contact with the feces of an infected cat, either through shared litter boxes, grooming, or environmental contamination. FCoV can survive in the environment for extended periods, making it a persistent threat.

Additionally, direct cat-to-cat transmission is possible through behaviors such as biting or close contact. This is especially relevant in multi-cat households or environments with a high cat population density.

Can My Indoor Cat Get FIP?

Not all cats exposed to FCoV will develop FIP, and it’s natural to wonder, “Can my indoor cat get FIP?” While indoor cats have a reduced risk compared to outdoor cats, FIP can still affect them if they come into contact with the virus. Factors that increase the risk of FIP include:

Genetic Predisposition: Some cats may have genetic factors that make them more susceptible to FIP.

-Crowded Living Conditions: Overcrowding and high cat population density can increase the likelihood of FCoV transmission.

Stress: Stress weakens the immune system and can make a cat more susceptible to FIP.

-Weakened Immune System: Cats with compromised immune systems are at a higher risk.

Clinical Signs of FIP

Understanding how cats contract FIP is essential, but recognizing the clinical signs is equally important. FIP can manifest in two primary forms: effusive (wet) and non-effusive (dry). Common symptoms include:

– Fever

– Weight Loss

– Lethargy

– Distended Abdomen (in wet FIP)

– Neurological Signs (in some cases)

These symptoms can be subtle and easily mistaken for other illnesses, making FIP a challenging disease to diagnose definitively.

Diagnosing FIP can be complex and often requires multiple diagnostic tests. Veterinarians use blood tests, fluid analysis, and sometimes tissue biopsies to reach a diagnosis. However, even with these tools, FIP remains a challenging disease to confirm definitively.

If you suspect your cat has FIP, it’s crucial to consult with a veterinarian promptly. Early intervention can make a significant difference in managing the disease.

Preventing FIP and Its Spread to Other Cats

Preventing FIP and its spread to other cats centers around minimizing the risk of FCoV exposure and supporting your cat’s immune system. Here are some preventive measures:

Reducing Stress: Create a low-stress environment for your cat.

Maintaining Good Hygiene: Practice good hygiene, especially in multi-cat households.

Isolating Infected Cats: If one of your cats is diagnosed with FIP, isolate them to prevent transmission.

Vaccination (if applicable): Some vaccines may help reduce the risk of FIP and its spread to other cats, but their efficacy can vary.

At last

Understanding how cats contract FIP is a vital step in managing and preventing this challenging disease, especially if you have concerns about FIP being contagious to other cats. While FIP can be devastating, early detection and supportive care can improve a cat’s quality of life. Responsible pet ownership, regular veterinary check-ups, and prompt action if FIP is suspected are essential in the battle against this complex disease.

For further information on FIP and its prevention, consult your veterinarian and consider the following resources:

Remember, your dedication and vigilance as a cat owner play a pivotal role in keeping your feline friend healthy and happy while preventing the spread of FIP to other cats.

FIP Cats and GS-441524: A Ray of Hope in the Battle Against Feline Infectious Peritonitis

We’ve witnessed the heartache that Feline Infectious Peritonitis (FIP) can bring to cat owners. The diagnosis of this complex viral disease is often met with worry, confusion, and emotional turmoil. However, amidst the challenges, there’s a glimmer of hope in the form of GS-441524, an antiviral drug that has emerged as a beacon of possibility in the realm of FIP treatment.

Feline Infectious Peritonitis: A Complex Viral Disease

FIP is a formidable adversary. It can manifest in various forms, with symptoms ranging from fever and lethargy to weight loss and fluid accumulation in the abdomen or chest. Cat owners often find themselves navigating a maze of uncertainty when their beloved feline companions receive an FIP diagnosis.

The Role of GS-441524 in FIP Treatment


Amidst the adversity, GS-441524 shines as a potential game-changer in the fight against FIP. This antiviral drug holds the promise of combating the FIP virus and providing afflicted cats with a chance at a better life.

GS-441524 is an adenosine nucleotide analog antiviral, similar to remdesivir. This molecule was patented in 2009 by Gilead Sciences. In vitro studies of GS-441524 have determined it has a higher EC50 than remdesivir against a number of viruses, meaning GS-441524 is less potent. Remdesivir and GS-441524 were both found to be effective in vitro against feline coronavirus strains responsible for feline infectious peritonitis (FIP). Remdesivir was never tested in cats, but GS-441524 has been found to be effective treatment for FIP and is widely used despite no official FDA approval due to Gilead’s refusal to license this drug for veterinary use.

While GS-441524 isn’t a guaranteed cure, its use in treating FIP is backed by research and clinical trials. This gives cat owners a ray of hope and a potential path towards better health for their furry friends.

Anti Virus Mechanism of GS-441524

Intracellular triple-phosphorylation of GS-441524 yields its active 1′-cyano-substituted adenosine triphosphate analogue, which directly disrupts viral RNA replication by competing with endogenous NTPs for incorporation into nascent viral RNA transcripts and triggering delayed chain termination of RNA-dependent RNA polymerase.

Tolerance of GS-441524

In vitro experiments in Crandell Rees feline kidney (CRFK) cells found GS-441524 was nontoxic at 100 µM concentrations, 100 times the dose effective at inhibiting FIPV replication in cultured CRFK cells and infected macrophages. Clinical trials in cats indicate the drug is well-tolerated, with the primary side effect being dermal irritation from the acidity of the injection mix.

Some researchers suggesting its utility as a treatment for COVID-19 have pointed out advantages over remdesivir, including lack of on-target liver toxicity, longer half-life and exposure (AUC) and much cheaper and simpler synthesis.

Types of GS-441524 Formulations

GS-441524 is available in various formulations, each with its own set of advantages and considerations. These formulations include oral medications, injections, and other delivery methods.


Though GS-441524 is typically administered as an injectable solution, there are other formulations such as oral medications. GS-441524 oral form formulation is mostly available in tablet form. Tablet formulation strength varies from 5mg to 50 mg GS-441524 per pill. Cat owners may find the source on the FIP cat Facebook site or on Google. Just make sure the provider is reliable and the tablet strength is authentic.


GS-441524 was provided by Gilead Sciences as a pure and highly stable powder and diluted to a concentration of 10 or 15 mg/ml in:

  • 5% ethanol
  • 30% propylene glycol
  • 45% PEG 400 (polyethylene glycol)
  • 20% water with HCl to adjust the resulting pH to 1,5

The resulting mixture was shaken to dissolve in a sterile 50 ml flask and then placed in an ultrasonic bath for 5-20 minutes until it became completely clear. The drug thus dissolved was then stored in a refrigerator and used within 3-4 weeks.

The choice of formulation can impact the ease of administration and the effectiveness of treatment. For example, some cats may tolerate oral medications better, while others may benefit from injections. Discussing the options with your veterinarian is crucial in determining the most suitable form of GS-441524 for your cat.

Potential Benefits and Risks of GS-441524 Treatment

The potential benefits of GS-441524 treatment are encouraging. Cats undergoing treatment may experience improved quality of life, including reduced symptoms and enhanced vitality. Success stories of cats achieving remission offer hope to cat owners facing the daunting prospect of FIP.

However, it’s essential to be aware of potential risks and side effects associated with GS-441524. Not all cats may respond the same way to the medication, and some may experience injection site reactions or other adverse effects. Close monitoring and open communication with your veterinarian are vital in addressing any concerns or challenges that may arise during treatment.

Cost Considerations

Managing the cost of FIP treatment with GS-441524 is a concern for many cat owners. The price of the medication can vary, and it’s essential to explore potential sources for obtaining it. Some cat owners have found success in purchasing from trusted online sources, while others may seek assistance from organizations that provide financial aid for veterinary treatments. This tool may help a little bit to estimate the GS-441524 treatment cost based on cats’s weight and FIP type

Balancing the financial aspect of treatment with the desire to provide the best care for your cat requires careful consideration and planning.

Real Stories: Successes and Challenges

To shed light on the real-world experiences of cat owners facing FIP, let’s delve into some stories of hope and resilience. These anecdotes highlight not only the successes but also the challenges that cat owners may encounter during treatment.

Jane’s Story:* Jane’s cat, Whiskers, was diagnosed with the wet form of FIP. After discussing treatment options with her veterinarian, Jane decided to pursue GS-441524 injections. The journey wasn’t without its difficulties, including initial injection site reactions and the stress of administering daily injections. However, with unwavering dedication and support from her veterinarian, Jane saw gradual improvements in Whiskers’ health. Over time, the fluid accumulation in Whiskers’ abdomen decreased, and he regained his playful spirit. Jane’s story showcases the importance of persistence and the positive outcomes that can result from GS-441524 treatment.

Mark’s Challenge:* Mark’s cat, Luna, was diagnosed with the dry form of FIP. Luna was a particularly challenging patient, often resisting medication and displaying signs of anxiety during the injection process. Mark’s veterinarian recommended adjusting the treatment plan to include a compounded liquid formulation of GS-441524, which Luna found more palatable. While the journey was still filled with ups and downs, Mark’s determination and his veterinarian’s guidance eventually led to a noticeable improvement in Luna’s condition. Mark’s experience highlights the importance of flexibility and finding the right treatment approach for each cat’s unique needs.

Last: Hope and Support for FIP Cats

In the face of FIP, cat owners are not alone. GS-441524 represents a ray of hope, offering the potential for improved quality of life and even remission for cats afflicted by this challenging disease. While the journey may be marked by challenges, uncertainties, and financial considerations, the unwavering commitment of cat owners, combined with the guidance of veterinary professionals, can pave the way for better health and happiness for their beloved feline companions.

Remember, you are your cat’s advocate and source of support. Your dedication and love play a pivotal role in your cat’s transformative journey toward health and happiness.

Thirty-two cats with effusive or non-effusive feline infectious peritonitis treated with a combination of remdesivir and GS-441524


GS-441524 has been successfully used to treat feline infectious peritonitis (FIP) in cats. However, the use of its prodrug, remdesivir, in combination with a PO GS-441524 containing product for the treatment of FIP has not yet been described.


Describe treatment protocols, response to treatment and outcomes in cats with FIP treated with a combination of PO GS-441524 and injectable remdesivir.


Thirty-two client-owned cats diagnosed with effusive or non-effusive FIP including those with ocular and neurological involvement.


Cats diagnosed with FIP at a single university hospital between August 2021 and July 2022 were included. Variables were recorded from time of diagnosis, and subsequent follow-up information was obtained from the records of referring veterinarians. All surviving cats were observed for the entire 12-week treatment period.


Cats received treatment with different combinations of IV remdesivir, SC remdesivir, and PO GS-441524 at a median (range) dosage of 15 (10-20) mg/kg. Clinical response to treatment was observed in 28 of 32 cats (87.5%) in a median (range) of 2 (1-5) days. Twenty-six of 32 cats (81.3%) were alive and in clinical and biochemical remission at the end of the 12-week treatment period. Six of 32 cats (18.8%) died or were euthanized during treatment with 4 of the 6 cats (66%) dying within 3 days of starting treatment.


We describe the effective use of injectable remdesivir and PO GS-441524 for the treatment of FIP in cats. Success occurred using different treatment protocols and with different presentations of FIP including cats with ocular and neurological involvement.


coronavirus, feline, FIP, microbiology, neurology, viral


GS-441524, GS441524, GS-441, GS441, Feline infectious peritonitis, FIP, treatment, tablet, capsule, injection

Antiviral treatment using the adenosine nucleoside analogue GS-441524 in cats with clinically diagnosed neurological feline infectious peritonitis


Feline infectious peritonitis (FIP) is caused by a mutant biotype of the feline enteric coro- navirus. The resulting FIP virus (FIPV) commonly causes central nervous system (CNS) and ocular pathology in cases of noneffusive disease. Over 95% of cats with FIP will suc- cumb to disease in days to months after diagnosis despite a variety of historically used treatments. Recently developed antiviral drugs have shown promise in treatment of non- neurological FIP, but data from neurological FIP cases are limited. Four cases of naturally occurring FIP with CNS involvement were treated with the antiviral nucleoside analogue GS-441524 (5-10 mg/kg) for at least 12 weeks. Cats were monitored serially with physi- cal, neurologic, and ophthalmic examinations. One cat had serial magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) analysis (including feline coronavirus [FCoV]) titers and FCoV reverse transcriptase [RT]-PCR) and serial ocular imaging using Fourier- domain optical coherence tomography (FD-OCT) and in vivo confocal microscopy (IVCM). All cats had a positive response to treatment. Three cats are alive off treatment (528, 516, and 354 days after treatment initiation) with normal physical and neurologic examinations. One cat was euthanized 216 days after treatment initiation following relapses after primary and secondary treatment. In 1 case, resolution of disease was defined based on normalization of MRI and CSF findings and resolution of cranial and caudal segment disease with ocular imaging. Treatment with GS-441524 shows clinical efficacy and may result in clearance and long-term resolution of neurological FIP. Dosages required for CNS disease may be higher than those used for nonneurological FIP.


antiviral, cat, corona virus, ophthalmology


GS-441524, GS441524, GS-441, GS441, Feline infectious peritonitis, FIP, treatment, tablet, capsule, injection

Efficacy and safety of the nucleoside analog GS-441524 for treatment of cats with naturally occurring feline infectious peritonitis


The aim of this study was to determine the safety and efficacy of the nucleoside analog GS-441524 for cats suffering from various forms of naturally acquired feline infectious peritonitis (FIP).


Cats ranged from 3.4–73 months of age (mean 13.6 months); 26 had effusive or dry-to-effusive FIP and five had non-effusive disease. Cats with severe neurological and ocular FIP were not recruited. The group was started on GS-441524 at a dosage of 2.0 mg/kg SC q24h for at least 12 weeks and increased when indicated to 4.0 mg/kg SC q24h.


Four of the 31 cats that presented with severe disease died or were euthanized within 2–5 days and a fifth cat after 26 days. The 26 remaining cats completed the planned 12 weeks or more of treatment. Eighteen of these 26 cats remain healthy at the time of publication (OnlineFirst, February 2019) after one round of treatment, while eight others suffered disease relapses within 3–84 days. Six of the relapses were non-neurological and two neurological. Three of the eight relapsing cats were treated again at the same dosage, while five cats had the dosage increased from 2.0 to 4.0 mg/kg q24h. The five cats treated a second time at the higher dosage, including one with neurological disease, responded well and also remain healthy at the time of publication. However, one of
the three cats re-treated at the original lower dosage relapsed with neurological disease and was euthanized, while the two remaining cats responded favorably but relapsed a second time. These two cats were successfully treated a third time at the higher dosage, producing 25 long-time survivors. One of the 25 successfully treated cats was subsequently euthanized due to presumably unrelated heart disease, while 24 remain healthy.

Conclusions and relevance

GS-441524 was shown to be a safe and effective treatment for FIP. The optimum dosage was found to be 4.0 mg/kg SC q24h for at least 12 weeks.


Nucleoside analog; GS-441524; feline infectious peritonitis; FIP; field trial


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